CN113483140A

CN113483140A - Hydraulic actuator

Info

Publication number: CN113483140A
Application number: CN202110829501.0A
Authority: CN
Inventors: 徐云龙; 郑飞翔; 刘晓娜; 时岩; 黄海涛
Original assignee: Schaeffler Technologies AG and Co KG
Current assignee: Schaeffler Technologies AG and Co KG
Priority date: 2021-07-22
Filing date: 2021-07-22
Publication date: 2021-10-08

Abstract

The present invention relates to a hydraulic actuator. The hydraulic actuator includes a housing having an internal cavity and a plurality of ports communicating the internal cavity with different hydraulic flow passages, respectively, and a control valve mounted in the internal cavity and including a spool movable relative to the internal cavity to close one or more of the plurality of ports. Wherein the control valve further comprises a hollow cage fixed in the inner cavity, an inner wall of the cage defining at least a part of the working chamber for the spool and guiding the spool to move along the working chamber, the cage having a plurality of through openings corresponding to the plurality of ports, respectively, such that the plurality of ports directly communicate with the working chamber via the corresponding through openings, respectively. The hydraulic actuator of the invention has simple structure and small flow resistance.

Description

Hydraulic actuator

Technical Field

The invention relates to the technical field of hydraulic control. In particular, the present invention relates to a hydraulic actuator.

Background

Hydraulic actuators are common actuation mechanisms in mechanical devices. A hydraulic chamber and a flow passage are formed in a housing of the hydraulic actuator, and the flow of hydraulic fluid in the hydraulic chamber and the flow passage can be controlled by a control valve installed in the housing, thereby performing an actuating function by hydraulic pressure. Hydraulic actuators are widely used. For example, hydraulic actuators are often employed in motor vehicles to control parking lock mechanisms in order to actuate mechanical parking lock mechanisms to lock or unlock the drive system and wheels when the vehicle is parked on a roadway.

The hydraulic actuator controls the supply of hydraulic fluid by means of a control valve. In existing control valve designs, a separate valve body is provided in the control valve. The valve body accommodates other components such as a spool and a retainer of the control valve in a cavity thereof. The cage guides the valve spool to slide axially in the valve body and positions the valve spool radially relative to the valve body. For example, CN 106471226 a discloses an oil pump control valve, in which a sleeve-type retainer fixed inside a valve body is provided, a working space for axial sliding of a ball valve core is formed in the retainer, and the positioning of the ball valve core in the radial direction is realized by the retainer. However, due to the presence of an additional housing such as a valve body, the hydraulic fluid experiences significant resistance as it passes through the various housing and flow passage structures. At the same time, a seal is required to prevent leakage of hydraulic fluid from the gap between the flow passage in the valve body and the flow passage in the actuator housing.

Disclosure of Invention

Accordingly, the present invention is directed to an improved hydraulic actuator.

The above technical problem is solved by a hydraulic actuator according to the present invention. The hydraulic actuator includes a housing having an internal cavity and a plurality of ports communicating the internal cavity with different hydraulic flow passages, respectively, and a control valve mounted in the internal cavity and including a spool movable relative to the internal cavity to close one or more of the plurality of ports. The control valve further comprises a hollow retainer, the retainer is directly abutted against the inner wall of the inner cavity, so that the retainer is fixed in the inner cavity, at least one part of the working cavity for the valve core is limited by the inner wall of the retainer and the valve core is guided to move along the working cavity, the retainer is provided with a plurality of through openings corresponding to the plurality of ports respectively, and the plurality of ports are directly communicated with the working cavity through the corresponding through openings respectively. The working chamber accommodating the valve spool communicates with the port in the housing only through the through opening in the retainer, which means that the valve body housing for accommodating the retainer and the valve spool in the conventional control valve is omitted. Therefore, the structure of the whole hydraulic actuator is obviously simplified, and the interfaces between different structures through which hydraulic fluid flowing between the working chamber and the ports needs to pass are fewer, so that the flow of the hydraulic fluid is smoother, the response speed of the control valve is higher, and the operation is more stable during switching.

According to a preferred embodiment of the present invention, the plurality of ports may include first and second ports axially opposite at both ends of the inner cavity and a third port located on a sidewall of the inner cavity, and the spool is axially movable in the inner cavity to close the first or second port. For example, the lumen may be generally formed in a generally cylindrical shape. The first and second ports may be ports for inflow and outflow of hydraulic fluid, respectively, and the third port may be a port communicating with a hydraulic working chamber for performing a function of the hydraulic actuator.

