Piston mechanism for variable piston machine and variable piston machine

Abstract

The utility model relates to the technical field of hydraulic pressure, in particular to a piston mechanism for a variable piston machine and the variable piston machine. A piston mechanism for a variable piston machine comprises a piston rod, an annular protrusion extending along the end face is formed at the first end of the piston rod, the second end of the piston rod is columnar, and a mounting hole is formed in the piston rod; the plane of the sliding shoe is attached to the end face of the first end of the piston rod, and the piston rod acts on the swash plate through the sliding shoe; the second end of the piston rod extends into the lining to slide, and the piston rod is in surface contact with the lining. The utility model further provides a variable piston machine which comprises a shell and a rotating cylinder rotationally assembled in the shell. The swash plate is assembled in the shell in a deflection manner and controls the displacement of the rotating cylinder; a piston mechanism; and a variable piston. The technical problem that in the prior art, a piston mechanism adopts the spherical characteristic to adapt to angle adjustment, and consequently the leakage rate is large is solved, and the feedback precision of a feedback mechanism is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of hydraulic pressure, in particular to a piston mechanism for a variable piston machine and a variable piston machine. Background Art

[0002] In the prior art, a variable piston machine is often provided with a piston mechanism, one end of which is connected to the housing bushing of the piston machine, and the other end is connected to the swash plate mechanism. Under the action of the pressure oil in the housing bushing, the piston mechanism is subjected to force and pushes the swash plate mechanism of the variable piston machine, adjusts the tilting angle of the swash plate mechanism, and changes the volume of fluid discharged by the variable piston machine. At the same time, the piston mechanism allows the connection of a feedback mechanism, which can feedback the position or hydraulic pressure of the piston mechanism.

[0003] The existing piston mechanisms are various according to the structural differences of the variable piston machine. The variable piston machine can be divided into single-piston and double-piston variable piston machines according to the number of piston mechanisms, and the double-piston variable piston machine is the most common. For example, the document with application number EP08758514 discloses an axial piston machine with a return device, and specifically discloses: in order to adjust the inclination of the pivot bracket and thus adjust the stroke of the piston in the cylinder when the cylinder rotates, an adjustment system is arranged in the housing of the axial piston machine. The actuation system includes at least one first actuation device. The first actuation device has a first actuation piston, which defines a pressure chamber with its first end, and the pressure chamber is formed in the bottom of the can-shaped housing part. In order to form the pressure chamber, a blind hole is made in the bottom of the can-shaped housing part, and a bushing is inserted therein, which serves as a sliding surface of the first end of the actuation piston and interacts with the first end of the first actuation piston in a sealing manner. The first end of the actuation piston is not cylindrical, but has a slightly spherical shape, so that the actuation piston is tilted relative to the longitudinal axis of the bushing to prevent the bushing from tilting. The sealing ring can also be arranged in the crown area of ​​the first end of the actuating piston. A ball head is formed on the second end of the actuating piston facing away from the first end, the ball head is connected to a compression section that can transmit tension and pressure, and the return element is firmly connected to the actuating piston and supported on a large area on its outer circumference. A lubricant channel is formed inside the actuating piston in the first actuating device. The lubricant channel extends from the first end of the actuating piston to the second end. The lubricant channel thus connects the pressure chamber to the spherical head-shaped second end of the actuating piston.

[0004] The above-mentioned piston mechanism can realize oil guidance and facilitate the connection of the feedback mechanism, but the piston mechanism moves in a non-linear direction. Therefore, the first end of the brake piston is set to be slightly spherical in shape, so that the piston structure allows a certain angle adjustment when pushing the swash plate mechanism to change the inclination angle. However, this angle adjustment will cause the feedback mechanism to follow the same angle change, which will have a certain impact on the proportional characteristic control or constant torque control of the variable piston machine. In addition, there is a line contact between the spherical feature and the bushing, and the leakage is relatively large. Utility Model Content

[0005] In order to solve the technical problem in the prior art that the piston mechanism adopts spherical features to adapt to angle adjustment, resulting in large leakage, the utility model provides a piston mechanism for a variable piston machine and a variable piston machine, which solves the above technical problem and improves the feedback accuracy of the feedback mechanism.

