DISPLACING DEVICE
A displacement device for fluids, in particular liquids has linearly movable displacement bodies which dip into pump chambers and are connected via respectively one connecting rod to crank pins of an externally driven crank shaft, wherein at least two groups of displacement bodies are provided. All the groups each have the same number of displacement bodies and the crank pins for the displacement bodies are arranged distributed around the crank shaft at the same angular distances. The crank pins assigned to one group are arranged with respect to those of the other group each offset by an offset angle β around the crank shaft. Furthermore, the displacement bodies of each group are arranged offset in the axial direction of the crank shaft with respect to those of the other groups and the group displacement bodies are each arranged around the crank shaft at a group offset angle γ with respect to one another. The displacement device enables low pressure pulsations.
The invention relates to a displacement device for fluids, in particular liquids, comprising displacement bodies which dip linearly into the displacement device, namely into cylindrical pump chambers in a pump housing which are each in fluidic communication via a suction valve and a pressure valve, wherein the displacement bodies are each connected via a connecting rod to crank pins of an externally driven crank shaft.
Displacement pumps are known by means of which water can be brought to pressures of several hundred bar. Such pressurized water is used, for example, to descale rolled steel blocks or strips in order to achieve rolled products with high, uniform surface quality.
When using displacement pumps with linearly movable displacement bodies, hereinafter also called plungers, pressure pulsations unavoidably occur which should be kept as small as possible in order to ensured desired uniformity of the descaling of the rolled products. In conventional displacement pumps the cylinders for the displacement bodies are arranged in series in the pump housing. Studies made by the applicant have shown that in such a series arrangement the pressure pulsations become smaller with increasing odd number of cylinders than with an even number of cylinders. However, obstacles to the use of a large odd number of cylinders, e.g. seven cylinders, are the large installation length, the poor mass balance and the non-uniform loading of the crank shaft.
The invention is based on the object of providing a displacement device of the type described initially which leads to few pressure pulsations.
This object is solved by patent claim 1, wherein for a displacement device according to the invention
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- at least two groups of displacement bodies are provided,
- all the groups each have an equal number of displacement bodies,
- the crank pins for the displacement bodies are arranged distributed around the crank shaft at the same angular distances α,
- the crank pins assigned to one group are arranged around the crank shaft with respect to those of the other groups in each case offset by an offset angle β,
- the displacement bodies of each group are arranged in the axial direction of the crank shaft offset with respect to those of the other groups and
- the groups of displacement bodies are each arranged offset to one another by a group offset angle γ around the crank shaft.
A particularly compact design can be achieved here if two groups of displacement bodies are provided and the displacement bodies of one group are arranged alternately with the displacement bodies of the other group in the axial direction of the crank shaft.
With this arrangement it is possible to provide the displacement bodies in a V or boxer arrangement.
With regard to better compensation of the mass forces, it is advantageous if the two groups of displacement bodies are arranged in a boxer arrangement, wherein the group offset angle is 180° but can also be modified, e.g. can be 150°. In a boxer arrangement the stressing of the crank shaft is minimized compared to a series arrangement with an odd number of displacement bodies.
In a displacement device designed with two groups of displacement bodies according to the invention, each group comprises three displacement bodies each arranged at the angular distance α of 120° distributed around the crank shaft. An offset angle β of 30° of the crank pins assigned to the first group with respect to those of the second group results in a particularly low pressure pulsation here.
The formulated object can also be solved by a displacement device of the type described initially in which
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- a drive is provided with two opposite output shaft ends to which respectively one crank shaft of a displacement pump is coupled, which in each case comprises a group of displacement bodies,
- the two groups of displacement bodies have an equal number of displacement bodies,
- the crank pins for the displacement bodies of each group are arranged offset with respect to one another around the appurtenant crank shaft at the same angular distances α and
- the crank pins of one group are arranged offset with respect to those of the other group by an offset angle β around the appurtenant crank shaft.
Further advantageous embodiments of the invention with a common drive for two displacement pumps are specified in subclaims 7 to 12.
The invention is explained in detail hereinafter with reference to schematic drawings with further details. In the figures:
The crank shaft 10 and the plungers 1 to 6 form part of a displacement pump whose housing and further parts are not shown; it is understood however that the plungers 1 to 6 are guided in a slidable and sealed manner in cylindrical pump chambers of the usual design, wherein the pump chambers are in fluidic communication via respectively one suction valve and one pressure valve in order to bring a fluid, e.g. water to high pressures.
