JPH05170125A - Steering force control device for power steering - Google Patents

Abstract

PURPOSE:To provide a steering device capable of realizing a desired valve characteristic without forming a chamfering section at the control projection of a control valve CV. CONSTITUTION:A power steering control device is constituted of a control valve CV switched in response to the operation angle of a steering wheel, a power cylinder C operated in response to this switch quantity, and a controller 49. The power assist force corresponding to the change of the load pressure of the power cylinder C is controlled by a flow priority valve 43 and a pressure sensor 50 provided between a pressure control valve 47 controlled by the controller 49 connected to the control flow side 45 of the flow priority valve 43 and the power cylinder C connected to the excess flow side 46 of the flow priority valve 43.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steering force control device for controlling a steering force according to a steering angle of a steering wheel.

[0002]

2. Description of the Related Art The conventional device shown in FIGS. 6 to 11 is a power steering device using a rotary valve V as a control valve CV. This device is a casing 1
In addition, the pinion shaft 2 and the stub shaft 3 are coaxially inserted, and both shafts 2 and 3 are connected via a torsion bar 4. A pinion 5 is formed on the pinion shaft 2 and the pinion 5 is engaged with a rack 7 formed on a rod 6 of a steering system. Therefore, when the pinion shaft 2 rotates and the pinion 5 rotates, the rod 6 moves accordingly and steers the front wheels (not shown).

The stub shaft 3 rotates integrally with a steering wheel (not shown), and a rotary valve V is provided around it. The rotary valve V includes a spool 8 that is integrated with the stub shaft 3 and a sleeve 9 that is relatively rotatably fitted to the spool 8. This sleeve 9 is connected to the pinion shaft 2 via a pin 10 so that they both rotate integrally. Further, the spool 8 is, as shown in FIG.
A plurality of recesses 11 to 1 are arranged at a predetermined interval in the circumferential direction.
8 are formed, and the portions located between these concave portions 11 to 18 are control convex portions 19 to 26. Of the recesses thus formed, every other recess 12, 14, 16, 18 has a tank passage 2 formed at the center of the spool 8.
It communicates with 7.

Further, the inner periphery of the sleeve 9 is formed with the same number of control grooves 28 to 35 as the control convex portions. And
Each of the control grooves 28, 30, 32, 34 is made to communicate with one pressure chamber 36 of the power cylinder C, and the control grooves 29, 3
1, 33, 35 are communicated with the other pressure chamber 37.
Furthermore, between the control grooves 29, 30, between 31, 32, 33, 3
A supply port 38 that communicates with the pump P is opened between each of 4 and between 35 and 28. Note that FIG.
Is an equivalent circuit diagram.

When the steering wheel (not shown) is held in the neutral position in the above structure, the rotary valve V maintains the position shown in FIG. The fluid discharged from the pump P in this state is supplied from the supply port 38 →
The recesses 11, 13, 15, 17 → the control grooves 28 to 35 → recesses 12, 14, 16, 18 → returned to the tank T via the tank passage 27, and the power cylinder C is also kept in the neutral position. When the steering wheel is operated from the above state, the stub shaft 3 rotates and the rotational force thereof is also transmitted to the pinion shaft 2 via the torsion bar 4. However, the rotation of the pinion shaft 2 is hindered by the ground friction of the wheels or the like, so that the torsion bar 4 is twisted accordingly. Therefore stub shaft 3
Rotates more than the pinion shaft 2 by the twist angle of the torsion bar 4. That is, both shafts 2,
3 will rotate relative to each other.

As the shafts 2 and 3 rotate in this manner, the spool 8 and the sleeve 9 also rotate relative to each other, so that the rotary valve V is switched. For example, if the spool 8 turns to the right in FIG. Then it becomes as follows. When the spool 8 rotates to the right from the state shown in FIG. 7, the passage that connects the supply port 38 and the control grooves 28, 30, 32, 34 to each other expands, and the control grooves 28, 3
The passages connecting the 0, 32, 34 with the recesses 12, 14, 16, 18 are reduced. Therefore, the fluid discharged from the pump P is supplied from the supply port 38 to the concave portions 11, 13, 15, 1
7 → Supplied to one pressure chamber 36 of the power cylinder via the control grooves 28, 30, 32, 34. At this time, the control grooves 29, 31, 33, 35 and the recesses 12, 14, 16, 1
Since the passage communicating with 8 is expanded, the working fluid in the other pressure chamber 37 of the power cylinder C flows into the control grooves 29, 3
1, 33, 35 → recesses 12, 14, 16, 18 → returned to the tank via the tank passage 27. Then, these flows are indicated by arrows in the equivalent circuit of FIG.