[0006] In order to solve the above technical problems, the utility model provides a piston mechanism for a variable piston machine, comprising:

[0007] A piston rod, wherein a first end of the piston rod is formed with an annular protrusion extending along the end surface, a second end of the piston rod is columnar, and a mounting hole is formed on the piston rod;

[0008] A sliding shoe, wherein a plane of the sliding shoe is in contact with a first end surface of the piston rod, and the piston rod acts on the swash plate through the sliding shoe;

[0009] The second end of the piston rod extends into the bushing and slides therein, and the piston rod is in surface contact with the bushing.

[0010] According to an embodiment of the utility model, a ball head is formed on the swash plate, and the ball head extends into the sliding shoe for active engagement.

[0011] According to an embodiment of the present utility model, when the piston rod pushes the swash plate to move to a maximum angle, the offset distance of the axis of the sliding shoe relative to the axis of the piston rod is D1, and D1 is no greater than 2 mm.

[0012] According to an embodiment of the utility model, when the swash plate is at zero position, the second end surface of the piston rod is close to an end port of the bushing away from the sliding shoe.

[0013] According to an embodiment of the utility model, an axial center hole is formed in the piston rod, and the axial center hole is vertically connected to the mounting hole.

[0014] According to an embodiment of the utility model, an oil guide groove is formed on the second end surface of the piston rod, and the oil guide groove is communicated with the axial center hole.

[0015] According to an embodiment of the utility model, a guide sleeve and an elastic member are sleeved on the piston rod, and the elastic member is located between the guide sleeve and the first end of the piston rod.

[0016] According to an embodiment of the utility model, a retaining ring is further sleeved on the piston rod, and the retaining ring is located on a side of the guide sleeve away from the elastic member, and the retaining ring can limit the position of the guide sleeve on the piston rod.

[0017] According to one embodiment of the utility model, when the swash plate moves to the maximum angle, the distance from the first end face of the piston rod to the guide sleeve is X1, and the distance from the first end face of the piston rod to the axial midpoint of the contact portion between the piston rod and the bushing is X2, and X1 / (X2-X1)<1.

[0018] The utility model also provides a variable piston machine, comprising:

[0019] shell,

[0020] A rotary cylinder, the rotary cylinder being rotatably mounted in the housing;

[0021] A swash plate, the swash plate is mounted in the housing in a swingable manner to control the displacement of the rotary cylinder;

[0022] Piston mechanism;

[0023] A variable piston is arranged opposite to the piston mechanism to cooperate with the inclination angle of the swash plate.

[0024] Based on the above technical solution, the technical effects that can be achieved by the utility model are:

[0025] The piston mechanism for a variable piston machine of the utility model sets the shape of the piston rod and the piston rod acts on the swash plate through the sliding shoe. Since the plane of the sliding shoe fits with the first end surface of the piston rod, the sliding shoe can slide relative to the piston rod to adapt to the reaction of the piston rod when the swash plate is deflected. The piston rod can ensure axial movement without angle change. The feedback mechanism assembled on the piston rod will not produce angle change due to the deflection of the swash plate, thereby ensuring stable operation. The second end of the rod-shaped body of the piston rod can maintain surface contact with the bushing to reduce leakage.

[0026] The piston mechanism of the variable piston machine of the utility model is set to have an offset distance D1 of the axis of the sliding shoe relative to the axis of the piston rod of no more than 2 mm when the piston rod pushes the swash plate to move to the maximum angle, that is, the axis of the sliding shoe and the axis of the piston rod are almost coaxial, which can reduce the torque generated by the reaction force of the swash plate on the piston rod through the sliding shoe, thereby reducing the contact force generated between the piston rod and the bushing and the guide sleeve, thereby reducing the wear of the contact position between the piston rod and the bushing and the guide sleeve;

[0027] The piston mechanism for a variable piston machine of the utility model is set to be in zero position, and the second end face of the piston rod is close to the end port of the bushing away from the sliding shoe. Then, when in use, the inner wall of the shell can limit the inertial movement of the piston rod and prevent the swash plate from tilting to a negative swing angle. Furthermore, an oil guide groove is set on the second end face of the piston rod. Then, even if the piston rod is almost in contact with the inner wall of the shell, the oil groove can guide the pressure oil entering the bushing into the axial center hole of the piston rod.

