JP2002257252A - Actuator assembly for hydraulic system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an actuator assembly for a piezoelectric(PZT) type hydraulic valve. SOLUTION: The actuator assembly for a hydraulic system is connected via a fluid source with fluid, and has the hydraulic valve, having a valve spool for adjusting flow of the fluid flowing to an actuator through the valve spool. The actuator assembly further has a piezoelectric actuator connected to the hydraulic valve, so as to move the hydraulic valve in response to a signal to the piezoelectric actuator.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates generally to valves, and more particularly, to actuator assemblies for automotive hydraulic systems.

[0002]

[Description of the Related Art A vehicle such as an automobile, at work machine, machine tool or many other systems utilized in various application fields, it is known to use a hydraulic valve. Typically, in the automotive, hydraulic valve it is an anti-lock braking system (ABS) and, in a traction control system (TCS), are most commonly used to adjust the brake cylinder pressure.

[0003] Further, the brake-by-wire (BBW) techniques are also known that currently being developed by the automotive manufacturer. One such BBW technique is electro-hydraulic braking, which also requires a group of valves to achieve the required braking. In work machines, valves are used to move linkages and tools to required positions through hydraulic systems. The valve is driven by an electromagnetic solenoid or a pilot system. However, electronically controlled valves are all driven by electromagnetic solenoids.

While the above electromagnetic solenoids have operated, they suffer from electromagnetic interference (EMI). Another disadvantage is that the electromagnetic solenoid can only move in one direction, ie in one direction. Therefore, most dual-acting hydraulic valves require the use of two solenoids located at opposite ends of the valve spool of the hydraulic valve.

Accordingly, it is desirable to provide a hydraulic valve actuator assembly that eliminates electromagnetic interference. or,
It would also be desirable to provide an actuator assembly for a bi-directional hydraulic valve that does not require two solenoids at either end of the valve spool of the hydraulic valve. It would further be desirable to provide a lightweight actuator assembly for a hydraulic valve that operates over a wider temperature range without hysteresis. Accordingly, there is a need in the art to provide an actuator assembly for a hydraulic valve that meets these needs.

[0006]

SUMMARY OF THE INVENTION Accordingly, the present invention is an actuator assembly for a hydraulic system, wherein the valve spool is fluidly connected to a fluid source and regulates fluid flow through the valve spool to the actuator. With a hydraulic valve having The actuator assembly also has a piezoelectric actuator connected to the hydraulic valve to move the hydraulic valve in response to a signal to the hydraulic valve.

[0007] One advantage of the present invention is that the actuator assembly for a piezoelectric (PZT) type hydraulic valve is provided. Another advantage of the present invention, the actuator assembly to operate the valve spool of the hydraulic valve, without requiring the use of an electromagnetic solenoid is to use a PZT actuator. Yet another advantage of the present invention is that to move the valve spool in both directions, the actuator assembly can easily achieve bidirectional operation, requiring only one PZT actuator for a dual acting hydraulic valve. That is. Yet another advantage of the present invention, the actuator assembly has a large holding force, as a result, if the spring is no, or the size of the spring is reduced. Yet another advantage of the present invention is that the actuator assembly eliminates electromagnetic interference, reduces the number of components, and reduces cost. Yet another advantage of the present invention, according to the actuator assembly, the positioning accuracy of the valve is increased,
It has less hysteresis, operates over a wider temperature range, and is lighter (higher density force).

[0008] Other features and advantages of the present invention will become better understood and apparent from a reading of the detailed description of the invention with reference to the accompanying drawings.

[0009]

[Preferred embodiments of the description the drawings, particularly to FIG. 1, the actuator assembly 10 according to the present invention is shown in a state which cooperates with a hydraulic system, generally indicated at 12. Hydraulic system 12 includes a tank 14 containing hydraulic fluid and a pump 16 fluidly connected to tank 14 by any suitable means, such as a pipe or hose 17. The actuator assembly 10 by suitable means such as a tube or hose 17, pump 1
6 and an actuator 18 such as a caliper (not shown) of a brake system (not shown). Hydraulic system 12 also includes a motor 20 that is connected to pump 16 by any suitable means, such as a coupling (not shown), for driving pump 16. Hydraulic system 1
2 further includes an electronic controller 22 electrically connected to the motor 20 and the actuator assembly 10 by suitable means such as a wire 24 to supply power and control the motor 20 and the actuator assembly 10. Have. The actuator assembly 10 includes a pump 16 and an actuator 18.
It is understood to control the flow of hydraulic fluid to the It is also understood that, apart from the actuator assembly 10, the hydraulic system 12 is conventional and known.

