HYDRAULIC TRIM DEVICES, BOAT DRIVES INCORPORATING HYDRAULIC TRIM DEVICES, AND BOATS INCORPORATING THE SAME

Abstract

A hydraulic trim device is provided for a boat motor. The trim device includes a trimming cylinder, a piston rod received in a receptacle of the trimming cylinder and shaped to be movable within the trimming cylinder with respect to a central axis between first and second end positions. The piston rod includes a distal contact portion. A trimming plate of the trim device includes a base surface opposite an asymmetric contact surface that faces the piston rod, first and second side surfaces extending orthogonally from the base surface to first and second base points on the asymmetric contact surface. The asymmetric contact surface abuts the distal contact portion of the piston rod. Movement of the distal contact portion along the asymmetrical contact surface during a movement of the piston rod between the first and second end positions causes movement of the hydraulic trim device.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent application Ser. No. 18/052,250, entitled “HYDRAULIC TRIM DEVICE, BOAT DRIVE AND BOAT” and filed Nov. 3, 2022, which claims priority to German patent application 10 2021 213 912.4, filed Dec. 7, 2021, each of which is hereby incorporated by reference in its respective entirety.

FIELD

The present disclosure relates to motors for aquatic use such as boat motors, and more specifically, to hydraulic trim devices for boat motors.

BACKGROUND

Hydraulic trim devices are used in combination with a hydraulic lift device in an aquatic setting, such as, for example, in boat motors to pivot the boat motor (particularly an outboard motor). Conventional trim devices are subject to noise during operation of the boat motor. This is alleviated via the use of lubricants, which can be undesirable for ecological reasons, as such lubricants are subject to discharge into waterways when the boat is used.

SUMMARY

In one embodiment, a hydraulic trim device for a boat motor includes a trimming cylinder having an elongate body defining a receptacle that is elongated in an axial direction along a central axis of the elongate body, a piston rod received in the receptacle of the elongate body, the piston rod shaped to be movable within the trimming cylinder with respect to the central axis between a first end position and a second end position, the piston rod having a distal contact portion that extends axially with respect to the elongate body, and a trimming plate including a base surface opposite an asymmetric contact surface that faces the piston rod, a first side surface extending orthogonally from the base surface to a first base point on the asymmetric contact surface, and a second side surface extending orthogonally from the base surface to a second base point on the asymmetric contact surface. The trimming plate is positioned such that the asymmetric contact surface abuts the distal contact portion of the piston rod. Movement of the distal contact portion of the piston rod along the asymmetrical contact surface of the trimming plate during a movement of the piston rod between the first end position and the second end position causes movement of the hydraulic trim device.

In another embodiment, hydraulic trim device for a boat motor includes a trimming cylinder having an elongate body defining a receptacle that is elongated in an axial direction along a central axis of the elongate body, a piston rod received in the receptacle of the elongate body, the piston rod shaped to be laterally movable within the trimming cylinder with respect to the central axis between a first end position and a second end position, the piston rod having a distal contact portion that extends axially with respect to the elongate body to an extended position out of the receptacle, and a trimming plate including a base surface opposite an asymmetric contact surface that faces the piston rod, a first side surface extending orthogonally from the base surface to a first base point on the asymmetric contact surface, and a second side surface extending orthogonally from the base surface to a second base point on the asymmetric contact surface. The trimming plate is positioned such that the asymmetric contact surface abuts the distal contact portion of the piston rod. The first base point and the second base point are located on opposite ends of the asymmetrical contact surface. A first vertical distance between the first base point and the base surface is smaller than a second vertical distance between the second base point and the base surface.