[0028] The piston mechanism of the utility model for a variable piston machine is set such that when the swash plate moves to the maximum angle, the positional relationship between the piston rod and the guide sleeve and the bushing is X1 / (X2-X1)<1, which can make the contact force between the piston rod and the guide sleeve and the contact force between the piston rod and the bushing smaller, thereby reducing the wear of the two contact positions. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a structural schematic diagram of the piston mechanism used for the variable displacement piston machine of the utility model;

[0030] Figure 2 A schematic diagram of the structure of the piston rod and the components assembled thereon;

[0031] Figure 3 is a cross-sectional view of the piston rod;

[0032] Figure 4 This is the state diagram of the piston mechanism when the swash plate moves to the maximum angle;

[0033] Figure 5 for Figure 4 The enlarged view of the C part in FIG.

[0034] Figure 6 It is the structural diagram of the variable piston machine;

[0035] In the figure: 1-piston rod; 11-first end; 12-second end; 13-mounting hole; 14-axial center hole; 15-oil guide groove; 16-annular groove; 2-slipper; 3-bushing; 4-guide sleeve; 5-elastic member; 6-retaining ring; 7-housing; 8-rotating cylinder; 9-swash plate; 91-ball head; 10-variable piston; 20-feedback element. DETAILED DESCRIPTION

[0036] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means a limitation on the utility model and its application or use. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the utility model.

[0037] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0038] Unless otherwise specifically stated, the relative arrangement, numerical expressions and numerical values ​​of the parts and steps set forth in these embodiments do not limit the scope of the utility model. At the same time, it should be understood that, for ease of description, the sizes of the various parts shown in the accompanying drawings are not drawn according to the actual proportional relationship. The technology, method and equipment known to those of ordinary skill in the relevant art may not be discussed in detail, but in appropriate cases, the technology, method and equipment should be considered as a part of the specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters represent similar items in the following drawings, and therefore, once a certain item is defined in an accompanying drawing, it does not need to be further discussed in subsequent drawings.

[0039] In the description of the present utility model, it needs to be understood that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the drawings, and are only for the convenience of describing the present utility model and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the device or element referred to must have a specific direction or be constructed and operated in a specific direction, and therefore cannot be understood as limiting the scope of protection of the present utility model; the directional words "inside and outside" refer to the inside and outside relative to the contours of each component itself.

[0040] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used here to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figure. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figure. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0041] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. If not otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the utility model.

[0042] like Figure 1-6 As shown, this embodiment provides a piston mechanism for a variable piston machine, including a piston rod 1, a sliding shoe 2 and a bushing 3. The first end 11 of the piston rod 1 acts on the swash plate 9 through the sliding shoe 2, and the second end 12 of the piston rod 1 extends into the bushing 3. A pressure chamber is formed in the bushing 3 to introduce pressurized oil. The piston rod 1 slides along the bushing 3 under the action of the pressurized oil.

[0043] The piston rod 1 is in the shape of a rod body, and the first end 11 of the piston rod 1 is formed with an annular protrusion extending along the end surface. The end surface of the first end 11 of the piston rod 1 is flat, and the second end 12 of the piston rod 1 is columnar. The piston rod 1 is also provided with a mounting hole 13 for assembling a feedback mechanism.

[0044] As a preferred technical solution of this embodiment, an axial center hole 14 is provided on the central axis of the piston rod 1, and the axial center hole 14 passes through the piston rod 1. When the piston rod 1 is working, the oil in the bushing 3 can flow through the axial center hole 14 to the end surface of the first end 11 of the piston rod 1 to lubricate the piston rod 1 and the sliding shoe 2.

[0045] As a preferred technical solution of this embodiment, the mounting hole 13 on the piston rod extends radially and passes through the piston rod 1 , and the mounting hole 13 is vertically connected to the axial center hole 14 .

[0046] As a preferred technical solution of this embodiment, in order to ensure that when the piston rod 1 slides to the minimum angle in the bushing 3, it still does not affect the circulation of oil in the axial center hole 14, an oil guide groove 15 is provided on the end face of the second end 12 of the piston rod 1, and one end of the oil guide groove 15 is connected to the axial center hole 14, and the other end of the oil guide groove 15 extends to the circumferential surface of the piston rod 1.

[0047] As a preferred technical solution of this embodiment, in order to facilitate the assembly of the retaining ring 6 , an annular groove 16 is further formed on the outer peripheral surface of the piston rod 1 .

