SELF-BLEEDING DOUBLE ACTION HYDRAULIC CYLINDER

Abstract

A self-bleeding hydraulic cylinder system is provided. The system includes a hydraulic cylinder with an inner wall and an outer wall. A cylinder port is located in a top region of the hydraulic cylinder. A line port is located in a bottom region of the hydraulic cylinder. A sleeve covers at least a portion of the outer wall of the hydraulic cylinder, and a channel is formed between the sleeve and the outer wall of the hydraulic cylinder. The channel extends from the cylinder port to the line port such that air within the hydraulic cylinder is pushed through the cylinder port and through the channel to the line port in response to actuation of the hydraulic cylinder.

Description

FIELD OF THE INVENTION

This invention relates to hydraulic cylinder systems and in particular to hydraulic cylinders capable of purging air from the system through normal actuation of the cylinder piston.

BACKGROUND

In conventional hydraulic systems, proper operation depends on the ability to purge all compressible compounds from the system. Air is an example of a compressible compound that must be purged from a hydraulic system to ensure proper operation. The entrapment of air in the system or the dissolving of gas into hydraulic fluid may be problematic. Pressure drops, cavitation, reduced functionality, or general harm to the system may occur due to the presence of entrapped or dissolved air. As a result, air must be purged from hydraulic systems to ensure proper operation.

Current approaches rely on the positioning of system components, the use of a vacuum, or continuous operation to purge air from the system. One approach purges all air from the system through the creation a vacuum. Only once a sufficient vacuum is achieved is hydraulic fluid then added to the system. However, this approach requires specialized equipment for the creation of a vacuum. Another approach simply operates the hydraulic system for a period of time whereby the fluid moving through the system will push the air to a place in the system where it can then be purged. However, these approaches may not be feasible where the hydraulic cylinder is positioned near a high point of the hydraulic system.

Hydraulic cylinders may purge air from the system by placing hydraulic lines on top of the hydraulic cylinder. This allows the cylinder to push air that has risen to the top of the system through the ports before the hydraulic fluid. Thus, any air entrapped in the system will enter the hydraulic lines first and be pushed to a point where it can then be purged.

However, space constraints may prevent the positioning of hydraulic lines at the top of the system. As a result, the hydraulic ports and lines may need to be located on the bottom of the hydraulic cylinder. In this case, actuating the cylinder will push hydraulic fluid through the ports and lines before the air that has risen to the top of the system. As a result, air may not be sufficiently purged from the system. Because fluid was pushed through the hydraulic ports before the air, the air may remain in the hydraulic lines and return to the cylinder when the cylinder is actuated in the opposite direction. Alternatively, air may also become dissolved into the hydraulic fluid in systems where fluid is pushed from the hydraulic cylinder before air. Thus, there exists a need for a hydraulic cylinder having ports and hydraulic lines located on the bottom of the hydraulic cylinder that is also capable of purging air from the system through normal actuation of the cylinder.

SUMMARY

A self-bleeding hydraulic cylinder system is provided. The system includes a hydraulic cylinder with an inner wall and an outer wall. A cylinder port is located in a top region of the hydraulic cylinder. A line port is located in a bottom region of the hydraulic cylinder. A sleeve covers at least a portion of the outer wall of the hydraulic cylinder, and a channel is formed between the sleeve and the outer wall of the hydraulic cylinder. The channel extends from the cylinder port to the line port such that air within the hydraulic cylinder is pushed through the cylinder port and through the channel to the line port in response to actuation of the hydraulic cylinder.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of an example self-bleeding hydraulic cylinder system.

FIG. 2 is a cross-sectional side view of an example self-bleeding hydraulic cylinder system installed in a housing and connected to a pump and motor.

FIG. 3 is a close-up cross-sectional view of an alternative example cylinder and sleeve configuration.

FIG. 4 is a close-up cross-sectional view of another alternative example cylinder and sleeve configuration.

