JP3420687B2 - Variable throttle valve - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable throttle valve having a throttle portion whose opening changes with axial displacement of a spool.

[0002]

2. Description of the Related Art For example, in a hydraulic power steering device, a variable throttle valve having a throttle portion whose opening changes according to operating conditions such as vehicle speed is used, and acts on a hydraulic actuator for generating steering assist force according to operating conditions. The hydraulic pressure is controlled.

A conventional variable throttle valve 101 shown in FIG.
A housing 102 and a spool 104 which is axially displaceably inserted into an insertion hole 103 formed in the housing 102 are provided. One peripheral edge of the first peripheral groove 103a formed on the inner periphery of the insertion hole 103 and the spool 1
The narrowed portion 105 is formed between one of the peripheral edges of the second peripheral groove 104a formed on the outer periphery of the base plate 04 and the one peripheral edge of the second peripheral groove 104a. The one peripheral edge 104a 'of the second peripheral groove 104a is the other peripheral edge 10a.
4a ", the diameter becomes smaller as it gets closer to 4a". A screw member 121 is screwed onto the spool 104. The center of the spool 104 and the center of the screw member 121 are to prevent the spool 104 from rotating. The spool 104 is displaced in the axial direction when the screw member 121 is rotationally driven by the motor 122. The axial displacement of the spool 104 causes the throttle unit 1 to be displaced.
The opening degree of 05 changes. In addition, the internal space 111 of the insertion hole 103 facing the one end surface 104b of the spool 104.
And a spring 123 for preventing rattling of the spool 104.
Is built in.

In the conventional variable throttle valve 101 described above, an inflow passage 109 for pressure oil is formed so as to be continuous with the first circumferential groove 103a. The pressure oil outflow passage 110 is formed so as to be continuous with the internal space 111 of the insertion hole 103 facing the one end surface 104b of the spool 104. The second circumferential groove 104
a is a radial hole 104e formed in the spool 104
And an internal space 111 of the insertion hole 103 facing the one end surface 104b of the spool 104 via a through hole 104f that is continuous with a female screw hole screwed to the screw member 121. Further, a fluid passage is provided in the spool 104 so as to be continuous with the internal space 111 of the insertion hole 103 facing the one end surface 104b of the spool 104 and the internal space 112 of the insertion hole 103 facing the other end surface 104c of the spool 104. 104d is formed.

According to the variable throttle valve 101, the inflow passage 1
The pressure oil that flows in from the flow path 09 flows through the first circumferential groove 103a, the narrowed portion 105, the second circumferential groove 104a, and the radial hole 104 formed in the spool 104, as indicated by the alternate long and short dash line in the figure.
e and through hole 104f, one end surface 104 of the spool 104
It flows out from the outflow passage 110 through the internal space 111 of the insertion hole 103 facing b. In addition, the internal space 11 of the insertion hole 103 facing the one end surface 104 b of the spool 104.
1 and the internal space 112 of the insertion hole 103 facing the other end surface 104c of the spool 104 communicate with the outflow passage 110 via the fluid passage 104d of the spool 104, so that the hydraulic pressure acting on the spool 104 in the axial direction is increased. Can be balanced.

[0006]

Conventional variable throttle valve 10
In No. 1, when the opening of the throttle portion 105 is small, there is a problem that an offensive sound is generated as the pressure oil flows.

Further, in the conventional variable throttle valve 101, when the pressure of the pressure oil flowing out from the outflow passage 110 suddenly fluctuates due to surging, the balance of the hydraulic pressure in the axial direction of the spool 104 is disturbed, and the spool 104 moves in the axial direction. There is a problem that the force acts and the smooth displacement of the spool 104 is hindered. Therefore, when the opening degree of the throttle portion 105 is changed according to the driving condition of the vehicle and the change in the opening degree of the throttle portion 105 controls the hydraulic pressure acting on the steering assist force generating hydraulic actuator of the hydraulic power steering device. The steering feeling is deteriorated.

An object of the present invention is to provide a variable throttle valve which can solve the above problems.