As shown in FIGS. 1 and 2, the actuator assembly valve 10 according to the present invention has a hydraulic valve 25 for controlling the flow of hydraulic fluid. Hydraulic valve 25 has a housing or manifold block 26, which has a fluid chamber 28 therein, which is connected to hose 17. Although the housing 26 as shown is substantially cylindrical, other suitable structures may be used. The housing 26 has one opening 30 extending through its opposite ends in the longitudinal direction. The housing 26 is made of a metal material such as aluminum.
Housing 26 is an assembly of individual components including a hydraulic seal (not shown).

[0011] liquid valve 25 further comprises a valve spool 32 can move therein is disposed within the fluid chamber 28 of the housing 26. The valve spool 32 has a shaft portion 34 that extends axially and through the openings 30 in the housing 26. The shaft portion 34 has a substantially columnar shape and a substantially circular cross section. The valve spool 32 further has a plurality (preferably two) of disk portions 36. The disk portions 36 extend radially from the shaft portion 34 and are spaced apart in the axial direction. The function of the disk unit 36 will be described later. Disk portion 36 is substantially circular. The valve spool 32 is made of a metal material such as aluminum. The valve spool 32 has a single structure and is an integral body. The hydraulic valve 25 may be understood as a conventionally known one.

[0012] The actuator assembly 10 further includes a piezoelectric actuator 38 connected to the hydraulic valve 25. This is for moving the valve spool 32 in the hydraulic valve 25. The piezoelectric actuator 38 includes a chamber 42
Having a housing 40 having As shown, housing 40 has a generally cylindrical shape, but other suitable structures may be used. The housing 40 has one opening 44 extending longitudinally through both ends. Housing 40
Is made of a metal material such as aluminum. The housing 40 is an assembly comprising a plurality of components.

The piezoelectric actuator 38 further has a core spool 46. The core spool 46 is connected to the housing 40.
And is movable within it. The core spool 46 has an axially extending shaft portion 48 and reduced diameter end portions 50 extending axially from the shaft portion 48 through the opening 44 of the housing 40. One of the end portions 50 is connected to the valve spool 32 of the hydraulic valve 25 by any suitable means such as a mechanical fastener (not shown). The shaft portion 48 has a substantially columnar shape and a substantially circular cross section. The core spool 46 is made of a metal material such as steel.

The piezoelectric actuator 38 further has at least one, preferably a plurality, preferably six, piezoelectric motors 52. The piezoelectric motors 52 extend radially from the core spool 46 and are spaced apart in the axial direction. The function will be described later. Piezoelectric motor 5
2 is almost rectangular. The piezoelectric motor 52 is a linear motor is disclosed in U.S. Patent No. 5,453,653 of Zumerisu (Zumeris). The disclosure of that patent is hereby incorporated by reference. The piezo motor 52 is based on a piezo plate, which excites it to a transverse bending vibration mode in the vicinity of a longitudinally extending mode under an excitation drive and ceramic shape. . The piezoelectric motor 52 is connected to the controller 22 by a suitable means such as an electric wire. The piezoelectric actuator 38 further includes at least one disposed between the motor 52 and the housing 40 in the chamber 42 preferably has a plurality of support springs 54. Spring 54, by suitable means, is connected to the piezoelectric motor 52 and housing 40. It should be recognized that the piezoelectric motor 52 has a wide range of movement and is not subject to electromagnetic interference. or,
It should also be appreciated that the piezoelectric motor 52 exhibits an intrinsic stopping force (stalling force) when no electric field is applied. It should further be appreciated that the piezoelectric motor 52 is known.

The actuator assembly 10 may include at least one repositioning spring 56. Relocation spring 56
Is near the end of the shaft portion 34 is disposed between the housing 26 and the holding member 58. The holding member 58
Extending radially from the shaft portion 34, by suitable means such as mechanical fasteners (not shown) is connected to the shaft portion 34. The rearrangement spring 56 is a coil spring. Relocation spring 56, when the piezoelectric actuator 38 is not driven, the valve spool 32 is returned to the predetermined position. It should be recognized that repositioning spring 56 is present even when precise control of actuator position is not being performed. It should also be appreciated that if position feedback is available or if the accuracy of the position of the valve spool 32 is not a concern, the repositioning spring 56 may be omitted as shown in FIG.