According to another preferred embodiment of the invention, the cage may have a first end facing the first port and a second end facing the second port, and the first end and/or the second end may be open ends constituting through openings corresponding to the first port and/or the second port.

According to a further preferred embodiment of the invention, the cage may have a radially through-going window in the side wall region corresponding to the third port, the window constituting a through-going opening corresponding to the third port.

According to a further preferred embodiment of the invention, the cage may have a first section in the axial direction adjacent to the first port, by which the cage may be fixed in the inner cavity, and a second section adjacent to the second port, in which the window is formed. In this case, the outer wall of the first section may be in sealing contact with the inner wall of the lumen, and there may be a gap between the outer wall of the second section and the inner wall of the lumen.

According to another preferred embodiment of the invention, the control valve may be mounted into the inner cavity from the first port, the spool cooperating with the through opening of the cage to close the first port.

According to another preferred embodiment of the invention, the valve core may be a ball valve core. The radial position of the ball valve element relative to the bore is defined by the inner wall of the cage. In other embodiments, the valve core may be a cylindrical or other type of valve core.

According to another preferred embodiment of the present invention, the housing and the holder may be respectively formed of a plastic material. In this case, the cage can be fixedly connected to the housing by ultrasonic welding. This allows the materials of the contact portions of the housing and the holder to be completely joined together, thereby providing stable structural strength and good sealing effect. Alternatively, the housing and the holder may also be formed from a metallic material, and the holder may be fixedly connected to the housing by laser welding or press fitting.

Drawings

The invention is further described below with reference to the accompanying drawings. Identical reference numbers in the figures denote functionally identical elements. Wherein:

fig. 1a and 1b show longitudinal cross-sectional views of a hydraulic actuator according to an embodiment of the invention, respectively;

FIG. 2 illustrates a perspective view of a cage of a hydraulic actuator according to an embodiment of the present invention; and

fig. 3 shows a transverse cross-sectional view of a hydraulic actuator according to an embodiment of the invention.

Detailed Description

Hereinafter, a specific embodiment of the hydraulic actuator according to the present invention will be described with reference to the accompanying drawings. The following detailed description and drawings are included to illustrate the principles of the invention, which is not to be limited to the preferred embodiments described, but is to be defined by the appended claims.

According to an embodiment of the present invention, a hydraulic actuator is provided. Such hydraulic actuators operate by hydraulic fluid for actuating other mechanical mechanisms and the like. For example, such a hydraulic actuator may be used to control a parking lock mechanism of a motor vehicle.

Fig. 1a and 1b show an exemplary embodiment of a hydraulic actuator according to the present invention. As shown, the hydraulic actuator is shown as a parking lock mechanism actuator, which includes a housing 10, a control valve 20, and an actuating mechanism 30. The housing 10 has a hollow interior 11. The housing 10 also has a plurality of ports provided on the inner wall of the inner chamber 11 so as to communicate the inner chamber 11 with different hydraulic flow passages inside or outside the housing 10, respectively.

A control valve 20 is mounted in the inner chamber 11. The control valve 20 includes a cage 21 and a spool 22. Unlike the control valve of the conventional hydraulic actuator, the control valve 20 according to the present invention does not have a valve body for accommodating the retainer and the spool, and the retainer 21 is directly installed in the inner chamber 11. The holder 21 has a hollow structure. The outer wall of the cage 21 directly abuts the inner wall of the cavity 11 so that the cage 21 is fixed in the cavity 11.

The spool 22 is slidably mounted in the cage 21. The inner wall of the cage 21 defines part or all of a working chamber for the spool 22. While the inner wall 21 of the cage 21 defines only a portion of the working chamber for the spool 22, another portion of the working chamber may be defined by an inner wall (e.g., an end face) of the internal cavity 11. The inner wall of the cage 21 can guide the spool 22 to move along the working chamber. One or more of the plurality of ports can be closed by spool 22 moving to a corresponding position. To facilitate sealing of the ports on the end faces, the cartridge 22 may be a spherical cartridge as shown. However, a cylindrical or other shaped valve cartridge may be used as desired.

The actuating mechanism 30 is mounted on the housing 10. The actuating mechanism 30 comprises a push rod 31. The push rod 31 extends through the housing 10 into the inner cavity 11. The end of the push rod 31 extending into the inner cavity 11 is fixedly connected with the valve core 22, and when the actuating mechanism 30 operates the push rod 31 to perform telescopic motion, the push rod 31 drives the valve core 22 to move along the working cavity. In the present embodiment, the actuation mechanism 30 is an electromagnetic actuation mechanism, but in other embodiments, the actuation mechanism 30 may be other types of actuation mechanisms.