Therefore, the piston rod 39 of the power cylinder C moves and the rod 6 of the steering system moves.
To steer the front wheels. If the steering wheel is continuously rotated, the pinion shaft 2 and the stub shaft 3 rotate integrally while maintaining the relative rotation angle, and the pinion 5 rolls on the rack 7. When the steering wheel is stopped in this state, the rotary valve V is placed at a position where it is balanced with the load on the tire side due to ground contact friction at that time.
Remains switched, and the power cylinder C also stops at the switching position. In this state, when the steering wheel is released from the steering wheel or operated to return it, the rotary valve V returns to the neutral position due to the torsional reaction force of the torsion bar 4, etc., and due to the returning force from the tire side, etc. C also returns to the neutral position.

In this type of device, when the steering angle is small,
In other words, when the operating angle of the rotary valve V is small, the pressure of the power cylinder C is kept low and the power assist force is reduced. Generally, if the steering angle is small, the steering wheel can be turned with a small force even at a low speed. On the other hand, when driving at high speed, it is dangerous to turn the steering wheel too much, so that is not the case. Therefore, in the case of this device, when the steering angle is small, the power assist force is reduced to improve the maneuverability. Further, since the steering wheel is largely cut only at low speed running, the pressure of the power cylinder C is increased when the operating angle of the rotary valve V is large.

In order to keep the pressure of the power cylinder C low and the power assisting force small when the valve operating angle is small as described above, in this conventional example, as shown in FIG. The chamfered portions 40 are formed on the edges 26 to 26. This chamfer processing section 40 is
The horizontal part h that was cut horizontally from the edge tip and this horizontal part h
From the inclined portion i toward the central portion of the control convex portion. By doing so, for example, when the spool 8 relatively rotates in the direction of the arrow in FIG. 8, the opening area of the opening m formed by the control convex portion and the control groove is gradually reduced. 9 shows the relationship between the operating angle of the rotary valve V and the opening area of the opening m.
As is apparent from FIG. 9, as the spool 8 rotates and the edge portions of the control convex portions 19 to 26 approach the control grooves 28 to 35, the opening area decreases along the characteristic of the straight line (1). If the horizontal portion h and the inclined portion i are disengaged from the control groove and are wrapped with the sleeve, the opening area is reduced along the characteristic of the straight line (2). The control characteristic of the working pressure of the power cylinder C according to the change of the opening area is shown in FIG.
This is as indicated by the solid line of 0. In this way, the control pressure of the power cylinder C has the characteristics shown by the solid line in FIG. 10, so that when the valve operating angle is small, for example, the pressure change within the range of x in FIG. 10 becomes too large. In reality, this is ideal because the characteristics shown by the alternate long and short dash line in FIG. 10 can be obtained. That is, in the range x where the valve operating angle is small,
Ideally, the control pressure rises gently, and the control pressure rises sharply from the time point when the range x is exceeded. However, the above-mentioned conventional example has a problem that it is difficult to maintain maneuverability in the range x where the valve operating angle is small, particularly when traveling at high speed.

In order to solve this point, the present applicant has already provided the invention according to Japanese Patent Application No. 2-136237, which is shown in FIGS. A conventional example will be described. The rotary valve V has recesses 11 to 18 and control projections 19 to 26 formed on the spool 8 and control grooves 28 to 35 formed on the sleeve 9, but these recesses 11 to 18 and control projections 19 are formed. .. 26 and control grooves 28 to 35, respectively, constitute a first control unit I and a third control unit III as shown in FIG.