In operation of actuator assembly 10, controller 22 issues a command to piezoelectric actuator 38 to allow hydraulic fluid, such as oil, to flow through hydraulic valve 25. Power from controller 22 is received by piezo motor 52, which provides drive frequency to core spool 46. Since the piezoelectric motor 52 is coupled to the core spool 46, an asymmetric driving force is applied to the core spool 46 to cause movement. The driving force periodicity of a frequency much higher than the mechanical resonance frequency of the core spool 46, a continuous smooth motion for unlimited movement is allowed. In addition, high resolution and positioning accuracy are maintained. The linear movement of the core spool 46 in turn causes the valve spool 32 to move linearly, thereby causing the actuator 1 to move from the pump 16 through the hydraulic valve 25.
Is hydraulic fluid flow to 8 are controlled tuned. Hydraulic valve 2
5, it should be recognized that a single operation valve with a single operation valve spool 32 which is driven by a linear piezoelectric actuator 38.

FIG. 4 shows another embodiment 110 of the actuator assembly 10 of the present invention. An actuator assembly 10 components similar parts are denoted by the numerals obtained by adding 100. In this embodiment, the actuator assembly 110 has a piezoelectric actuator 128. The piezoelectric actuator 128 is used in conjunction with both operating fluid valve 125, it is possible to make both linear direction operation. The hydraulic valve 125 has a housing 126. The housing 126 is connected to the tank 14 by a first hose 17a, and is connected to the pump 16 by a second hose 17b. The housing 126 also includes a third
The hose 17c is also connected to a rod end (RE) of a cylinder (not shown). The cylinder has a piston (not shown) and a rod (not shown) connected to the piston and extending out of the cylinder. The housing 126 is also connected to the cylinder head end (HE) by a fourth hose 17d. The valve spool 132 further extends radially to form a plurality of disk portions.
136 are spaced between the axial direction between the seal portion 1
With 60. The seal portion 160 has a groove 162 extending radially inward and circumferentially.
A seal 164 such as an O-ring disposed therein. The seal part 160 is provided with a hydraulic fluid that is a disk part (plurality) 136.
To prevent passing through.

The actuator assembly 110 may have repositioning springs 156 near both ends of the shaft portion 134 of the valve spool 132. At one end, it extends radially from the shaft portion 134 is disposed between the housing 126 and the holding member 158, at the other end, is disposed between the coupling portion 166 and the housing 126. Retaining member 158 extends radially from shaft portion 134 and is connected to one end of shaft portion 134 by any suitable means, such as a mechanical fastener (not shown). The connecting portion 166 is connected to the valve spool 1
32 and both ends 134 and 150 of the core spool 146. The rearrangement spring 156 is a coil spring. The repositioning spring 156 causes the valve spool 13 to move when the piezoelectric actuator 138 is not driven.
2, back to the predetermined position. Relocation spring 156
It should be recognized that is present even when precise control of the actuator position is not being made. Also, either when the position feedback is available, if the accuracy of the position of the valve spool 132 is not an issue, it should be recognized that it may be omitted relocation spring 156 as shown in FIG.

In operation of actuator assembly 110, controller 22 issues a command to piezoelectric actuator 138 to allow hydraulic fluid, such as oil, to flow through hydraulic valve 125. The power from the controller 22 is applied to the piezoelectric motor 152.
And its power places the core spool 146 in drive frequency. The piezoelectric motor 152 is coupled to the core spool 146, the core spool 14
Asymmetrical driving force is applied to 6 to cause movement. The periodicity of the driving force at a frequency much higher than the mechanical resonance frequency of the core spool 146 allows continuous smooth movement for unlimited movement. In addition, high resolution and positioning accuracy are maintained. Core spool 146
Linear movement of the valve spool 132 in this case causes the valve spool 132 to move linearly in either direction, thereby controlling the flow of hydraulic fluid through the hydraulic valve 125 between the pump 16, tank 14 and actuator 18. to be adjusted.
It should be appreciated that the hydraulic valve 125 is a two-acting valve having a two-acting valve spool 132 driven by a linear piezoelectric actuator 138.

[0020] The present invention has been described above. It is to be understood that the words used herein are intended to be illustrative and not limiting.

Various modifications and variations of the present invention are possible in light of the above teachings. Therefore, within the scope of the claims, the present invention can be carried out in a mode different from that specifically described.