DETAILED DESCRIPTION

A self-bleeding, double-action hydraulic cylinder system is described herein. In particular, the hydraulic cylinder system purges air from the cylinder through normal actuation of a cylinder piston.

As shown herein, a self-bleeding hydraulic cylinder system has a hydraulic cylinder with a cylinder port located in the top region of the hydraulic cylinder. A sleeve that functions as a manifold is used to cover the cylinder port. A line port is located in a bottom region of the hydraulic cylinder system, and a channel is formed between the hydraulic cylinder and the sleeve. The channel, for example, may be a groove formed in an outer wall of the cylinder, or alternatively formed in an interior wall of the sleeve. Upon actuation of the hydraulic cylinder, air may be pushed through the cylinder port and through the channel to the line port. A hydraulic line leading to a pump and motor may also be connected to the line port of the sleeve. The hydraulic cylinder system may be mounted in a housing above pump or motor devices and beneath a top wall of the housing.

Referring to FIG. 1, a cross-section of a hydraulic cylinder system 10 is shown. Hydraulic cylinder system 10 is divided into a top region 12 and a bottom region 14 and includes hydraulic cylinder 16 and sleeve 18. Top region 12 includes sites on the top half of the hydraulic cylinder 16. Bottom region 14 includes sites on the bottom half of hydraulic cylinder 16.

Hydraulic cylinder 16 may be any type of hydraulic cylinder known to those skilled in the art and may include a piston 17 to move hydraulic fluid and air within the cylinder. Hydraulic cylinder 16 also includes cylinder port 20 located in top region 12 of hydraulic cylinder system 10. In one embodiment, cylinder port 20 is located proximate to the top of hydraulic cylinder 16 and is formed from inner wall 22 to outer wall 24 of the hydraulic cylinder.

Sleeve 18 functions as a manifold, providing a space through which air and hydraulic fluid may pass. Additionally, sleeve 18 may be made from the same material as outer wall 24 of hydraulic cylinder 16 or any other suitable material. In an embodiment, sleeve 18 may be made of metal and welded to hydraulic cylinder 16. Sleeve 18 includes line port 26 located in bottom region 14 of hydraulic cylinder system 10. In one embodiment, line port 26 may be located proximate to the bottom of hydraulic cylinder 16 and is formed from exterior wall 28 to interior wall 30 of sleeve 18.

Channel 32 is formed when sleeve 18 encloses cylinder port 20 of hydraulic cylinder 16. Channel 32 also extends from cylinder port 20 to line port 26. When hydraulic cylinder 16 is actuated, sleeve 18 functions as a manifold allowing air and fluid to pass through cylinder port 20 and channel 32 to line port 26 as illustrated by arrows 25. In one embodiment, channel 32 may be a groove 34 formed in outer wall 24 of hydraulic cylinder 16, as seen in FIG. 2. In another embodiment, channel 32 may be comprised of groove 34 formed in interior wall 30 of sleeve 18, as seen in FIG. 3. In yet another embodiment, channel 32 may be comprised of groove 34 formed in both outer wall 24 of hydraulic cylinder 16 and interior wall 30 of sleeve 18, as seen in FIG. 4.

As seen in FIG. 1, groove 34 extends along the circumference of at least one of side 36 of hydraulic cylinder 16. In particular, in the embodiment of FIG. 1, groove 34 is shown extending along the circumference of both sides 36 of hydraulic cylinder 16. Groove 34 may also be milled into outer wall 24 of hydraulic cylinder 16 or may be formed in interior wall 30 of sleeve 18.

When hydraulic cylinder system 10 is in use, hydraulic line 38 may be attached to line port 26. Line port 26 may be formed in any manner known to those skilled in the art to allow the attachment of hydraulic line 38. When hydraulic cylinder 16 is actuated (during piston movement, for example), air and fluid flowing through channel 32 to line port 26 will exit the channel through the line port and enter hydraulic line 38 as illustrated by arrows 25.