The first control section I has its control projections 19-.
The edge portion of 26 is chamfered as shown in FIG. 13 to form the chamfered portion 40, and the length of the chamfered portion 40 is L ₁ . And
When the valve V is in the neutral position, the chamfering portion 40
The distance from the edge portion to the control groove of the sleeve 9, that is, the amount of underlap is U ₁ . The rotary valve V is switched in either direction to reduce the opening area of the passage leading to the tank passage 27 and increase the opening area of the passage leading to the power cylinder C. A chamfered portion 41 is also formed on the edge portion of the control convex portion of the third control portion III as shown in FIG. 13, and the length of the chamfered portion 41 is L ₂ . Also, when the valve V is in the neutral position, the chamfered portion 41 moves from the edge portion to the sleeve 9
The distance to the end of the control groove, that is, the amount of underlap, is set to U ₂ sufficiently large. The third control unit III thus configured is connected to the pump P via the fixed throttle 42 as the stage 2 control unit II formed on the sleeve 9. The equivalent circuit of this configuration is shown in FIG.

If the steering wheel is held in the neutral position, the rotary valve V also holds the neutral position in the figure, so that the fluid discharged from the pump P passes from the supply port 38 through the first control section I and the tank passage 27. It is returned to the tank T. Therefore, as shown in FIG. 14A, almost no pressure is generated in the power cylinder C.

When the steering wheel is turned from the above state to switch the rotary valve V, the following is obtained. Now, when the valve operating angle is small, such as when traveling at medium and high altitudes, the opening area of the first control section I is small, but the opening area of the third control section III is only small to the extent that it does not affect the throttling effect. Therefore, at this time, the pressure is controlled by the first control unit I and the second control unit II, but a predetermined flow rate flows out to the tank T from the fixed throttle 42 which constitutes the second control unit II. Therefore, the characteristics of each valve operation and the pressure of the power cylinder C are shown in FIG.
It becomes like (b).

Further, when the steering wheel is greatly turned for traveling at low speed, the opening degree of the third control unit III is reduced this time, and the flow rate of returning to the tank is suddenly reduced. ), The pressure of the power cylinder C rises sharply. As described above, the valve operating angle is small in the range (a) where the vehicle is running straight or is in a slight steering state, so that almost the entire amount of discharge of the pump P is generated by the first controller I.
The pressure of the power cylinder C hardly rises as it is returned to the tank via. Therefore, according to this conventional example, since the pressure increase of the power cylinder C is gentle until the steering torque reaches a certain level or more, the steering characteristics are stable during straight traveling and medium-high speed traveling. Also,
The steering reaction force when the steering wheel is operated is given by the spring reaction force of the torsion bar 4 or the like.

[0015]

As described in the above-mentioned conventional example, when the steering angle is small, the power assist force is reduced to improve the maneuverability, and when the vehicle is traveling at a low speed when the steering wheel is greatly cut, the power assist is provided. In order to increase the force, the characteristics of the solid line portion of FIG. 10 are realized in the conventional examples of FIGS. That is, the chamfered portion 40 is formed on the edge portion of the control convex portions 19 to 26 of the rotary valve V, and the chamfered portion 40 controls the supply flow rate to the power cylinder C to show the characteristics of the solid line portion in FIG. Has been realized. However, ideally, it is desired to realize the characteristic indicated by the alternate long and short dash line in FIG. Therefore, as in the conventional example shown in FIGS. 12 to 15, the characteristics as shown in FIG. 14 are realized by using different types of chamfered processing portions 40 and 41 and the fixed diaphragm 42.
The ideal characteristics indicated by the chain line of 0 are realized.

However, the chamfered portions 40 and 41 are
The chamfered portions 40, 4 must be formed on the edge portions of the very small control projections 19 to 26.
Since the valve characteristic as shown in FIG. 14 is determined by the shape of No. 1, the processing technique requires high precision and high measurement technique. Therefore, there is a problem that the production cost is high. There is also a problem in that the desired valve characteristics may not be realized in some cases due to such processing technology and measurement technology restrictions.

The object of the present invention is to control valve C.
It is an object of the present invention to provide a power steering device that can achieve desired valve characteristics without forming a chamfered portion on the V control convex portion.

