Variable displacement hydraulic machine
By employing a variable displacement hydraulic machine design in a variable displacement hydraulic machine, the servo piston can be replaced without changing the relative orientation by utilizing the housing and end cap design. This solves the problem of differences in component configuration and assembly steps in the prior art, and achieves flexible switching of displacement levels and cost reduction.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- DANFOSS POWER SOLUTIONS APS
- Filing Date
- 2025-09-18
- Publication Date
- 2026-06-12
AI Technical Summary
Existing variable displacement hydraulic machines exhibit significant differences in component configuration and assembly steps when switching from the minimum displacement level to the maximum displacement level or vice versa, leading to increased complexity and cost.
The machine employs a variable displacement hydraulic design, where the housing and end cap design allows for switching of displacement levels by replacing the maximum or minimum displacement bias servo piston without altering their relative orientation, simplifying the assembly process.
It enables switching of displacement levels by replacing a single component without changing the relative orientation of the housing and end caps, reducing complexity and cost, and is suitable for hydraulic machines under different bias conditions.
Smart Images
Figure CN122191036A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates generally to variable displacement hydraulic machines, and particularly to variable displacement hydraulic machines configurable to a minimum displacement bias level and a maximum displacement bias level, as well as to a method of assembling such a variable displacement hydraulic machine. Background Technology
[0002] Variable displacement hydraulic machines (such as hydraulic pumps or hydraulic motors) are known. It is further known that the displacement level of a variable hydraulic machine can be configured to vary as needed or desired. The displacement level of a variable hydraulic machine can be biased to a minimum displacement level, and therefore, an actuating force is required to change the displacement level of the variable hydraulic machine to a maximum displacement level, or some level between the minimum and maximum displacement. The displacement level of a variable hydraulic machine can be biased to a maximum displacement level, and therefore, an actuating force is required to change the displacement level of the variable hydraulic machine to a minimum displacement level, or some level between the maximum and minimum displacement.
[0003] Although it is known that variable displacement hydraulic machines can be configured to be biased to the minimum displacement level or to the maximum displacement level, the differences in component configuration and assembly steps between the machine being biased to the minimum displacement level and to the maximum displacement level are substantial. Summary of the Invention
[0004] The present invention provides a variable displacement hydraulic machine and an assembly method thereof, which advantageously allows the variable displacement hydraulic machine to be configured by changing individual components.
[0005] According to some embodiments of the present invention, a variable displacement hydraulic machine includes a housing and an end cap connected to the housing and defining an internal volume. The machine also includes a maximum displacement bias servo piston or a minimum displacement bias servo piston, which is at least partially disposed within the internal volume of the end cap. The end cap is configured such that the maximum displacement bias servo piston and the minimum displacement bias servo piston can be disposed at servo piston positions within the internal volume. When the maximum displacement bias servo piston is disposed at the servo piston position, the variable displacement hydraulic machine is horizontally biased towards the maximum displacement. When the minimum displacement bias servo piston is disposed at the servo piston position, the variable displacement hydraulic machine is horizontally biased towards the minimum displacement.
[0006] In some embodiments, the variable displacement hydraulic machine includes a housing and an end cap connected to the housing, the end cap defining an internal volume. The end cap is configured to at least partially arrange a maximum displacement bias servo piston and a minimum displacement bias servo piston at servo piston positions within the internal volume. When the maximum displacement bias servo piston is arranged at the servo piston position, the variable displacement hydraulic machine is horizontally biased toward the maximum displacement, and when the minimum displacement bias servo piston is arranged at the servo piston position, the variable displacement hydraulic machine is horizontally biased toward the minimum displacement.
[0007] In some embodiments, a method of assembling a variable displacement hydraulic machine includes: providing an end cap defining an internal volume; determining whether the variable displacement hydraulic machine is to be configured for maximum displacement horizontal bias or minimum displacement horizontal bias; selecting a maximum displacement bias servo piston when the determination step determines that the variable displacement hydraulic machine is to be configured for maximum displacement horizontal bias, and selecting a minimum displacement bias servo piston when the determination step determines that the variable displacement hydraulic machine is to be configured for minimum displacement horizontal bias; arranging the selected maximum displacement bias servo piston or the selected minimum displacement bias servo piston at least partially within the internal volume at a servo piston position; and connecting the end cap to a housing. Attached Figure Description
[0008] Figure 1A This is a left-side cross-sectional view showing a prior art variable displacement hydraulic machine configured to be biased to the maximum displacement level;
[0009] Figure 1B yes Figure 1A Left view of a prior art variable displacement hydraulic machine;
[0010] Figure 1C yes Figure 1A A front view of a prior art variable displacement hydraulic machine;
[0011] Figure 2A yes Figure 1A A left-side sectional view of a prior art variable displacement hydraulic machine, but configured to be biased to the minimum displacement level;
[0012] Figure 2B yes Figure 2A Left view of a prior art variable displacement hydraulic machine;
[0013] Figure 2C yes Figure 2A A front view of a prior art variable displacement hydraulic machine;
[0014] Figure 3A This is a left sectional view showing a variable displacement hydraulic machine according to the invention, configured to be biased to the maximum displacement level;
[0015] Figure 3B yes Figure 3A A left-side sectional view of a variable displacement hydraulic machine, in which a servo piston is moved to the actuated position;
[0016] Figure 4A This is a left-side cross-sectional view of a variable displacement hydraulic machine according to the invention, configured to be biased to a minimum displacement level;
[0017] Figure 4B yes Figure 4A A left-side sectional view of a variable displacement hydraulic machine, in which a servo piston is moved to the actuated position. Detailed Implementation
[0018] Before proceeding with a detailed description of the various embodiments, it should be understood that the invention is not limited to the specific embodiments described. It should also be understood that the technical terminology used is for the purpose of describing particular embodiments only and is not intended to limit the scope of the claims of this application.