Referring now to FIG. 2, a hydraulic cylinder system 10 is shown positioned in a housing 40 above a pump 42, vented reservoir 43, and motor 44 to which the hydraulic cylinder system is attached. As seen in FIG. 2, example hydraulic cylinder system 10 includes cylinder ports 20 and line ports 26 at each end of hydraulic cylinder 16. Example hydraulic cylinder 16 contains hydraulic fluid 46 and air 48, which has risen to the top of the hydraulic cylinder.

Hydraulic cylinder system 10 also includes sleeves 18 attached to each end of hydraulic cylinder 16 covering cylinder ports 20. Hydraulic lines 38 are attached to example hydraulic cylinder system 10 and lead to pump 42. Pump 42 is connected to vented reservoir 43 and motor 44. Pump 42 and motor 44 may be any pump and motor known to those skilled in the art to be suitable for use in a hydraulic system. Vented reservoir 43 is a fluid reservoir that is vented to the atmosphere.

Vented reservoir 43 may be used to account for the volumetric differences between either sides of hydraulic cylinder 16. Piston 17 includes piston head 45 and piston shaft 47. Head 45 divides the chamber of hydraulic cylinder 16 into two sides, one side including shaft 47. The side of hydraulic cylinder 16 lacking shaft 17 may hold a greater volume of fluid than the side that includes the shaft. Vented reservoir 43 may be used to contain excess fluid 46 as the side of hydraulic cylinder 16 that includes shaft 47 is filled to capacity.

Vented reservoir 43 is also used as the bleed site for any air present in the system. Because cylinder ports 20 are located in top region 12 of hydraulic cylinder system 10, air 48 will be pushed through cylinder ports 20 before hydraulic fluid 46. By pushing air 48 from hydraulic cylinder 16 before hydraulic fluid 46, the air ultimately be pushed to reservoir 43 at which point it will be purged from the system to the atmosphere.

As seen in FIG. 2, motor 44 powers pump 42, which pushes hydraulic fluid 46 through one of hydraulic lines 38. Hydraulic fluid 46 exits one of hydraulic lines 38 into corresponding channel 32 where it then travels to corresponding cylinder port 20 and enters hydraulic cylinder 16 actuating piston 17. As hydraulic cylinder 16 is actuated, air 48 is pushed through opposite cylinder port 20 followed by hydraulic fluid 46. Air 48 leads hydraulic fluid 46 through corresponding channel 32 to corresponding line port 26 and into corresponding hydraulic line 38. Air 48 then leads fluid 46 through pump 42 to vented reservoir 43. Air 48 may then bubble through any fluid 46 present in vented reservoir 43 escaping to the atmosphere.

Also shown in FIG. 2, hydraulic cylinder system 10 in this example may be positioned at or just below top wall 50 of housing 40. Top wall 50 may be an upper barrier of housing 40, or top wall 50 may be another component also installed in housing 40. In other embodiments, top wall 50 may be other walls or barriers of housing 40. As seen in the example in FIG. 2, adequate space to allow for the attachment of hydraulic lines to the top of the hydraulic cylinder is not achieved because hydraulic cylinder 16 is placed at a high point within housing 40 adjacent to top wall 50. Sleeve 18 functions as a manifold creating channel 32 between outer wall 24 of hydraulic cylinder 16 and interior wall 30 of the sleeve. This allows hydraulic lines 38 to be attached to the bottom of hydraulic cylinder 16 while still positioning cylinder ports 20 at the top of the hydraulic cylinder.

By way of example, the hydraulic cylinder system described herein may be installed in the housing of a vehicle door system. In an example vehicle door system, the hydraulic cylinder system may need to be positioned above the pump and motor and just below the top wall of the housing leaving little room for top-mounted hydraulic lines. In this example system, because the hydraulic cylinder is positioned at the highest point of the system, air may rise to the top of the cylinder. The hydraulic cylinder system described herein allows the installation of a hydraulic cylinder below the top wall of the housing and above the pump and motor with bottom-mounted hydraulic lines. The sleeve encloses the top-positioned cylinder ports and forms a channel to the bottom-positioned line ports. This allows air to be pushed from the hydraulic cylinder before the hydraulic fluid to a point at which it can be purged. Thus, air may be bled from the hydraulic cylinder system through normal actuation of the hydraulic cylinder without the need for special equipment or processes.