The holder 21 has a plurality of through openings which correspond to a plurality of ports in the housing 10, respectively. Each port in the housing 10 communicates directly with a working chamber in the cage 21 via a corresponding through opening, respectively, i.e. the hydraulic fluid flowing between the port and the working chamber need not pass through other physical structures than the through opening in the cage 21.

In the particular embodiment shown in fig. 1a and 1b, the inner cavity 11 is formed as a substantially cylindrical cavity, with the first port P and the second port T being formed at axially opposite ends of the inner cavity 11, respectively, and the third port a being formed on a sidewall of the inner cavity 11. The first port P is, for example, an inflow port (also commonly referred to as a port P) of hydraulic fluid, the second port T is, for example, an outflow port (also commonly referred to as a port T) of hydraulic fluid, and the third port a is, for example, a port (also commonly referred to as a port a) communicating with a hydraulic working chamber that performs a function of a hydraulic actuator.

Fig. 2 shows a perspective view of the cage 21. As shown in fig. 2, the cage 21 is also formed in a generally cylindrical structure having axially opposite first and second ends, respectively. Both ends of the holder 21 are open ends. When the cage 21 is mounted in the internal cavity 11, the first end faces the first port P, thus constituting a through opening corresponding to the first port P; the second end faces the second port T, thereby constituting a through opening corresponding to the second port T. The pushrod 31 may extend into the working chamber through the first port P or the second port T to connect the spool 22 in the working chamber.

The open bore diameter of the second end of the cage 21 may be larger than the outer diameter of the spool 22, so that the spool 22 may directly contact the end surface of the inner cavity 11 to close the second port T when moving to the second end (as shown in fig. 1 a). A step toward the second end may be formed at the inside of the spool 22, and the inner diameter of the step is smaller than the outer diameter of the spool 22, so that the spool 22 may abut the step to close the first port P when moving to the step (as shown in fig. 1 b). The control valve 20 is installed from the first port P into the inner cavity 11, and in this case, the inner diameter of the first port P is necessarily larger than the outer diameter of the spool 22. Therefore, it is necessary to close the first port P by the step in the cage 21 to cooperate with the spool 22 and restrict the axial movement of the spool 22. In this configuration, the working chamber for the spool 22 is defined collectively by the inner side wall of the retainer 21, the step, and the end face of the inner chamber 11.

As shown in the transverse cross-sectional view of fig. 3, one or more radially penetrating windows 23 may be formed in the sidewall of the holder 21 so as to constitute a penetrating opening corresponding to the third port a. In this case, the window 23 is formed in the axial region between the step and the second end. For example, the windows 23 may be formed as open slots extending axially from the sidewall to the second end of the cage 21, and a plurality of such windows 23 may be circumferentially spaced apart. Preferably, the axial extension of the window 23 covers at least the axial extension of the third port a.

The cage 21 may include a first section 211 adjacent to the first port P and a second section 212 adjacent to the second port T in the axial direction. Wherein, the outer diameter of the first section 211 is larger than the outer diameter of the second section 212, so that the outer wall of the first section 211 abuts against the inner wall of the inner cavity 11, thereby fixing the holder 21 in the inner cavity 11 through the first section 211, and there is no fitting relation between the outer wall of the second section 212 and the inner wall of the inner cavity 11, so that there may be a certain gap. The window 23 is formed in the second section 212. In order to allow the working chamber and the port P to communicate with each other only through the open first end, it is necessary to ensure sealability between the outer wall of the first end and the inner wall of the inner chamber 11. Thus, the outer wall of the first section 211 is in sealing contact with the inner wall of the inner cavity 11. A cylindrical step facing the second port T is formed between the first section 211 and the second section 212 of the cage 21 due to the difference in diameter, while a cylindrical step facing the first port P is also formed in the inner cavity 11 of the housing 10 accordingly. When the cage 21 is mounted in place in the cavity 11, the steps of the two axially abut each other.

In an exemplary embodiment of the present invention, both the housing 10 and the holder 21 may be made of a plastic material. In this case, the holder 21 may be fixed in the cavity 11 by ultrasonic welding in order to achieve a sealing contact therebetween. The plastic material of the outer wall of the first section 211 and the inner wall of the inner cavity 11 (comprising mutually abutting step surfaces) may be integrally connected by ultrasonic welding. The contact surfaces in the first section 211 and the step produce a weld interface fusion bond when ultrasonic welding is performed, at which time the molten material can be accommodated in the gap between the second section 212 and the cavity 11. In the prior art, because the valve body is usually made of metal materials and can only be fixed in a compression fit mode, the structural strength and the sealing effect are not ideal. In contrast, ultrasonic welding results in a significant increase in both the structural strength and the sealing effect of the joint.