In yet another embodiment, a boat motor includes a boat drive and a hydraulic trim device disposed on the boat drive. The hydraulic trim device includes a trimming cylinder having an elongate body defining a receptacle that is elongated in an axial direction along a central axis of the elongate body, a piston rod received in the receptacle of the elongate body, the piston rod shaped to be movable within the trimming cylinder with respect to the central axis between a first end position and a second end position, the piston rod having a distal contact portion that extends axially with respect to the elongate body, and a trimming plate including a base surface opposite an asymmetric contact surface that faces the piston rod, a first side surface extending orthogonally from the base surface to a first base point on the asymmetric contact surface, and a second side surface extending orthogonally from the base surface to a second base point on the asymmetric contact surface. The trimming plate is positioned such that the asymmetric contact surface abuts the distal contact portion of the piston rod. Movement of the distal contact portion of the piston rod along the asymmetrical contact surface of the trimming plate during a movement of the piston rod between the first end position and the second end position causes movement of the hydraulic trim device.

In another embodiment, a boat includes a hull and a boat motor. The boat motor includes a boat drive and a hydraulic trim device disposed on the boat drive. The hydraulic trim device includes a trimming cylinder having an elongate body defining a receptacle that is elongated in an axial direction along a central axis of the elongate body, a piston rod received in the receptacle of the elongate body, the piston rod shaped to be movable within the trimming cylinder with respect to the central axis between a first end position and a second end position, the piston rod having a distal contact portion that extends axially with respect to the elongate body, and a trimming plate including a base surface opposite an asymmetric contact surface that faces the piston rod, a first side surface extending orthogonally from the base surface to a first base point on the asymmetric contact surface, and a second side surface extending orthogonally from the base surface to a second base point on the asymmetric contact surface. The trimming plate is positioned such that the asymmetric contact surface abuts the distal contact portion of the piston rod. Movement of the distal contact portion of the piston rod along the asymmetrical contact surface of the trimming plate during a movement of the piston rod between the first end position and the second end position causes movement of the hydraulic trim device. The boat drive is pivotably arranged on the hull by the hydraulic trim device.

These and additional features provided by the embodiments described herein will be more fully understood in view of the following detailed description, in conjunction with the drawings.

BRIEF DESCRIPTION

The embodiments set forth in the drawings are illustrative and exemplary in nature and not intended to limit the subject matter defined by the claims. The following detailed description of the illustrative embodiments can be understood when read in conjunction with the following drawings, where like structure is indicated with like reference numerals and in which:

FIG. 1 is a first side view of a boat with an outboard motor;

FIG. 2 is a second side view of the boat shown in FIG. 1;

FIG. 3 is a side view of a hydraulic trim device according to a first embodiment with a trimming cylinder and a piston rod located in a first end position;

FIG. 4 is a side view of the hydraulic trim device shown in FIG. 3 with the piston rod in an intermediate position;

FIG. 5 is a side view of the hydraulic trim device shown in FIG. 3 with the piston rod in a second end position;

FIG. 6 is a detail view of the hydraulic trim device shown in FIG. 3;

FIG. 7 is a side view of a hydraulic trim device according to a second embodiment;

FIG. 8 is a simplified side view of a hydraulic trim device in a first arrangement showing the piston rod in a first position according to a third embodiment;

FIG. 9 is a simplified side view of the hydraulic trim device shown in FIG. 8 in a second arrangement showing the piston rod in a second position; and

FIG. 10 is a simplified side view of the hydraulic trim device shown in FIGS. 8 and 9 in a third arrangement showing the piston rod in a third position.

DETAILED DESCRIPTION

The present disclosure relates generally to hydraulic trim devices in boat motors. As will be described in further detail herein, such hydraulic trim devices include trimming cylinders that are particularly designed with a movable piston rod received in an elongate body of the trimming cylinder. The movable piston rod is generally shaped so that it can be moved within the trimming cylinder with respect to a central axis between end positions. In addition, the movable piston rod has a distal contact portion that abuts a trimming plate of the hydraulic trim device. The trimming plate is asymmetrically shaped such that when the movable piston rod moves with respect to the end positions, the asymmetric shape of the trimming plate guides the distal contact portion of the movable piston rod in a particular movement.