[Brief description of the drawings]

FIG. 1 is a block diagram of an actuator assembly according to the present invention in cooperation with a hydraulic system.

2 is a actuator assembly and cutaway elevation part of a single operation fluid valve of the hydraulic system of FIG.

Figure 3 is a similar view to Figure 2 of the absence relocation spring.

[Figure 4] of the actuator assembly and the secondary operating fluid valve of the hydraulic system of Figure 1 is an elevational view out portions cutaway of another embodiment according to the present invention.

FIG. 5 is a view similar to FIG. 2 but without a relocation spring;

────────────────────────────────────────────────── ─── of the front page continued (51) Int.Cl. ⁷ identification mark FI theme Court Bu (reference) H01L 41/08 U (72) inventor Kevin Jay Pavlov United States Michigan 48152 Li Vonia Mayfield 20123 (72) inventor Pangrock O United States 48105 Michigan Ann Arbor Green Breer Boulevard 3665 # 142 Bee F-term (Reference) DB05 DB44 DB48 EE31 GG02 GG08 HH29 JJ12 5H680 AA06 BB13 BB19 BB20 CC01 DD01 DD12 DD23 DD34 DD65 GG02

Claims (20)

[The claims] 1. A hydraulic valve fluidly connected to a fluid source and having said valve spool for regulating the flow of fluid through a valve spool to an actuator; and moving the valve spool in response to a signal to a piezoelectric actuator. And a piezoelectric actuator connected to the hydraulic valve as described above. Wherein said piezoelectric actuator includes a housing and, disposed within the housing, the actuator assembly of claim 1 having a connected core spool in the valve spool. Wherein the piezoelectric actuator, the disposed within the housing, the actuator assembly of claim 2, further comprising at least one piezoelectric motor which cooperates with the core spool to move said core spool. 4. The actuator assembly according to claim 3, wherein said piezoelectric actuator has at least one support spring connecting said at least one piezoelectric motor and said housing. 5. The actuator assembly according to claim 2, wherein said housing has an opening extending axially through both ends thereof. 6. The valve spool of claim 5, wherein the core spool has reduced diameter ends extending through the opening, one of the ends being connected to the valve spool. Actuator assembly. 7. The actuator assembly according to claim 1, wherein said hydraulic valve has a housing, and said valve spool is disposed within and movable within said housing. 8. The actuator assembly according to claim 7, wherein said housing has an opening extending axially through both ends thereof. 9. The actuator assembly according to claim 8, wherein said valve spool has opposite ends extending through said opening. 10. The actuator assembly according to claim 9, comprising at least one repositioning spring disposed near one end of said valve spool. Wherein said valve has a holding member extending radially from the one end of the spool, the actuator assembly of the relocation spring according to claim 10, wherein disposed between the holding member and the housing. 12. The actuator assembly according to claim 1, further comprising a controller electrically connected to said piezoelectric actuator to control said piezoelectric actuator to move said valve spool linearly in either direction. . 13. A hydraulic valve fluidly connected to a fluid source and having said valve spool for regulating the flow of fluid through the valve spool to the actuator; and moving the hydraulic valve in response to a signal to a piezoelectric actuator. And a piezoelectric actuator having at least one piezoelectric motor connected to the hydraulic valve. 14. The actuator assembly according to claim 13, wherein said piezoelectric actuator has a housing and a core spool disposed within said housing and connected to said valve spool. 15. The piezoelectric actuator is disposed within the housing, the actuator assembly of claim 14, wherein for cooperation with the core spool to move said core spool. 16. The actuator assembly according to claim 15, wherein the piezoelectric actuator has at least one support spring connecting the at least one piezoelectric motor and the housing. 17. The actuator assembly according to claim 16, wherein said housing has an opening extending axially through both ends thereof. 18. The core spool has both end portions having a diameter extending through said opening is reduced, according to claim 17 in which one of their ends is connected to the valve spool Actuator assembly. 19. The actuator assembly according to claim 13, comprising at least one repositioning spring disposed near one end of said valve spool. 20. A tank having an internal hydraulic fluid, an actuator for receiving the hydraulic fluid, and a pump fluidly connected to the tank from the tank to send the hydraulic fluid to the actuator , the liquid and motor connected to the pump so as to drive the pump to send the fluid, and the piezoelectric actuator assembly fluidly connected to the tank and the actuator, the hydraulic fluid through said fluid valve And a controller electrically connected to the motor and the actuator assembly to control the piezoelectric actuator assembly to allow the flow of fluid.