[0048] One end of the sliding shoe 2 is a plane end face, and the plane end face of the sliding shoe 2 is in contact with the end face of the first end 11 of the piston rod 1, and the other end of the sliding shoe 2 forms a spherical cavity, which cooperates with the swash plate 9. The swash plate 9 is provided with a ball head 91, which extends into the spherical cavity of the sliding shoe 2 and is movably assembled with the sliding shoe 2.

[0049] The piston rod 1 is also provided with a guide sleeve 4 and an elastic member 5. The guide sleeve 4 is sleeved on the piston rod 1. A retaining ring 6 is installed in the annular groove 16 of the piston rod 1. The guide sleeve 4 is located between the first end 11 of the piston rod 1 and the retaining ring 6. During pre-assembly, the retaining ring 6 can limit the position of the guide sleeve 4 on the piston rod 1. The elastic member 5 is sleeved on the piston rod 1. The elastic member 5 is located between the first end 11 of the piston rod 1 and the guide sleeve 4. The two ends of the elastic member 5 respectively abut against the first end 11 of the piston rod 1 and the guide sleeve 4. The elastic member 5 can be selected but not limited to a spring.

[0050] The present embodiment further provides a variable piston machine, comprising a housing 7, a rotary cylinder 8, a swash plate 9, the aforementioned piston mechanism and a variable piston 10. The rotary cylinder 8, the swash plate 9, the aforementioned piston mechanism and the variable piston 10 are all arranged in the housing 7. The rotary cylinder 8 is rotatably assembled in the housing 7. The swash plate 9 can be swung in the housing 7. The swash plate 9 controls the displacement of the rotary cylinder 8. The piston mechanism and the variable piston 10 are located on the outer periphery of the rotary cylinder 8. The piston mechanism and the variable piston 10 are relatively arranged to cooperate with each other to control the inclination angle of the swash plate 9.

[0051] like Figure 4-5 As shown, the piston mechanism of the variable piston machine of this embodiment, when in use, when the piston rod 1 pushes the swash plate 9 to move to the maximum angle β, the axis of the slipper 2 and the axis of the piston rod 1 are almost coaxial, specifically, the offset distance D1 of the axis of the slipper 2 relative to the axis of the piston rod 1 is not greater than 2 mm.

[0052]

[0053] Wherein, D2 is the distance from the central axis of the piston rod 1 to the rotation axis of the variable piston machine, and the central axis of the piston rod 1 is parallel to the rotation axis of the variable piston machine; a is the distance from the center of the ball head 91 on the swash plate 9 to the center line of the swash plate 9; b is the distance from the center plane of rotation to the center of the ball head 91. Through the above relationship, the value of D1 can be limited to be set to no more than 2mm to reduce the contact forces F1 and F2 generated by the moment Ma=Fa*D1 on the piston rod 1, Fa is the force generated by the swash plate 9 on the first end 11 of the piston rod 1 through the sliding shoe 2, F1 is the contact force generated between the piston rod 1 and the guide sleeve 6, and F2 is the contact force generated between the piston rod 1 and the bushing 3.

[0054] In order to ensure the force balance of the piston rod 1, the axial direction must meet

[0055] Fa=Fb

[0056] In the direction perpendicular to the axial direction,

[0057] F1=F2

[0058] Wherein, Fb is the force exerted by the pressure oil on the second end 12 of the piston rod 1 .

[0059] In order to ensure the torque balance on the piston rod 1, the following conditions must be met:

[0060] Fa*D1=F2*X2-F1*X1

[0061] Since F1=F2, it can be deduced that:

[0062] Fa*D1=F1*(X2-X1)

[0063] X1 is the distance from the end face of the first end 11 of the piston rod 1 to the axial midpoint of the guide sleeve 4 when the swash plate 9 is at the maximum angle; X2 is the distance from the end face of the first end 11 of the piston rod 1 to the axial midpoint of the part of the bushing 3 in contact with the piston rod 1 when the swash plate 9 is at the maximum angle. When the swash plate 9 is at the maximum angle, Fa*D1 is a constant. To achieve the minimum F1, the larger X2-X1 is, the more favorable it is. When designing a variable piston machine, X2 is positively correlated with the overall length of the variable piston machine, that is, the larger X2 is, the longer the length of the variable piston machine is, which leads to the installation space limitation of the variable piston machine in the application end equipment. Therefore, X2 is limited by the overall length of the piston machine. After the length of X2 is determined, the smaller X1 is, the larger (X2-X1), that is, the more favorable it is. Since X2 is divided into two ends, X1 and (X2-X1), the basic requirement X2-X1>X1 is met, that is, X1 / (X2-X1)<1.