Hydraulic trim devices for boat motors include, for example, those disclosed in U.S. Pat. No. 5,597,333 or International Patent Application No. WO 01/098142. Typically, these hydraulic trim devices are used in combination with a hydraulic lift device. These combined devices are used on the one hand to pivot the boat drive, for example an outboard motor, via at least one lift cylinder of the lift device into a rest position in which the propeller of the drive is almost completely or fully lifted out of the water.

Further, at least one trimming cylinder of the trim device is used to perform a so-called power trim while the boat is travelling. Here, the boat drive is finely adjusted by rotation around the transverse axis of the boat in order to obtain an optimum alignment or position of the hull of the boat with respect to the water surface during travel. A suboptimal alignment between the hull and the water surface results in a loss of propulsion due to cavitation of the propeller as well as incorrect power input direction, unsteady handling and increased fuel consumption.

For this purpose, the hydraulic trim device has, in addition to the at least one trimming cylinder, a hydraulic unit and a trimming plate. The trimming cylinder includes a piston rod axially movable in the trimming cylinder between a first end position and a second end position. In sense of the present disclosure, the first end position may correspond to a minimum trim position, which position may also correspond to the fully retracted position of the piston rod. The second end position may correspond to a maximum trim position, whereby this may correspond to a fully extended position of the piston rod. To extend the piston rod in the direction of the second end position, the trimming cylinder is pressurized in a known manner via the hydraulic unit.

The piston rod has a contact portion which is in contact with a contact surface of the trimming plate. The trimming plate is disposed on the boat drive so that the boat drive is pivoted relative to the hull by extending and retracting the piston rod. When the piston rod moves between the first end position and the second end position, the contact portion moves relative to the contact surface along the contact surface.

In known trim devices, the movement between the contact portion and the contact surface can result in transverse forces that increase wear, for example on guide bushings of the trimming cylinder. In particular, the friction between the contact portion and the contact surface also causes the piston rod to stop and move alternately, which is also noticeable in the form of vibrations. This phenomenon is also referred to as the slip-stick effect. As a result, there is also an undesirable noise formation, which manifests itself as a kind of rattling. As a general remedy, it is suggested that the contact surface or contact portion be lubricated regularly, which also has a positive effect on the wear between the contact surface and contact portion.

In addition, U.S. Pat. No. 5,597,333 suggests that the trimming plate may be in the nature of a ball bearing, or that the contact surface may be symmetrically concavely curved, e.g., curved inward away from the contact portion.

The disadvantage of this is that the solution in the form of a ball bearing is very complex and therefore expensive to manufacture. The solution with concavely curved contact surfaces also only works satisfactorily with regular application of lubricant, whereby the transverse forces are even higher, depending on the position of the piston rod, than with a completely flat contact surface. Increased use of lubricant is also undesirable for ecological reasons, as a considerable proportion of the lubricant is discharged into the waterways due to its aquatic use in boat motors.

It is therefore the object of the present disclosure to provide a hydraulic trim device for a boat motor, with which the undesirable transverse forces as well as the undesirable noise development can be effectively prevented with reduced use of lubricant. The solution of the problem is achieved with a hydraulic trim device as disclosed herein.

The hydraulic trim device according to the present disclosure is characterized over conventional trim devices in that the contact surface at least partially has a convex curvature in the direction of the piston rod. In other words, the contact surface at least partially curved outwardly in the direction of the piston rod or the contact portion. In this way, it can be ensured that the transverse force is significantly minimized, whereby the use of lubricant can also be noticeably reduced. Tests by the applicant have shown that, compared with conventional trim devices with flat contact surfaces, up to five times the number of movements can be achieved with the same use of lubricant.