[0019] refer to Figures 1A-1C The image illustrates a prior art variable displacement hydraulic machine 10 configured to be biased towards the maximum displacement level. The prior art machine 10 includes an end cap 12, a housing 14, and an actuator 16, wherein the actuator 16 has an electroproportional control element 18 operating in conjunction with a spring 19. The housing 14 defines a first fluid port 20A and a second fluid port 20B.
[0020] A variable displacement hydraulic machine 10 configured to bias towards the maximum displacement means that actuation force from actuator 16 is required to change the displacement level to a smaller displacement level, such as changing the displacement level to the minimum displacement level or some displacement level in between. In this configuration, the electro-proportional control element 18 and the spring 19 are shown extending toward the bottom of the machine 10 (from...). Figures 1A-1C From the perspective of ( ), and the first port 20A is located on the right side of machine 10, and the second port 20B is located on machine 10 ( Figure 1C () on the left side.
[0021] refer to Figures 2A-2C , showed Figures 1A-1C The prior art variable displacement hydraulic machine 10 is shown, but reconfigured to be horizontally biased towards the minimum displacement. This reconfiguration of the prior art machine 10 requires reversing the orientation of the actuator 16, such that the electroproportional control element 18 and the spring 19 are shown extending towards the top of the machine 10 (from...). Figures 2A-2C From the perspective of ( ), and the first port 20A is located on the left side of machine 10, and the second port 20B is located on machine 10 ( Figure 2C The right side of the end cap 12 rotates to accommodate the reconfigured displacement level bias.
[0022] refer to Figure 3A and Figure 3B According to an embodiment of the present invention, a variable displacement hydraulic machine 100 configured to be biased to a maximum displacement level is shown. The machine 100 includes an end cap 112 defining an internal volume 113, which is connected to a housing 114. The machine 100 includes a maximum displacement bias servo piston 122A and a piston spring 124, wherein the maximum displacement bias servo piston 122A is disposed at a servo piston position within the internal volume 113 of the end cap 112, and the piston spring 124 is arranged to bias the maximum displacement bias servo piston 122A to a maximum displacement position, which is as follows: Figure 3A The position is shown in the diagram. At the maximum displacement position, the maximum displacement bias servo piston 122A moves the swashplate 123 to the maximum displacement position. At this maximum displacement position, the machine 100 outputs the maximum amount of fluid in each stroke. The maximum amount of fluid in each stroke can be determined by the maximum angle at which the swashplate can tilt, thereby setting the upper limit of the fluid that the machine 100 can output in each stroke.
[0023] The maximum displacement bias servo piston 122A has a contact surface 126A, which is configured to rest on the mounting surface 128 of the end cap 112. When the contact surface 126A of the maximum displacement bias servo piston 122A is resting on the mounting surface 128 (e.g. Figure 3B As shown), the displacement device (e.g., swashplate) of machine 100 is moved to the minimum displacement position. At this minimum displacement position, machine 100 outputs a minimum amount of fluid in each stroke. Machine 100 is arranged such that the actuation force moves the maximum displacement bias servo piston 122A to... Figure 3B The position shown or any position in between.
[0024] refer to Figure 4A and Figure 4B , showed Figure 3A and Figure 3B The variable displacement hydraulic machine 100, according to an embodiment of the invention, is configured to be horizontally biased toward the minimum displacement. Except that the maximum displacement biased servo piston 122A is replaced by the minimum displacement biased servo piston 122B at the servo piston position, the machine 100 is... Figure 3A and Figure 3B The same as machine 100. Piston spring 124 is arranged to bias the minimum displacement bias servo piston 122B to the minimum displacement position, which is as follows: Figure 4AThe position is shown. At the minimum displacement position, the minimum displacement bias servo piston 122B moves the displacement device (e.g., swashplate) of the machine 100 to the minimum displacement position. At this minimum displacement position, the machine 100 outputs a minimum amount of fluid in each stroke. The minimum amount of fluid in each stroke can cover periods with no fluid output in each stroke.