The invention illustratively disclosed herein suitably may be practiced in the absence of any element, part, step, component, or ingredient which is not specifically disclosed herein.

While in the foregoing detailed description this invention has been described in relation to certain preferred embodiments thereof, and many details have been set forth for purposes of illustration, it will be apparent to those skilled in the art that the invention is susceptible to additional embodiments and that a certain of the details described herein can be varied considerably without departing from the basic principles of the invention.

Claims

1. A self-bleeding hydraulic cylinder system comprising:

a hydraulic cylinder having an inner wall and an outer wall;

a cylinder port located in a top region of the hydraulic cylinder;

a line port located in a bottom region of the hydraulic cylinder;

a sleeve covering at least a portion of the outer wall of the hydraulic cylinder; and

a channel formed between the sleeve and the outer wall of the hydraulic cylinder, the channel extending from the cylinder port to the line port such that air within the hydraulic cylinder is pushed through the cylinder port and the channel to the line port in response to actuation of the hydraulic cylinder.

2. The self-bleeding hydraulic cylinder system of claim 1 wherein the channel comprises a groove formed at the outer wall of the hydraulic cylinder.

3. The self-bleeding hydraulic cylinder system of claim 2 wherein the groove is milled in the outer wall of the hydraulic cylinder.

4. The self-bleeding hydraulic cylinder system of claim 1 wherein the channel comprises a groove formed at an interior wall of the sleeve.

5. The self-bleeding hydraulic cylinder of claim 1 wherein the channel comprises a groove formed at least one of: (a) the outer wall of the hydraulic cylinder; and (b) an interior wall of the sleeve.

6. The self-bleeding hydraulic cylinder system of claim 5 wherein the groove extends between the cylinder port and the line port along a circumference of at least one side of the hydraulic cylinder.

7. The self-bleeding hydraulic cylinder system of claim 5 wherein the groove extends along the circumference of both sides of the hydraulic cylinder between the cylinder port and the line port.

8. The self-bleeding hydraulic cylinder system of claim 1 wherein the cylinder port provides an opening extending from the inner wall of the hydraulic cylinder to the outer wall of the hydraulic cylinder.

9. The self-bleeding hydraulic cylinder system of claim 1 wherein the line port provides an opening extending from an inner wall of the sleeve to an outer wall of the sleeve.

10. The self-bleeding hydraulic cylinder system of claim 9 wherein the line port is positioned proximate to a bottom end of the channel.

11. The self-bleeding hydraulic cylinder system of claim 10 further comprising at least one hydraulic line coupled with the line port, the at least one hydraulic line in communication with a pump of the self-bleeding hydraulic cylinder system.

12. The self-bleeding hydraulic cylinder system of claim 10 wherein the hydraulic cylinder is positioned above a pump or motor of the self-bleeding hydraulic cylinder system.

13. The self-bleeding hydraulic cylinder system of claim 10 wherein the hydraulic cylinder is confined within a housing and wherein the hydraulic cylinder is positioned adjacent to a wall of the housing.

14. The self-bleeding hydraulic cylinder system of claim 10 wherein the hydraulic cylinder is contained within a housing of a vehicle door system and wherein the top of the hydraulic cylinder is positioned adjacent to a wall of the housing.

15. The self-bleeding hydraulic cylinder system of claim 10 wherein the sleeve is welded to at least one end of the hydraulic cylinder.

16. The self-bleeding hydraulic cylinder system of claim 1 wherein the sleeve completely encloses at least one end of the hydraulic cylinder about the circumference of the at least one end of the hydraulic cylinder.

17. The self-bleeding hydraulic cylinder system of claim 16 wherein a pair of sleeves are respectively positioned at each end of the hydraulic cylinder.