In some aspects, the contact portion is in a first contact position in the first end position of the piston rod and in a second contact position in the second end position of the piston rod. In some aspects, the convex curvature of the contact surface between the first contact position and the second contact position is asymmetrical. In other words, the trimming plate is thus symmetrical along a first imaginary plane between the first end position and the second end position, but asymmetrical along a second plane perpendicular to the first plane. Thus, the trimming plate can be individually matched to the corresponding kinematics of the boat drive with respect to trim or power trim.

In some aspects, the contact surface between the first contact position and the second contact position has a completely convex curvature in the direction of the piston rod. This means that the contact surface is not only convexly curved partially or in sections, but completely.

In some aspects, the piston rod has a central mid-axis, the convex curvature of the contact surface being such that the central mid-axis of the piston rod in any position of the piston rod between the first end position and the second end position is orthogonal with respect to the trimming plate or contact surface or is inclined by at most 6° on the trimming plate or contact surface. If the central mid-axis of the piston rod is inclined on the trimming plate or the contact surface, it is useful if the central mid-axis is inclined between 1.5° and 4.5°, by 2° to 4°, or by 3° on the trimming plate or the contact surface. A completely orthogonal arrangement results in the lowest transverse forces and consequently the lowest wear. With a certain inclination, the slip-stick effect can be largely suppressed, with tests by the applicant showing that the best compromise between reduced transverse forces and reduced slip-stick effect can be achieved at an inclination of 3°.

In some aspects, the central mid-axis is inclined in the direction of the first contact position. By inclining the central mid-axis in the direction of the first contact position, the slip-stick effect is noticeably reduced, especially when the piston rod is extended.

In some aspects, the contact portion is a spherical contact portion (which may also be referred to as a convex contact portion). This results in point contact between the contact portion and the contact surface. Alternatively, the contact portion can be a planar contact portion. This results in a line contact, which reduces the surface pressure. Furthermore, a flat contact portion is easy to manufacture. Of course, other shapes of the contact portion are also conceivable, for example semi-cylindrical, partially cylindrical or frustoconical.

Furthermore, the solution of the problem is achieved with a boat motor disclosed herein. According to the present disclosure, the boat motor comprises a trim device described above as well as a boat drive. The trimming plate is attached to the boat drive. The boat drive may in particular be an outboard motor or a stern drive.

Furthermore, the solution of the task succeeds with a boat, in particular a sports boat. The boat according to the present disclosure has a hull and a boat motor described above, the boat drive being pivotably arranged on the hull by means of the hydraulic trim device.

In FIGS. 1 and 2, a boat 101 with a boat motor 100 according to the present disclosure is shown. In this embodiment, the boat is a recreational boat and the boat motor 100 has a boat drive in the form of an outboard motor 105. The outboard motor 105 includes a propeller 104 and is pivotable on a hull 102 of the boat 101 via a joint 103 between a lowered position (see FIG. 1) and a raised position (see FIG. 2). For this purpose, the boat 101 has a hydraulic trim device 1 according to the present disclosure as part of a combined hydraulic trim-lift device 110.

The hydraulic trim lift device 110 has a lift cylinder 106 and, in this embodiment, a trimming cylinder 2 as part of the hydraulic trim device 1. Of course, embodiments with two or more lift cylinders and with two or more trimming cylinders are also conceivable. Furthermore, a hydraulic unit (not shown in more detail) is provided, via which the lift cylinder 106 and the trimming cylinder 2 can be pressurized in a known manner.

With reference also to FIGS. 3 and 5, the trimming cylinder 2 has a piston rod 3 which is movable in a first axis (e.g., in the +/−X directions of the coordinate axes of FIGS. 1, 3, and 5) between a first end position EP1 (depicted in FIG. 3) and a second end position EP2 (depicted in FIG. 5) in the trimming cylinder 2. By pressurizing the trimming cylinder 2 via the hydraulic unit, the piston rod 3 is extended in the conventional manner (e.g., in the +Y direction of the coordinate axes of FIG. 1). A contact portion 4, 4′ is provided at the axial end of the piston rod 3 facing a trimming plate 5 being disposed on the outboard motor 105. The contact portion 4, 4′ is in contact with a contact surface 6 of the trimming plate 5.