[0009]

According to the present invention, there is provided a housing and a spool which is inserted into an insertion hole formed in the housing so as to be displaceable in the axial direction. The inner circumference of the insertion hole has a first circumference. A groove is formed so as to face the outer circumference of the spool, a second circumferential groove is formed on the outer circumference of the spool, and one peripheral edge of the second circumferential groove is a taper whose diameter becomes smaller as it approaches the other peripheral edge. The surface of the first circumferential groove is between the one circumferential edge of the first circumferential groove and the one circumferential edge of the second circumferential groove, and a throttle portion for the pressure oil is formed. In the variable throttle valve that changes with the directional displacement, the first
The outflow passage of the pressure oil is formed so as to be continuous with the peripheral groove of the above, and the inflow passage of the pressure oil is formed so as to be connected to the second peripheral groove thereof. In the conventional configuration, the pressure oil flows from the first circumferential groove 103a to the second circumferential groove 104a via the throttle portion 105.
Leading to. One peripheral edge 104 of the second peripheral groove 104a
The a'is a tapered surface having a diameter that decreases as it approaches the other peripheral edge 104a ".
The flow passage area of 05 becomes larger toward the downstream side. Then, when the opening degree of the throttle portion 105 is small, the pressure of the pressure oil sharply decreases in the throttle portion 105, the amount of cavitation bubbles generated in the pressure oil increases, and the noise accompanying the flow of the pressure oil increases. become. On the other hand, according to the configuration of the present invention, the pressure oil reaches the first circumferential groove from the second circumferential groove via the throttle portion. One peripheral edge of the second peripheral groove is a tapered surface having a smaller diameter as it approaches the other peripheral edge. Therefore, the flow passage area of the narrowed portion becomes smaller toward the downstream side. Therefore, even if the opening degree of the throttle portion is small, the pressure of the pressure oil gradually decreases in the throttle portion. As a result, it is possible to suppress the generation of cavitation bubbles in the pressure oil and reduce the noise accompanying the flow of the pressure oil. In the conventional variable throttle valve 101, by making one peripheral edge of the first circumferential groove 103a formed on the inner circumference of the insertion hole 103 a tapered surface, it is possible to reduce the sound accompanying the flow of the pressure oil. Conceivable. However, in order to form the tapered surface, it is necessary to process the inner circumference of the hole, which is more difficult than the outer circumference of the spool. According to the configuration of the present invention, since the tapered surface is formed on the outer circumference of the spool, the inner circumference processing of the hole is unnecessary, so that the processing does not become difficult.

A fluid passage in the spool has an internal space of the insertion hole facing one end face of the spool, an internal space of the insertion hole facing the other end face of the spool, and the first space thereof.
It is preferably formed so as to be continuous with the peripheral groove. With this configuration, the hydraulic pressure acting on the spool can be balanced in the axial direction. Moreover, even if the pressure of the pressure oil that has flowed out of the outflow passage fluctuates rapidly due to surging, the outflow passage will face the outer circumference of the spool.
Since it is connected to the circumferential groove of the spool 104, the balance of hydraulic pressure in the axial direction of the spool 104 is not lost. In this case, the opening degree of the throttle section is supposed to change according to the operating condition of the vehicle, and the change of the opening degree of the throttle section acts on the steering assist force generating hydraulic actuator of the hydraulic power steering device of the vehicle. It is preferable to control the hydraulic pressure applied. As a result, smooth displacement of the spool can be ensured and deterioration of steering feeling can be prevented.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

The rack and pinion type hydraulic power steering system 1 shown in FIG. 1 has an input shaft 2 connected to a steering wheel (not shown) and an output shaft 3 connected to the input shaft 2 via a torsion bar 6.
It has and. The torsion bar 6 is connected to the input shaft 2 by the pin 4 and is connected to the output shaft 3 by the serration 5. Its input shaft 2
Are supported by the valve housing 7 via bearings 8 and by the output shaft 3 via bushes 12. The output shaft 3 is a bearing 1
It is supported by the rack housing 9 via 0 and 11. A pinion 15 is formed on the output shaft 3, and a wheel (not shown) is connected to a rack 16 that meshes with the pinion 15. As a result, the rotation of the input shaft 2 due to the steering is transmitted to the pinion 15 via the torsion bar 6.
Be transmitted to. Due to the rotation of the pinion 15, the rack 16 moves in the vehicle width direction. The movement of the rack 16 steers the vehicle. The input / output shaft 2,
3 and the valve housing 7 between the oil seal 42,
43 intervenes. The support yoke 40 that supports the rack 16 is pressed against the rack 16 by the elasticity of the spring 41.

A hydraulic cylinder 20 is provided as a hydraulic actuator for generating steering assist force. The hydraulic cylinder 20 includes a cylinder tube formed by the rack housing 9 and a piston 21 integrated with the rack 16.
It has and. A rotary hydraulic control valve 30 is provided in order to supply pressure oil to the oil chambers 22 and 23 partitioned by the piston 21 according to the steering direction and steering resistance.