In an alternative embodiment of the present invention, the housing 10 and the holder 21 may both be made of a metal material, similar to the prior art. In this case, the holder 21 may be fixedly coupled to the housing 10 by laser welding or press fitting.

The hydraulic actuator of the present invention is intended to achieve the function of a complete control valve by the cooperation of the retainer 21, the spool 22 and the housing 10, thereby omitting the valve body housing structure of the prior art. In such a hydraulic actuator, the fluid communication between the working chambers for the spool 22 and the ports in the housing 10 is achieved directly through the through openings in the cage 21 and no longer through the openings in the valve body housing. This not only makes the structure of the hydraulic actuator simpler, but also can reduce the fluid resistance that the hydraulic fluid produces when passing through the interface between different structures, so that the performance of the hydraulic actuator can be improved. Under such a concept, specific structures of the housing 10 and the holder 21, and structures and numbers of the inner cavities, the flow passages, and the ports, etc., may be variously changed, not limited to the forms described in the above embodiments.

Although possible embodiments have been described by way of example in the above description, it should be understood that numerous embodiment variations exist, still by way of combination of all technical features and embodiments that are known and that are obvious to a person skilled in the art. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration of the invention in any way. From the foregoing description, one of ordinary skill in the art will more particularly provide a technical guide to convert at least one exemplary embodiment, wherein various changes may be made, particularly in matters of function and structure of the components described, without departing from the scope of the following claims.

List of reference numerals

10 casing

11 inner cavity

20 control valve

21 holder

211 first section

212 second section

22 spool

23 Window

30 actuating mechanism

31 push rod

P first port

T second port

A third port

Claims

1. A hydraulic actuator comprising a housing (10) and a control valve (20), the housing (10) having an internal chamber (11) and a plurality of ports communicating the internal chamber (11) with different hydraulic flow passages respectively, the control valve (20) being mounted in the internal chamber (11) and comprising a spool (22), the spool (22) being movable relative to the internal chamber (11) to close one or more of the plurality of ports,

it is characterized in that the preparation method is characterized in that,

the control valve (20) further comprises a hollow cage (21), the cage (21) being fixed in the inner chamber (11), an inner wall of the cage (21) defining at least a part of a working chamber for the spool (22) and guiding the spool (22) to move along the working chamber, the cage (21) having a plurality of through openings corresponding to the plurality of ports, respectively, such that the plurality of ports directly communicate with the working chamber via the corresponding through openings, respectively.

2. The hydraulic actuator according to claim 1, wherein the plurality of ports includes a first port (P) and a second port (T) axially opposed at both ends of the internal cavity (11) and a third port (a) located on a side wall of the internal cavity (11), the spool (22) being axially movable in the internal cavity (11) to close the first port (P) or the second port (T).

3. The hydraulic actuator according to claim 2, characterized in that the cage (21) has a first end facing the first port (P) and a second end facing the second port (T), the first end and/or the second end being open ends constituting through openings corresponding to the first port (P) and/or the second port (T).

4. The hydraulic actuator according to claim 3, characterized in that the cage (21) has a window (23) passing through in a radial direction in a side wall region corresponding to the third port (A), the window (23) constituting a through opening corresponding to the third port (A).

5. Hydraulic actuator according to claim 4, characterized in that the cage (21) has in axial direction a first section close to the first port (P) by which the cage (21) is fixed in the inner cavity (11) and a second section close to the second port (T) in which the window (23) is formed.

6. Hydraulic actuator according to claim 5, characterized in that the outer wall of the first section is in sealing contact with the inner wall of the inner cavity (11) and that there is a gap between the outer wall of the second section and the inner wall of the inner cavity (11).

7. The hydraulic actuator according to claim 5, characterized in that the control valve (20) is installed into the internal cavity (11) from the first port (P), the spool (22) cooperating with a through opening of the cage (21) to close the first port (P).

8. The hydraulic actuator of claim 1, wherein the spool (22) is a spherical spool.

9. The hydraulic actuator according to any one of claims 1 to 8, characterized in that the housing (10) and the cage (21) are each formed from a plastic material, the cage (21) being fixedly connected to the housing (10) by ultrasonic welding.

10. The hydraulic actuator according to any one of claims 1 to 8, characterized in that the housing (10) and the retainer (21) are formed of a metal material, and the retainer (21) is fixedly connected to the housing (10) by laser welding or press fitting.