During power trimming while the boat 101 is travelling, the trimming cylinder 2 extends and the contact portion 4, 4′ of the piston rod 3 of the trimming cylinder 2 moves along the contact surface 6 of the trimming plate 5 to pivot the outboard motor 105 relative to the hull 102 along the joint 103 about the transverse axis of the boat 101 to fine-tune between the lowered position (FIG. 1) and raised position (FIG. 2). Suboptimal alignment between the hull 102 and the water surface results in a loss of propulsion due to cavitation of the propeller 104 as well as incorrect force application direction, erratic handling and increased fuel consumption.

In FIG. 3, a hydraulic trim device 1 is shown as part of a combined hydraulic trim-lift device 110 according to a first embodiment. The outboard motor 105 is not shown for clarity reasons. The state shown in FIG. 3 corresponds essentially to the state shown in FIG. 1 with the outboard motor 105 fully lowered and therefore not finely adjusted. The piston rod 3 of the trimming cylinder 2 is in the first end position EP1 (e.g., toward the −X direction of the coordinate axes of FIG. 3 relative to a central axis of the trimming cylinder 2) and the contact portion 4 of the piston rod 3 is in a first contact position AP1 on the contact surface 6 of the trimming plate 5.

In this embodiment, the contact portion 4 of the piston rod 3 is spherical (e.g., a convex contact portion in the direction of the trimming plate 5), so that there is point contact between the contact portion 4 and the contact surface 6. As shown, the contact surface 6 of the trimming plate 5 has a convex curvature in the direction of the piston rod 3 or the contact portion 4, as will be described in more detail below.

To perform a power trim, the trimming cylinder 2 is pressurized by the hydraulic unit in the conventional manner and the piston rod 3 extends in the +Y direction of the coordinate axes of FIG. 3. Here, the contact portion 4 of the piston rod 3 moves along the contact surface 6 of the trimming plate 5 and a force is applied to the outboard motor 105 via the trimming plate 5 so that the outboard motor 105 is moved or pivoted relative to the hull 102 via the joint 103.

FIG. 4 shows an intermediate position of the contact portion 4 of the piston rod 3 on the contact surface 6 of the trimming plate 5, and FIG. 5 shows a state essentially corresponding to the state shown in FIG. 2, which corresponds to maximum power trim. In the state shown in FIG. 5, the piston rod 3 is in the second end position EP2 (e.g., towards the +X direction of the coordinate axes relative to a central axis of the trimming cylinder 2) and the contact portion 4 of the piston rod 3 is in a second contact position AP2 on the contact surface 6 of the trimming plate 5.

FIG. 6 shows a detail from FIG. 3, in which the contact portion 4 of the piston rod 3 is located in the first contact position AP1 on the contact surface 6 of the trimming plate 5. The piston rod 3 has a central mid-axis MA. The curvature of the contact surface 6 of the trimming plate 5 is selected such that the central mid-axis MA is always inclined by a predetermined angle α relative to the force introduction direction KE shown as a dashed arrow during movement along the contact surface 6 between the first contact position AP1 and the second contact position AP2. In this exemplary embodiment, α=3°. In other words, the piston rod 3 is not orthogonal on the contact surface 6 of the trimming plate 5, but the central mid-axis MA is inclined in the direction of the first contact position AP by the angle α=3° with respect to the force introduction direction KE. The contact surface 6 or the curvature of the contact surface 6 respectively is configured so that the angle α remains the same for all positions of the contact portion 4 relative to the contact surface 7.