The control valve 30 is a cylindrical first valve member 3 which is inserted into the valve housing 7 so as to be rotatable relative to it.
1 and a second valve member 32 which is inserted into the first valve member 31 so as to be rotatable relative to each other about a coaxial center. The first valve member 31 is connected to the output shaft 3 by a pin 29 so as to rotate together. The second
The valve member 32 is formed integrally with the input shaft 2. That is, the outer circumference of the input shaft 2 causes the second
A valve member 32 is configured, and the second valve member 32 rotates together with the input shaft 2. Therefore, the first valve member 3
The first and second valve members 32 relatively rotate about the same axis as the torsion bar 6 is twisted according to the steering resistance.

The valve housing 7 has an inlet port 34 connected to the pump 70, a first port 37 connected to one oil chamber 22 of the hydraulic cylinder 20, and a first port 37 connected to the other oil chamber 23. Two ports 38, a first outlet port 36 directly connected to the tank 71, and a second outlet port 61 connected to the tank 71 via a variable throttle valve 60 described later are provided.

The above-mentioned connection ports 34, 36, 37, 3
8, 61 are connected to each other via an intervalve flow path between the inner and outer circumferences of the first valve member 31 and the second valve member 32.
That is, as shown in FIGS. 3 and 4, the first valve member 3
Eight recesses 50a, 50b, 50c are formed on the inner periphery of the first valve member 1 at equal intervals in the circumferential direction, and eight recesses 51a, 51b, 51c are formed on the outer periphery of the second valve member 32 at equal intervals in the circumferential direction. Has been formed. FIG. 4 shows a developed view of the second valve member 32 by a solid line, and shows recesses 50a, 50b, 50c formed in the first valve member 31 by a chain line. Recesses 50a, 5 formed in the first valve member 31
The recesses 51a, 51b, 51c formed in the second valve member 32 are located between 0b, 50c.

The recesses formed in the first valve member 31 constitute two right steering recesses 50a, two left steering recesses 50b, and four connecting recesses 50c. The two right steering recesses 50a are connected to the right steering assist force generating oil chamber 22 of the hydraulic cylinder 20 via the flow path 53 formed in the first valve member 31 and the first port 37.
They are arranged 180 ° apart from each other in the circumferential direction. The two left steering recesses 50b are connected to the left steering assist force generating oil chamber 23 of the hydraulic cylinder 20 via the flow path 54 formed in the first valve member 31 and the second port 38, and are mutually connected. They are arranged 180 ° apart in the circumferential direction.

The recesses formed in the second valve member 32 are four pressure oil supply recesses 51a, two first pressure oil discharge recesses 51b, and two second pressure oil discharge recesses. 51c. The four pressure oil supply recesses 51a are
It is connected to the pump 70 via the pressure oil supply passage 55 formed in the valve member 31 and the inlet port 34, and is arranged 90 ° apart from each other in the circumferential direction. The two first pressure oil discharge recesses 51b are formed in the flow passage 52 formed in the input shaft 2.
a, passing between the input shaft 2 and the torsion bar 6 and connected to the tank 71 through the flow path 52b (see FIG. 1) formed in the input shaft 2 and the first outlet port 36, and 180 in the circumferential direction. ° Placed apart. Part 2
The second pressure oil discharge concave portion 51c is provided with the first valve member 31.
It is connected to the variable throttle valve 60 via the flow path 59 and the second outlet port 61 formed in the above, and they are arranged 180 ° apart from each other in the circumferential direction. The pressure oil supply passage 55 and the passage 59 formed in the first valve member 31 are formed in a circumferential groove shape on the radially outer side.

Each first pressure oil discharge recess 51b is disposed between the right steering recess 50a and the left steering recess 50b, and each second pressure oil discharge recess 51c is disposed between the communication recess 50c. The pressure oil supply recess 51a is disposed between the right steering recess 50a and the communication recess 50c and between the left steering recess 50b and the communication recess 50c.

Between the edges of the recesses 50a, 50b, 50c formed in the first valve member 31 along the axial direction and the edges of the recesses 51a, 51b, 51c formed in the second valve member 32 along the axial direction. Are the narrowed portions A, A ', B, B', C,
Configure C ', D, D'. As a result, each throttle unit A,
A ′, B, B ′, C, C ′, D and D ′ are inter-valve flow passages 27 that connect the pump 70, the tank 71 and the hydraulic cylinder 20.
It is located in.