[0025] The minimum displacement bias servo piston 122B has a contact surface 126B, which is configured to rest on the mounting surface 128 of the end cap 112. When the contact surface 126B of the minimum displacement servo piston 122B is mounted on the mounting surface 128 (e.g. Figure 4B As shown), the displacement device (e.g., swashplate) of machine 100 is moved to the maximum displacement position. At this maximum displacement position, machine 100 outputs the maximum amount of fluid in each stroke. Machine 100 is arranged such that the actuation force moves the minimum displacement bias servo piston 122B to... Figure 4B The position shown or any position in between.
[0026] The same end cap 112 defines an internal volume 113 such that the internal volume 113 is configured to receive the maximum displacement bias servo piston 122A and the minimum displacement bias servo piston 122B. It should be understood that the end cap 112 being configured to receive "both" pistons 122A and 122B should not be construed as meaning that the end cap 112 simultaneously receives or accommodates both pistons 122A and 122B. Rather, the end cap 112 being configured to receive or accommodate both pistons 122A and 122B means that pistons 122A and 122B are interchangeable within the end cap 112 to allow for changes in the displacement horizontal bias configuration of the machine 100.
[0027] When machine 100 is configured for such Figure 3A and Figure 3B The maximum displacement horizontal bias shown and when machine 100 is configured for such Figure 4A and Figure 4B When the minimum displacement horizontal bias is shown, the end cap 112 has the same relative orientation with respect to the housing 114. In other words, it is not necessary to... Figures 1A-2C As required in the prior art machine 10, the end cap 112 is rotated to change the displacement level bias of the machine 100. After the end cap 112 is attached to the housing 114, the orientation and position of the end cap 112 relative to the housing 114 are the same, regardless of whether the maximum displacement bias servo piston 122A or the minimum displacement bias servo piston 122B is selected and arranged at the servo piston position within the internal volume 113 of the end cap 112.
[0028] Although Figures 3A-4B The hydraulic machine 100 shown is used as a motor, but the principle of displacement bias is equally applicable to pump applications.
[0029] The range of motion of the displacement device in a variable displacement hydraulic machine can be virtually any range required or desired in the current application. For example, but not limited to: the range of motion of the maximum displacement horizontally biased configuration can be 18° swashplate angle when unpressurized (i.e., not actuated by an actuating force), and the range of motion can be 0° swashplate angle when pressurized, and vice versa for the minimum displacement horizontally biased configuration; the range of motion of the minimum displacement horizontally biased configuration can be 0° swashplate angle when unpressurized, and 18° swashplate angle when pressurized.
[0030] Advantageously, the variable displacement hydraulic machine and the method of assembling it offer benefits to both the customer / user and the manufacturer. For example, the customer / user experiences no difference in the machine's housing (or casing), as the same housing and / or end caps are used for both minimum and maximum displacement level-biased machines. Therefore, the customer / user does not need to consider variations in size and / or shape based on the selected bias state of the variable displacement hydraulic machine. Furthermore, the customer does not need to consider differences in port location, as the port locations are identical regardless of the selected bias state. Moreover, when desired, the customer / user can change the bias state of the variable displacement hydraulic machine by replacing individual components, reducing complexity and cost, rather than being the primary factor in deciding whether to change the bias state.
[0031] For manufacturers, cost reduction and complexity are achieved by manufacturing variable displacement hydraulic machines and utilizing the assembly method of this invention. Manufacturers can change only individual components during the manufacturing process, depending on whether the customer orders a minimum or maximum bias machine. Manufacturers do not need to store and select between different housing and / or end cap designs to accommodate different bias states. Furthermore, manufacturers will achieve cost reduction because the assembly method for different machine bias states is essentially the same; the only difference lies in the selection of individual components. Additionally, manufacturers can use the same assembly tools to assemble both configurations, which also reduces cost and complexity.
[0032] While one of the advantages of the variable displacement hydraulic machine and assembly method described in this invention is that only one component (i.e., servo pistons 122A, 122B) needs to be replaced, it is also within the scope of this invention to replace or substitute other components when needed or desired. For example, in some embodiments, in addition to replacing servo pistons 122A, 122B, the swashplate of the hydraulic machine may also be replaced or modified.
[0033] As will be recognized by those skilled in the art, many changes and modifications can be made to the above embodiments of the invention without departing from the spirit of the invention as defined in the appended claims. Therefore, the specific embodiments described are to be considered illustrative rather than restrictive.