If the central mid-axis MA of the piston rod 3 were completely orthogonal relative to the trimming plate 5 or contact surface 6, α=0° and MA=KE would apply. In this case, the lateral forces would be minimal due to the orthogonal force application, but a noticeable slip-stick effect could occur. It has been shown that with α≤6° and especially in the range of 1.5°≤α≤4.5° an optimum compromise between introduced transverse forces and occurrence of the slip-stick effect can be achieved.

When configuring the curvature of the contact surface 6 of the trimming plate 5, this is initially selected so that it is individually matched to the corresponding kinematics of the boat motor 100 with regard to trim or power trim. Here, it is notionally assumed that an orthogonal alignment of the central mid-axis MA of the piston rod 3 to the trimming plate 5 or contact surface 6 is always to be achieved. Subsequently, if required, the contact surface 6 of the trimming plate 5 is rotated by an angle α, the angle α being at most 6° (e.g., less than or equal to 6°). This results in an asymmetrical and convex curvature of the contact surface 6 of the trimming plate 5 between the first contact position AP1 and the second contact position AP2.

In FIG. 7, a hydraulic trim device 1 is shown as part of a combined hydraulic trim-lift device 110 according to a second embodiment. The second embodiment of the hydraulic trim device 1 differs from the first embodiment shown in FIGS. 3 to 6 only in the design of the contact portion 4′ of the piston rod 3.

As shown, the contact portion 4′ of the piston rod 3 in this second embodiment is designed as a flat surface (e.g., a planar contact portion). Thus, in contrast to the spherical (e.g., convex) design of the contact portion according to the first embodiment, there is a line of contact between the contact portion 4′ of the piston rod 3 and the contact surface 6 of the trimming plate 5. In this embodiment, the angle α=0°. Overall, this results in lower surface pressure with minimized slip-stick effect.

FIGS. 8 to 10 depict a simplified hydraulic trim device 1 with the piston rod 3 shown in different positions along the contact surface 6. As depicted in FIGS. 8-10 and described in greater detail hereinbelow, the contact surface 6 of the trimming plate 5 has a varying slope when traversing from a first end of the contact surface 6 to a second end of the contact surface 6. In some embodiments, the slope of the contact surface 6 of the trimming plate 5 may increase or decrease when the trimming plate 5 is traversed from the first end to the second end thereof. In some embodiments, the slope of the contact surface 6 of the trimming plate 5 may increase or decrease monotonically (e.g., at a consistent rate) when traversing the contact surface 6 from the first end to the second end thereof.

The contact portion 4′ of the piston rod 3 in this third embodiment is designed as a flat surface e.g., the contact portion 4′ is a planar contact portion. The contact portion 4′ is connected to a base portion 18 of the piston rod 3 by a transition portion 17. The transition portion 17 concavely tapers between the base portion 18 and the contact portion 4′. Thus, in contrast to the spherical design of the contact portion according to the first embodiment, there is a line contact between the contact portion 4′ of the piston rod 3 and the contact surface 6 of the trimming plate 5. In this embodiment, the angle α=0°. Overall, this results in lower surface pressure with minimized slip-stick effect.

The trimming plate 5 comprises a base surface 7 defining a base plane 8 (e.g., extending in the plane defined by the +X/−X and +Z/−Z directions of the coordinate axes of FIGS. 8-10). That is, the base surface 7 is generally planar and extending in the base plane 8. The trimming plate 5 further comprises a first base point 9 and a second base point 10. The first base point 9 defines a first end of the contact surface 6 (e.g., the furthest point of the contact surface 6 in the −X direction of the coordinate axes of FIGS. 8-10). The second base point 10 defines a second end of the contact surface 6 (e.g., the furthest point of the contact surface 6 in the +X direction of the coordinate axes of FIGS. 8-10). Hence, the contact surface 6 is defined and limited by the first base point 9 and the second base point 10. In some embodiments, the contact surface 6 has a slope that may monotonically increase from the first base point 9 to the second base point 10. As used herein, the term “monotonically increase” relates to a change in slope that consistently increases (e.g., within a margin of error of +/−5%) over a full span of the contact surface 6 between the first base point 9 and the second base point 10.