As shown in FIG. 5, the second valve member 3 thereof
The edges of the recesses 51a, 51b, 51c formed in 2 along the axial direction are chamfered. The recess 50c for communication
And the throttle portions B ', D'between the second pressure oil discharge concave portion 51c and
The width of the chamfered portion of the edge (enclosed by Δ in FIG. 3) along the axial direction of the second pressure oil discharge concave portion 51c in FIG. 3 is W, and the narrowed portion A ′ between the pressure oil supply concave portion 51a and the communication concave portion 50c. , C ′, the width of the chamfered portion of the edge (enclosed by □ in FIG. 3) along the axial direction of the pressure oil supply recess 51a is W ′,
As shown in FIGS. 4 and 5, W> W ′, where W ″ is the width of the chamfered portion of the edge (encircled by circle in FIG. 3) along the axial direction of the recess formed in the other second valve member 32. > W ″
It is said that. The throttles A, A ', B, B', C, C ', which are in a state without steering resistance (states of FIGS. 4 and 5),
Both valve members 31, 32 required to fully close D, D '
Comparing the relative rotation angles (hereinafter, referred to as “closing angles”) of the two, the connecting recess 50c and the second pressure oil discharge recess 5
The closing angle θr of the throttles B ′ and D ′ with respect to 1c is larger than the closing angle θs of the throttles A ′ and C ′ between the pressure oil supply recess 51a and the communication recess 50c, and both are closed. Angle θ
r and θs are closing angles θ of the other throttle parts A, B, C and D.
greater than t. As a result, each throttle portion between the first valve member 31 and the second valve member 32 has a first set including a plurality of throttle portions A, B, C, and D and each throttle member belonging to the first set. It is divided into a second set consisting of a plurality of throttle parts A ′, B ′, C ′, D ′ having a larger closing angle than the parts A, B, C, D. Further, the throttle portions belonging to the second group have a larger closing angle than the throttle portions A'and C'between the pressure oil supply recess 51a and the communication recess 50c and the throttle portions A'and C '. There are two types of throttle portions B'and D'between the communication recess 50c and the second pressure oil discharge recess 51c.

The input shaft 2 and the output shaft 3 are
The torsion bar 6 is twisted due to the resistance transmitted from the road surface through the wheels, whereby the torsion bar 6 is relatively rotated. The relative rotation causes the first valve member 31 and the second valve member 32 to rotate relative to each other, so that the throttle portions A, B, C, D, A ′, B ′,
The opening degrees of C'and D'change, and the hydraulic cylinder 20 generates a steering assist force according to the steering direction and the steering resistance. The throttle portions A, B, C, D belonging to the first group have smaller closing angles than the throttle portions A ', B', C ', D' belonging to the second group, so that the steering resistance changes. The ratio of change in hydraulic pressure becomes larger.

That is, FIG. 4 shows a state in which steering is not performed. In this state, the throttle portions A, B, C, D, A ', B', C ', D'between the valve members 31, 32 are all opened, and the inlet port 34 and the outlet ports 36, 61 are separated from each other. Since they communicate with each other via the inter-valve flow path 27, the oil flowing from the pump 70 into the control valve 30 flows back to the tank 71, and no steering assist force is generated.

When both valve members 31, 32 rotate relative to each other due to the steering resistance generated by steering to the right from this state, as shown in FIG. 3, the space between the pressure oil supply recess 51a and the right steering recess 50a is increased. The opening of the throttle portion A ′ between the pressure oil supply concave portion 51a adjacent to the throttle portion A and the left steering concave portion 50b and the communication concave portion 50c becomes large, and the right steering concave portion 50a and the first pressure oil discharge. Of the throttle portion B'between the second pressure oil discharge concave portion 51c and the connecting recess 50c adjacent to the pressure oil supply concave portion 51a adjacent to the left steering recess 50b. The opening degree becomes smaller, and the throttle portion C between the pressure oil supply recess 51a and the left steering recess 50b and the throttle between the pressure oil supply recess 51a and the communication recess 50c adjacent to the right steering recess 50a. The opening of section C'becomes smaller and the left Contact recess 5 adjacent to the rudder recesses 50b and the pressure oil supply recess 51a adjacent to the throttle portion D and the right steering recess 50a between the first hydraulic fluid discharge recess 51b
0c and the second pressure oil discharge recess 51c have a large opening of the throttle portion D '. As a result, the flow of pressure oil indicated by the arrow in the drawing supplies pressure oil of a pressure corresponding to the steering direction and steering resistance to the right steering assist force generating oil chamber 22 of the hydraulic cylinder 20, and also the left steering assist force is generated. Oil chamber 23 to tank 71
The oil flows back to the rack 16, and the steering assist force to the right of the vehicle acts on the rack 16 from the hydraulic cylinder 20.