In the uppermost diagram in
Plungers at the upper dead point OT or lower dead point UT have the speed zero, and therefore intersect the crank angle axis x. Here the conveying process begins or ends. For example, the plunger 1 is located at crank angle zero in UT and begins to convey with increasing conveying quantity. The plunger 2 is already located in the conveying state with increasing conveying quantity at crank angle zero.
At crank angle 60° according to
At 90° plunger 1 conveys at the highest speed at maximum capacity whilst plunger 6 has reached the speed 0 m/s in OT etc.
Curve f in the middle diagram of
Finally curve d in the lowest diagram in
This constitutes a very low pressure pulsation which is small than that which can be achieved with a conventional displacement pump with seven pumps in series.
As
The invention is not restricted to the embodiments shown. Thus, each plunger group of one embodiment according to
The features disclosed in the preceding description, the claims and the drawings can be important, both individually and in any combination, for the implementation of the invention in its various configurations.
REFERENCE LIST
- A, B Plunger group
- 1 to 6 Displacement body, plunger
- 10 Crank shaft
- 11 to 16 Crank pin
- 17 Drive end
- 18, 19 Bearing boss
- 20 Connecting rod
- 21 Cross head
- α Angular distance of the plungers of one group
- β Offset angle of the crank pins of one group to those of the other group
- γ Group offset angle of the plunger groups
- 30 Electric motor
- 31, 32 Displacement pump
- 34 Output shaft end
- E, F Plane
- x Crank angle axis
- f Conveying quantity curve
- d Pressure pulsation curve
- g1 to g6 Speed curves
Claims
1. A displacement device for fluids, in particular liquids, comprising linearly movable displacement bodies which dip into the displacement device and are each connected via a connecting rod to crank pins of an externally driven crank shaft, wherein
- at least two groups (A; B) of displacement bodies are provided,
- all the groups each have an equal number of displacement bodies,
- the crank pins for the displacement bodies are arranged distributed around the crank shaft at the same angular distances (α),
- the crank pins assigned to one group (B) are arranged around the crank shaft with respect to those of the other groups (B) in each case offset by an offset angle (β),
- the displacement bodies of each group (B) are arranged in the axial direction of the crank shaft offset with respect to those of the other groups (A) and
- the groups (A; B) of displacement bodies are each arranged offset to one another by a group offset angle (γ) around the crank shaft.
2. The displacement device according to claim 1, characterized in that two groups (A; B) of displacement bodies are provided and that the displacement bodies of one group (B) are arranged alternately with the displacement bodies of the other group (A) in the axial direction of the crank shaft.
3. The displacement device according to claim 2, characterized in that the two groups (A; B) of displacement bodies are arranged in a boxer arrangement, wherein the group offset angle (γ) is 180°.
4. The displacement device according to claim 1, characterized in that each group comprises three displacement bodies each arranged at the angular distance (α) of 120°.
5. The displacement device according to claim 1, characterized in that the offset angle (β) is 30°.
6. A displacement device for fluids, in particular liquids, comprising linearly movable displacement bodies which dip into the displacement device and are each connected via a connecting rod to crank pins of an externally driven crank shaft, wherein
- a drive is provided with two opposite output shaft ends to which respectively one crank shaft of a displacement pump is coupled, which in each case comprises a group (A; B) of displacement bodies,
- the two groups (A; B) of displacement bodies have an equal number of displacement bodies,
- the crank pins for the displacement bodies (A; B) of each group are arranged offset with respect to one another around the appurtenant crank shaft at the same angular distances (α); and
- the crank pins of one group (B) are arranged offset with respect to those of the other group (A) by an offset angle (β) around the appurtenant crank shaft.
7. The displacement device according to claim 6, characterized in that the output shafts and the crank shafts are aligned with one another.
8. The displacement device according to claim 6, characterized in that the two groups (A; B) of displacement bodies are arranged offset with respect to one another around the crank shafts by a group offset angle (γ).
9. The displacement device according to claim 6, characterized in that each group (A; B) comprises three displacement bodies which are each arranged distributed around the appurtenant crank shaft at the angular distance (α) of 120°.
10. The displacement device according to claim 6, characterized in that the offset angle (β) of the crank pins of each crank shaft is 30°.
11. The displacement device according to claim 6 characterized in that the drive is an electric motor.
12. The displacement device according to claim 11, characterized in that the electric motor has two opposite output shaft ends which are aligned with one another and which form the end parts of a continuous electric motor shaft.
Type: Application
Filed: Sep 11, 2014
Publication Date: Sep 28, 2017
Inventor: Juergen GAYDOUL (Taeby)
Application Number: 15/509,379