The trimming plate 5 is also defined by a first vertical distance 11 between the first base point 9 and the base surface 7 and a second vertical distance 12 between the second base point 10 and the base surface 7. In some embodiments, the first vertical distance 11 is measured as a straight line extending from the first base point 9 in a direction orthogonal to the base plane 8. Similarly, the second vertical distance 12 is measured as a straight line extending from the second base point 10 in a direction orthogonal to the base plane 8. Due to the change in slope of the contact surface 6 and due to the base surface 7 being planar as noted hereinabove, the first vertical distance 11 is smaller than the second vertical distance 12. Hence, the maximum distance between the base surface 7 and any point of the contact surface 6 cannot be provided between the first base point 9 and the second base point 10, but rather coincides with the second base point 10. As a result, the contact surface 6 has a shape different from a conventional disk segment (e.g., a region of a disk which is “cut off” from the rest of the disk by a straight line, which may also be referred to as a circular segment). That is, while a conventional disk segment would be characterized as having a maximum distance between the straight line (which corresponds to the base plane) and any point of the contact surface exactly in the middle. Thus, a contact surface provided as a disk segment has a symmetrical shape, whereas the contact surface 6 according to the present disclosure has an asymmetrical shape.

In the embodiment shown in FIGS. 8 to 10, the trimming plate 5 comprises a first side surface 13 and a second side surface 14. The first side surface 13 orthogonally extends from the base surface 7 to the first base point 9 relative to the base surface 7 (e.g., generally in the +X/−X directions of the coordinate axes of FIGS. 8-10). The first base point 9 thus defines an intersection of the first side surface 13 and the contact surface 6. The second side surface 14 orthogonally extends from the base surface 7 to the second base point 10 relative to the base surface 7 (e.g., generally in the +X/−X directions of the coordinate axes of FIGS. 8-10). The second base point 10 thus defines an intersection of the second side surface 14 and the contact surface 6. The first side surface 13 has a first length 15 and the second side surface 14 has a second length 16. Due to the asymmetrical shape of the contact surface 6 as noted herein, the first length 15 is smaller than the second length 16.

Claims

1. A hydraulic trim device for a boat motor, the hydraulic trim device comprising:

a trimming cylinder having an elongate body defining a receptacle that is elongated in an axial direction along a central axis of the elongate body;

a piston rod received in the receptacle of the elongate body, the piston rod shaped to be movable within the trimming cylinder with respect to the central axis between a first end position and a second end position, the piston rod having a distal contact portion that extends axially with respect to the elongate body; and

a trimming plate including a base surface opposite an asymmetric contact surface that faces the piston rod, a first side surface extending orthogonally from the base surface to a first base point on the asymmetric contact surface, and a second side surface extending orthogonally from the base surface to a second base point on the asymmetric contact surface, the trimming plate positioned such that the asymmetric contact surface abuts the distal contact portion of the piston rod, wherein movement of the distal contact portion of the piston rod along the asymmetrical contact surface of the trimming plate during a movement of the piston rod between the first end position and the second end position causes movement of the hydraulic trim device.

2. The hydraulic trim device according to claim 1, wherein a slope of the asymmetrical contact surface monotonically increases between the first base point and the second base point.

3. The hydraulic trim device according to claim 1, wherein the first side surface has a first vertical distance and the second side surface has a second vertical distance, and the first vertical distance is smaller than the second vertical distance.

4. The hydraulic trim device according to claim 1, wherein the distal contact portion of the piston rod is a planar contact portion.

5. The hydraulic trim device according to claim 1, wherein the distal contact portion of the piston rod is a convex contact portion.

6. The hydraulic trim device according to claim 5, wherein the piston rod defines a central mid-axis, and wherein the convex contact portion is such that the central mid-axis of the piston rod in any position of the piston rod between the first end position and the second end position is orthogonal with respect to the trimming plate.