[0064] When the swash plate 9 moves to the zero position, the inclination angle of the swash plate 9 is 0. At this time, the end face of the second end 12 of the piston rod 1 is close to the end port of the bushing 3 away from the sliding shoe 2, that is, close to the inner bottom surface of the pressure chamber formed by the inner wall of the bushing 3 and the outer shell 7, which can limit the inertial movement of the piston rod 1 and prevent the swash plate 9 from tilting to a negative swing angle; in addition, under the action of the oil guide groove 15, the pressure oil can quickly enter the pressure chamber again to adjust the angle of the swash plate 9.

[0065] The embodiments of the present invention are described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge scope of ordinary technicians in this field without departing from the purpose of the present invention.

Claims

1. A piston mechanism for a variable displacement piston machine, characterized in that: include: A piston rod (1), wherein a first end (11) of the piston rod (1) is formed with an annular protrusion extending along the end surface, a second end (12) of the piston rod (1) is columnar, and a mounting hole (13) is formed on the piston rod (1); A sliding shoe (2), wherein a plane of the sliding shoe (2) is in contact with an end surface of a first end (11) of the piston rod (1), and the piston rod (1) acts on a swash plate (9) via the sliding shoe (2); The second end (12) of the piston rod (1) extends into the bushing (3) to slide, and the piston rod (1) is in surface contact with the bushing (3).

2. A piston mechanism for a variable displacement piston machine according to claim 1, characterized in that: A ball head (91) is formed on the inclined plate (9), and the ball head (91) extends into the sliding shoe (2) for active engagement.

3. A piston mechanism for a variable displacement piston machine according to claim 1, characterized in that: When the piston rod (1) pushes the swash plate (9) to move to a maximum angle, the offset distance of the axis of the sliding shoe (2) relative to the axis of the piston rod (1) is D1, and D1 is not greater than 2 mm.

4. A piston mechanism for a variable displacement piston machine according to claim 1, characterized in that: When the swash plate (9) is at zero position, the end surface of the second end (12) of the piston rod (1) is close to the end port of the bushing (3) away from the sliding shoe (2).

5. A piston mechanism for a variable displacement piston machine according to any one of claims 1 to 4, characterized in that: The piston rod (1) is formed with a penetrating axial center hole (14), and the axial center hole (14) is vertically connected to the mounting hole (13).

6. A piston mechanism for a variable displacement piston machine according to claim 5, characterized in that: An oil guide groove (15) is formed on the end surface of the second end (12) of the piston rod (1), and the oil guide groove (15) is in communication with the axial center hole (14).

7. The piston mechanism for a variable displacement piston machine according to claim 1, characterized in that: The piston rod (1) is sleeved with a guide sleeve (4) and an elastic member (5), and the elastic member (5) is located between the guide sleeve (4) and the first end (11) of the piston rod (1).

8. The piston mechanism for a variable displacement piston machine according to claim 7, characterized in that: The piston rod (1) is also sleeved with a retaining ring (6), the retaining ring (6) being located on a side of the guide sleeve (4) away from the elastic member (5), and the retaining ring (6) can limit the position of the guide sleeve (4) on the piston rod (1).

9. A piston mechanism for a variable displacement piston machine according to any one of claims 7 to 8, characterized in that: When the swash plate (9) moves to a maximum angle, the distance from the end surface of the first end (11) of the piston rod (1) to the guide sleeve (4) is X1, and the distance from the end surface of the first end (11) of the piston rod (1) to the axial midpoint of the contact portion between the piston rod (1) and the bushing (3) is X2, and X1 / (X2-X1)<1.

10. A variable displacement piston machine, characterized in that: include: Housing (7), A rotary cylinder (8), the rotary cylinder (8) being rotatably mounted in the housing (7); a swash plate (9), the swash plate (9) being mounted in the housing (7) in a swingable manner and controlling the displacement of the rotary cylinder (8); The piston mechanism according to any one of claims 1 to 9; A variable piston (10), the variable piston (10) being arranged opposite to the piston mechanism and cooperating to control the inclination angle of the swash plate (9).

Images