When steered to the left, the first valve member 31 and the second valve member 32 relatively rotate in the opposite direction to those when steered to the right, and the apertures of the throttles A and A'reduce. The apertures of the throttles B and B ′ are increased, the apertures of the throttles C and C ′ are increased, and the apertures of the throttles D and D ′ are decreased.
Therefore, the steering assist force to the left of the vehicle is applied to the hydraulic cylinder 20.
Acts on the rack 16.

As shown in FIGS. 1 and 8, the variable throttle valve 60 communicating with the second outlet port 61 has a second valve housing 7'removable in the valve housing 7 and the second valve housing 7 '. The spool 62 is movably inserted into the insertion hole 66 formed in the axial direction (vertical direction in FIGS. 1 and 8), and the screw member 64 screwed to the spool 62. The center of the spool 62 and the center of the screw member 64 are eccentric to prevent the spool 62 from rotating.

One end of the insertion hole 66 is closed by a plug 68, and the other end is closed by a cover 94 '.
Between the spool 62 and the plug 68, the spool 62
A compression coil spring 90 for preventing rattling is arranged. A stepping motor 80 is connected to the screw member 64, and a controller (not shown) is connected to the stepping motor 80. The controller is connected to a vehicle speed sensor (not shown) and the stepping motor 80
Is controlled according to the vehicle speed. That is, when the speed is high, the screw member 64 rotates in one direction and the spool 62 is displaced upward in the drawing, and when the speed is low, the screw member 64 is rotated in the other direction and the spool 62 is displaced downward in the drawing. As a result, the opening degree of the throttle unit 67, which will be described later, changes according to the vehicle speed that is the operating condition of the vehicle. As described later, the hydraulic pressure acting on the hydraulic cylinder 20 is controlled by the change in the opening degree of the throttle portion 67.

As shown in FIGS. 8 and 9, the insertion hole 66 is formed.
A first circumferential groove 66a is formed on the inner circumference of the so as to face the outer circumference of the spool 62. A second circumferential groove 62a is formed on the outer circumference of the spool 62. One peripheral edge 62a 'of the second peripheral groove 62a is a tapered surface having a smaller diameter as it approaches the other peripheral edge 62a ". One peripheral edge 66a' of the first peripheral groove 66a and the first peripheral groove 66a ' 2 peripheral grooves 62a
A pressure oil throttle portion 67 is formed between the one peripheral edge 62a 'and the one peripheral edge 62a'.

The degree of opening of the throttle portion 67 depends on the spool 6
It changes with the axial displacement of 2. In this embodiment, the opening degree of the throttle portion 67 increases as the speed increases and the spool 62 moves upward in the figure, and decreases as the spool 6 moves downward.
It becomes smaller when 2 is displaced downward.

An outflow passage 76 for the pressure oil, which is continuous with the first circumferential groove 66a, is formed across the valve housing 7 and the second valve housing 7 '. The outflow path 76 is the first
It leads to the exit port 36.

An inflow passage 58 for pressure oil, which is continuous with the second circumferential groove 62a, is formed in the second valve housing 7 '.
The inflow path 58 is connected to the second outlet port 61.

A fluid passage 75 is provided in the spool 62, an internal space 85 of the insertion hole 66 facing one end face of the spool 62, and an insertion hole 66 facing the other end face of the spool 62.
It is formed so as to be continuous with the inner space 86 and the first circumferential groove 66a thereof.

As a result, the pressure oil supplied from the pump 70 reaches the second circumferential groove 62a from the second outlet port 61 of the control valve 30 through the inflow passage 58, and then from the second circumferential groove 62a. The first peripheral groove 66a is reached via the throttle portion 67, and the tank 71 is reached from the first peripheral groove 66a via the outflow passage 76 and the first outlet port 36.