7. The hydraulic trim device according to claim 5, wherein the piston rod defines a central mid-axis, and wherein the convex contact portion is such that the central mid-axis of the piston rod in any position of the piston rod between the first end position and the second end position is inclined at an angle with respect to the trimming plate, wherein the angle is less than or equal to 6°.

8. The hydraulic trim device according to claim 7, wherein the angle is in a range from 1.5° to 4.5° or from 2° to 4°.

9. The hydraulic trim device according to claim 7, wherein the angle is 3°.

10. A hydraulic trim device for a boat motor, the hydraulic trim device comprising:

a trimming cylinder having an elongate body defining a receptacle that is elongated in an axial direction along a central axis of the elongate body;

a piston rod received in the receptacle of the elongate body, the piston rod shaped to be laterally movable within the trimming cylinder with respect to the central axis between a first end position and a second end position, the piston rod having a distal contact portion that extends axially with respect to the elongate body to an extended position out of the receptacle; and

a trimming plate including a base surface opposite an asymmetric contact surface that faces the piston rod, a first side surface extending orthogonally from the base surface to a first base point on the asymmetric contact surface, and a second side surface extending orthogonally from the base surface to a second base point on the asymmetric contact surface, the trimming plate positioned such that the asymmetric contact surface abuts the distal contact portion of the piston rod, wherein: the first base point and the second base point are located on opposite ends of the asymmetrical contact surface, and a first vertical distance between the first base point and the base surface is smaller than a second vertical distance between the second base point and the base surface.

11. The hydraulic trim device according to claim 10, wherein a slope of the asymmetrical contact surface monotonically increases between the first base point and the second base point.

12. The hydraulic trim device according to claim 10, wherein the distal contact portion of the piston rod is a planar contact portion.

13. The hydraulic trim device according to claim 10, wherein the distal contact portion of the piston rod is a convex contact portion.

14. The hydraulic trim device according to claim 13, wherein the piston rod defines a central mid-axis, and wherein the convex contact portion is such that the central mid-axis of the piston rod in any position of the piston rod between the first end position and the second end position is orthogonal with respect to the trimming plate.

15. The hydraulic trim device according to claim 13, wherein the piston rod defines a central mid-axis, and wherein the convex contact portion is such that the central mid-axis of the piston rod in any position of the piston rod between the first end position and the second end position is inclined at an angle with respect to the trimming plate, wherein the angle is less than or equal to 6°.

16. The hydraulic trim device according to claim 15, wherein the angle is in a range from 1.5° to 4.5° or from 2° to 4°.

17. The hydraulic trim device according to claim 15, wherein the angle is 3°.

18. A boat motor, comprising:

a boat drive; and

a hydraulic trim device disposed on the boat drive, the hydraulic trim device comprising: a trimming cylinder having an elongate body defining a receptacle that is elongated in an axial direction along a central axis of the elongate body; a piston rod received in the receptacle of the elongate body, the piston rod shaped to be movable within the trimming cylinder with respect to the central axis between a first end position and a second end position, the piston rod having a distal contact portion that extends axially with respect to the elongate body; and a trimming plate including a base surface opposite an asymmetric contact surface that faces the piston rod, a first side surface extending orthogonally from the base surface to a first base point on the asymmetric contact surface, and a second side surface extending orthogonally from the base surface to a second base point on the asymmetric contact surface, the trimming plate positioned such that the asymmetric contact surface abuts the distal contact portion of the piston rod, wherein movement of the distal contact portion of the piston rod along the asymmetrical contact surface of the trimming plate during a movement of the piston rod between the first end position and the second end position causes movement of the hydraulic trim device.

19. A boat comprising:

a hull; and

the boat motor according to claim 18,

wherein the boat drive is pivotably arranged on the hull by the hydraulic trim device.

20. The boat according to claim 19, wherein the boat is a sports boat.