Claims
1. A variable displacement hydraulic machine, comprising: case; and An end cap connected to the housing, the end cap defining an internal volume; and A maximum displacement bias servo piston or a minimum displacement bias servo piston, wherein the maximum displacement bias servo piston or the minimum displacement bias servo piston is at least partially arranged within the internal volume; The end cap is configured such that the maximum displacement bias servo piston and the minimum displacement bias servo piston can be positioned at the servo piston locations within the internal volume; and When the maximum displacement bias servo piston is positioned at the servo piston location, the variable displacement hydraulic machine is horizontally biased towards the maximum displacement; and Specifically, when the minimum displacement bias servo piston is positioned at the servo piston location, the variable displacement hydraulic machine is horizontally biased toward the minimum displacement.
2. The variable displacement hydraulic machine according to claim 1, wherein the variable displacement hydraulic machine is a motor.
3. The variable displacement hydraulic machine according to claim 1, wherein the variable displacement hydraulic machine is a pump.
4. The variable displacement hydraulic machine of claim 1, wherein the maximum displacement bias servo piston or the minimum displacement bias servo piston has a contact surface configured to contact the mounting surface of the end cap at the actuated position.
5. The variable displacement hydraulic machine according to claim 1, wherein, When the maximum displacement bias servo piston is positioned at the servo piston location and when the minimum displacement bias servo piston is positioned at the servo piston location, the end cap has the same relative orientation and relative position with respect to the housing.
6. The variable displacement hydraulic machine according to claim 1, further comprising a first port position and a second port position, wherein, When the maximum displacement bias servo piston is positioned at the servo piston position and when the minimum displacement bias servo piston is positioned at the servo piston position, the first port position and the second port position are the same.
7. The variable displacement hydraulic machine according to claim 1 further includes a piston spring, wherein the piston spring biases the maximum displacement bias servo piston or the minimum displacement bias servo piston.
8. The variable displacement hydraulic machine according to claim 1 further includes a swashplate, wherein, When the maximum displacement bias servo piston is positioned at the servo piston location without any actuation force applied to it, the swashplate is biased toward the maximum displacement position.
9. The variable displacement hydraulic machine according to claim 8, wherein, When the swashplate is at the maximum displacement position, the swashplate forms an 18° angle.
10. The variable displacement hydraulic machine according to claim 1, further comprising a swashplate, wherein, When the minimum displacement bias servo piston is positioned at the servo piston location, the swashplate is biased toward the minimum displacement position.
11. The variable displacement hydraulic machine according to claim 10, wherein, When in the minimum displacement position, the swashplate forms a 0° angle.
12. A variable displacement hydraulic machine, comprising: case; and An end cap is attached to the housing, the end cap defining an internal volume; and The end cap is configured to interchangeably, at least partially, arrange the maximum displacement bias servo piston and the minimum displacement bias servo piston at the servo piston positions within the internal volume; and When the maximum displacement bias servo piston is positioned at the servo piston location, the variable displacement hydraulic machine is horizontally biased towards the maximum displacement; and Specifically, when the minimum displacement bias servo piston is positioned at the servo piston location, the variable displacement hydraulic machine is horizontally biased toward the minimum displacement.
13. The variable displacement hydraulic machine according to claim 12, further comprising a swashplate, wherein, When the maximum displacement bias servo piston is positioned at the servo piston location without any actuation force applied to it, the swashplate is biased toward the maximum displacement position.
14. The variable displacement hydraulic machine according to claim 12, further comprising a swashplate, wherein, When the minimum displacement bias servo piston is positioned at the servo piston location, the swashplate is biased toward the minimum displacement position.
15. The variable displacement hydraulic machine according to claim 12, wherein, When the maximum displacement bias servo piston is positioned at the servo piston location and when the minimum displacement bias servo piston is positioned at the servo piston location, the end cap has the same relative orientation and relative position with respect to the housing.
16. A method for assembling a variable displacement hydraulic machine, comprising: An end cap is provided, the end cap defining an internal volume; Determine whether the variable displacement hydraulic machine will be configured for maximum displacement horizontal bias or minimum displacement horizontal bias; When the result of the determination step determines that the variable displacement hydraulic machine will be configured with maximum displacement horizontal bias, the maximum displacement bias servo piston is selected; and when the result of the determination step determines that the variable displacement hydraulic machine will be configured with minimum displacement horizontal bias, the minimum displacement bias servo piston is selected. The selected maximum displacement bias servo piston or the selected minimum displacement bias servo piston is at least partially arranged at the servo piston position within the internal volume; and Connect the end cap to the housing.
17. The method according to claim 16, wherein, After the end cap is attached to the housing, the relative orientation and position of the end cap relative to the housing are the same regardless of whether the selected maximum displacement bias servo piston or the selected minimum displacement bias servo piston is arranged at the servo piston position.