The maximum value of the opening of the throttle section 67 is the maximum value of the total opening of the throttle sections A ', B', C'and D'belonging to the second set (relative to both valve members 31, 32). It is the maximum value in the characteristic that the opening degree decreases as the rotation angle increases.
That is, it means the maximum value of the total opening of the throttles B'and C'when steering right, and the maximum of the total opening of the throttles A'and D'when steering left. Hereinafter, the term “maximum value of total opening” means the same or more, or is increased until the throttle function is no longer achieved. The minimum value of the opening of the throttle 67 is the second value.
Of the throttles A ', B', C ', D'belonging to the set (the minimum value in the characteristic that the opening decreases as the relative rotation angle of both valve members 31, 32 increases). That is, it means the minimum value of the total opening of the throttle parts B'and C'when steering to the right, and the minimum value of the total opening of the throttle parts A'and D'when steering to the left. Included in the following, when the term "minimum value of the total opening" means the same)

As a result, the hydraulic circuit shown in FIG. 2 is constructed, and the opening degree of the oil passage between the throttle portions A ', B', C ', D'belonging to the second set and the tank 71 is the vehicle speed. It is changed by the operation of the variable throttle valve 60 according to. That is, the pressure oil flow rate controlled by the throttle portions A, B, C, D belonging to the first group, the pressure controlled by the throttle portions A ', B', C ', D' belonging to the second group. The ratio to the oil flow rate is the variable throttle valve 6
It changes with the operation of 0.

In FIG. 7, a solid line X indicates both valve members 3
The change characteristic of the opening degree of the throttle parts A, B, C, and D belonging to the first set with respect to the relative rotation angles of 1 and 32 is shown. One-dot chain line U
Shows a change characteristic of the opening degree of the throttle portions B'and D'between the connection recess 50c and the second pressure oil discharge recess 51c belonging to the second set with respect to the relative rotation angle. The alternate long and short dash line V indicates the change characteristic of the opening degree of the throttle portions A ′ and C ′ between the pressure oil supply concave portion 51 a and the communication concave portion 50 c belonging to the second group with respect to the relative rotation angle. The solid line Y indicates that all the throttle parts A ', B', C ', belonging to the second set with respect to the relative rotation angle,
The combined change characteristic of the opening of D'is shown. It should be noted that the change characteristic of each opening in FIG. 7 becomes smaller as the relative rotation angle becomes larger, as is apparent from the change characteristic of the throttle portions B, B ′, C, and C ′ during right steering. The change characteristics of the diaphragm portions A, A ′, D, and D ′ are shown during left steering. The broken line R indicates the opening degree of the variable throttle valve 60 set by the variable throttle valve 60 when the throttle portion 67 is running at medium speed.

According to the first power steering device 1 described above, the spool 62 is displaced downward in FIGS. 1 and 8 when the vehicle is traveling at a low speed, and the displacement of the spool 62 causes the throttle portion 67 of the variable throttle valve 60 to move. Fully closed. Therefore, the hydraulic pressure acting on the hydraulic cylinder 20 is controlled according to the change characteristic line X of the opening degree of the throttle portions A, B, C, D of the first set. In this case, as shown by the alternate long and short dash line in FIG.
Even if the steering input torque is small and the relative rotation angles of both valve members 31 and 32 are small, the throttle portions A belonging to the first group,
It is possible to reduce the opening degrees of B, C, and D and increase the increase rate of the hydraulic pressure that generates the steering assist force, thereby satisfying the high responsiveness of steering during low speed traveling.

During high-speed traveling, the spool 62 is displaced upward in FIGS. 1 and 8, and the displacement of the spool 62 causes the opening of the throttle portion 67 of the variable throttle valve 60 to reach the second position.
Is greater than or equal to the maximum value of the total opening degree of the throttle portions A ', B', C'and D'belonging to the set. Therefore, the hydraulic pressure acting on the hydraulic cylinder 20 is the second set of throttle portions A ', B', C ', D'.
Of the opening change characteristic line Y and the first set of throttle portions A, B,
The control is performed according to the combined characteristic of the change characteristic line X of the opening degrees of C and D. In this case, as shown by the solid line in FIG. 6, unless the steering input torque is increased and the relative rotation angles of the two valve members 31, 32 are increased, the throttle portions A ′, B ′, C ′ belonging to the second set. , D ′ are kept large without decreasing, and the increase rate of the hydraulic pressure for generating the steering assist force is small, so that the steering stability can be satisfied during high-speed traveling.

During traveling at medium speed, the opening of the throttle portion 67 of the variable throttle valve 60 due to the displacement of the spool 62 is the total opening of the throttle portions A ', B', C'and D'belonging to the second group. It is larger than the minimum value and smaller than the maximum value. As a result, as shown in FIG. 7, the diaphragm units A belonging to the first group,
Until the total opening of B, C, D reaches the minimum value (fully closed state in this embodiment) (until the relative rotation angle of both valve members becomes θa in FIG. 7), The steering assist force according to the characteristic obtained by synthesizing the characteristic line X of the change of the total opening of the throttle portions A, B, C, D belonging to the group of No. Diaphragm parts A and B belonging to the first group,
From the time when C and D are in the fully closed state, the total opening degree of the throttle portions A ′, B ′, C ′ and D ′ belonging to the second set is smaller than the opening degree of the throttle portion 67 of the variable throttle valve 60. Until it becomes smaller (the relative rotation angle of both valve members is between θa and θb in FIG. 7), the steering assist force becomes a constant value determined by the opening degree of the throttle portion 67. Thereafter, when the total opening of the throttle parts A ′, B ′, C ′, D ′ belonging to the second set becomes smaller than the opening of the throttle part 67 of the variable throttle valve 60, the throttle parts belonging to the second set. A steering assist force corresponding to the change characteristic line Y of the total opening of the parts A ′, B ′, C ′, D ′ is applied.

The diaphragm portions A, B, C belonging to the first set
After the fully closed state of D, the total opening of the throttle parts A ′, B ′, C ′, D ′ belonging to the second set becomes smaller than the opening of the throttle part 67 of the variable throttle valve 60. Between (θa ~ θ
b)), the narrowed portions A ', B', which belong to the second set,
The difference between the point where C ′ and D ′ are fully closed and the point where the throttle units A, B, C, and D belonging to the first set are fully closed (θc−
θa) is made small without being made small. That is, if the throttle portions A ′ and C ′ between the pressure oil supply concave portion 51a and the communication concave portion 50c belonging to the second group are between the communication concave portion 50c and the second pressure oil discharge concave portion 51c. Assuming that the throttle portions B ′ and D ′ of FIG. 4 have opening change characteristics with respect to the relative rotation angle indicated by the one-dot chain line U in the figure, all the throttle portions A ′ belonging to the second set with respect to the relative rotation angle, B ',
The combined change characteristic of the total opening of C'and D'is shown by the chain double-dashed line M in FIG. Then, until the opening degree of the throttle portions A ′, B ′, C ′, D ′ belonging to the second set becomes smaller than the opening degree of the throttle portion 67 of the variable throttle valve 60 itself (both valve members). Since the relative rotation angle of (between θa and θd) becomes large, as shown by the chain double-dashed line in FIG. 6, the steering assist force cannot be controlled in accordance with the steering resistance.
Grows larger. On the other hand, in the above-described embodiment, the closing angle θs of the throttle portions A ′ and C ′ between the pressure oil supply recessed portion 51a and the communication recessed portion 50c belonging to the second set is the same as that of the communication recessed portion 50c. Since it is smaller than the closing angle θr of the throttles B ′ and D ′ with the pressure oil discharge recess 51c, it is possible to reduce the region where the steering assist force cannot be controlled according to the steering resistance during medium speed running. Moreover, the throttle portions A'and C'between the pressure oil supply recess 51a and the communication recess 50c are in a fully closed state (in FIG. 7, the relative rotation angle of both valve members is θe.
Point), the connection recess 50c and the second pressure oil discharge recess 5
Since the throttle portions B'and D'with 1c are not closed yet, the area where the steering assist force can be controlled according to the steering resistance is not reduced.

According to the variable throttle valve 60 having the above structure, the pressure oil reaches the first circumferential groove 66a from the second circumferential groove 62a through the throttle portion 67. One peripheral edge 62 of the second peripheral groove 62a
a'is a tapered surface having a diameter that decreases as it approaches the other peripheral edge 62a ".
The area of the channel becomes smaller toward the downstream side. Therefore,
As shown in FIG. 9, even when the opening of the throttle 67 is small,
In the throttle portion 67, the pressure of the pressure oil gradually decreases.
As a result, it is possible to suppress the generation of cavitation bubbles in the pressure oil and reduce the noise accompanying the flow of the pressure oil. Also,
Since the tapered surface forming the narrowed portion 67 is formed on the outer circumference of the spool 62, it is not necessary to machine the inner circumference of the hole.
Processing is not difficult. Also, the spool 62
In the inner space 85 of the insertion hole 66 facing one end surface of the spool 62, the inner space 86 of the insertion hole 66 facing the other end surface of the spool 62, and the first circumferential groove 66a. Since it is formed so as to be continuous,
The hydraulic pressure acting on the spool 62 can be balanced in the axial direction. Moreover, even if the pressure of the pressure oil that has flowed out from the outflow passage 76 suddenly fluctuates due to surging, the outflow passage 76 continues to the first circumferential groove 66a facing the outer circumference of the spool 62, so that the axial direction of the spool 62 is increased. The balance of hydraulic pressure at will not be lost. This allows
It is possible to secure a smooth displacement of the spool 62 according to the vehicle speed and prevent a reduction in steering feeling.

The present invention is not limited to the above embodiment. For example, although the spool is displaced according to the vehicle speed in the above embodiment, it may be displaced according to other operating conditions such as the steering angle. The variable throttle valve of the present invention may be used in a hydraulic circuit of a hydraulic device other than the hydraulic power steering device.

[0043]

According to the present invention, it is possible to provide a variable throttle valve capable of reducing the generation of noise associated with the flow of pressure oil and ensuring a smooth displacement of a spool without performing difficult processing. Also,
When controlling the hydraulic pressure that acts on the hydraulic actuator for generating the steering assist force of the hydraulic power steering device by the variable throttle valve, it is possible to prevent the steering feeling from deteriorating.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a hydraulic power steering device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a hydraulic circuit of the hydraulic power steering device according to the embodiment of the present invention.

FIG. 3 is an explanatory view of a cross-sectional structure of a control valve in the hydraulic power steering device according to the embodiment of the present invention.

FIG. 4 is a development view of a control valve in the hydraulic power steering system according to the embodiment of the present invention.

FIG. 5 is an enlarged view of a main part of a control valve of the hydraulic power steering device according to the embodiment of the present invention.

FIG. 6 is a diagram showing a relationship between an input torque and a hydraulic pressure and a relationship between a relative rotation angle of both valve members and a hydraulic pressure in the hydraulic power steering device according to the embodiment of the present invention.

FIG. 7 is a diagram showing the relationship between the opening degree of the throttle of the control valve and the relative rotation angle of the valve member in the hydraulic power steering system according to the embodiment of the present invention.

FIG. 8 is a vertical sectional view of a variable throttle valve of the hydraulic power steering device according to the embodiment of the present invention.

FIG. 9 is a sectional view of a main part of a variable throttle valve of the hydraulic power steering system according to the embodiment of the present invention.

FIG. 10 is a longitudinal sectional view of a conventional variable throttle valve housing.

[Explanation of symbols]

1 Hydraulic power steering device 7'Second valve housing 20 hydraulic cylinder 58 Inflow path 60 variable throttle valve 62 spool 62a Second circumferential groove 62a ″ edge 66 insertion hole 66a First circumferential groove 66a 'periphery 67 Aperture 75 fluid passage 76 Outflow path 85 Internal space 86 Internal space

─────────────────────────────────────────────────── ───Continued from the front page (56) References JP-A-8-159323 (JP, A) JP-A-9-166231 (JP, A) Actually open 62-161083 (JP, U) Actually open 63- 27726 (JP, U) Actual development Sho 56-65264 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) F16K 3/24 F16K 3/32 B62D 5/083

Claims (2)

(57) [Claims] 1. A housing, and a spool which is inserted into an insertion hole formed in the housing so as to be axially displaceable, and a first circumferential groove faces an outer circumference of the spool at an inner circumference of the insertion hole. A second peripheral groove is formed on the outer periphery of the spool, and one peripheral edge of the second peripheral groove is a tapered surface that becomes smaller in diameter as it approaches the other peripheral edge. Between the one peripheral edge of the peripheral groove and the one peripheral edge of the second peripheral groove is a throttle portion for the pressure oil, and the opening degree of the throttle portion changes according to the axial displacement of the spool. in its outflow path of the pressurized oil so as to be continued to the first circumferential groove is formed, the inflow passage of the pressurized oil so as to be continued in the second circumferential groove is formed, the fluid passages on the spool, the spool Pair on one end
Face the inner space of the facing insertion hole, the other end surface of the spool
To the inner space of the insertion hole and the first circumferential groove.
A variable throttle valve, which is characterized in that 2. The opening of the throttle portion depends on the driving conditions of the vehicle.
Change due to the change in the opening of the throttle.
The steering assist of the hydraulic power steering system of the vehicle.
Controls the hydraulic pressure acting on the force-generating hydraulic actuator
The variable throttle valve according to claim 1 .