[0018]

In order to solve the above problems, according to the present invention, a stub shaft that rotates integrally with a steering wheel, a rod of a steering system, and a pinion shaft having a pinion that meshes with the rod are provided. Steering force of a power steering including a control valve that switches according to the operating angle of the steering wheel, a power cylinder that operates according to the switching position of the control valve, and a controller to which an external signal such as vehicle speed is input. In the control device, a pressure control valve controlled by the controller, a hydraulic reaction chamber that is controlled by the pressure control valve and applies a hydraulic reaction force to the steering wheel, and according to the differential pressure before and after the throttle provided inside, Provided with a flow priority valve that changes the outflow rate between the control flow side and the surplus flow side The control flow side of this flow priority valve and the pressure control valve are connected, and the surplus flow side of the flow priority valve is connected via a control valve, and the load of the power cylinder is connected between these flow priority valve and power cylinder. By providing a pressure sensor that detects changes in pressure and connecting this pressure sensor to the controller, the controller controls the pressure control valve according to the change in the load pressure of the power cylinder, and the differential pressure before and after the flow priority valve is controlled. It is characterized in that the flow rate is changed to control the supply flow rate to the power cylinder, and the power assist force of the power cylinder and the pressure acting in the hydraulic reaction force chamber are controlled correspondingly.

[0019]

Since the present invention is configured as described above, when the steering wheel is operated, the control valve is switched, and the power cylinder operates according to the switching position. At this time, the pressure sensor detects a change in the load pressure of the power cylinder and sends the information to the controller. The controller controls the pressure control valve by judging from the information and other external signals, and controls the pressure downstream of the control priority side of the flow priority valve. This pressure control changes the differential pressure before and after throttling in the flow priority valve, and accordingly determines the flow rate supplied from the surplus flow side of the flow priority valve to the power cylinder via the control valve.

In this way, if the supply flow rate from the surplus flow side of the flow priority valve to the power cylinder is determined,
The power assist force of the power cylinder is also determined according to the switching position of the control valve. In other words, according to the change in the load pressure of the power cylinder detected by the pressure sensor,
The flow priority valve controls the supply flow rate to the power cylinder and controls the power assist force. At the same time, the pressure acting in the hydraulic reaction force chamber is controlled by the pressure control valve, so that the hydraulic reaction force corresponding to the power assist force of the power cylinder can be obtained.

[0021]

1 to 5 are embodiments of the present invention. The same components as those in the conventional example described above are designated by the same reference numerals, and detailed description thereof will be omitted. Also, in the case of using the conventional example for description, the same drawings and reference numerals are used.

FIG. 1 is a circuit diagram of the present invention. Also,
2 to 3 show the first embodiment, and FIGS. 4 and 5 show the second embodiment. The circuit diagram of FIG. 1 is common to the first and second embodiments. The first embodiment uses the rotary valve V shown in the conventional example as the control valve CV, and the second embodiment uses the sliding valve V '.

In FIG. 1, a throttle 44 is provided in the flow priority valve 43 connected to the pump P. The downstream side of the throttle 44 is the control flow side 45, and the upstream side is the surplus flow side 46. This flow priority valve 43
Preferentially supplies the set constant flow rate to the control flow side 45 and supplies a higher flow rate to the surplus flow side 46. However, the flow rate of the surplus flow side 46 changes depending on the change in the differential pressure before and after the throttle 44. It is decided. In the flow priority valve 43 used in this embodiment, when the pressure difference before and after the throttle 44 is large, the flow rate on the excess flow side 46 is large, and conversely, when the pressure difference is small, the flow rate on the excess flow side 46 is small. Become. Also,
The control flow side 45 is connected in parallel with the pressure control valve 47 and the hydraulic reaction force portion 48. The pressure control valve 47 is connected to the controller 49 and controlled by a signal from the controller 49. The hydraulic reaction force section 48 applies a steering reaction force to a steering wheel (not shown) by the pressure acting on the hydraulic reaction force chamber 53.

The surplus flow side 46 of the flow priority valve 43 is connected to the rotary valve V, and the downstream side of the rotary valve V is connected to the power cylinder C and the tank T. The switching amount of the rotary valve V is determined according to the operation amount of the steering wheel. And
When the steering wheel is not operated, the rotary bubble V is in the neutral position, and all the oil flowing in the rotary valve V returns to the tank T.

A pressure sensor 50 is provided between the rotary valve V and the excess flow side 46 of the flow priority valve 43. The pressure sensor 50 is connected to the controller 49. As a result, the pressure sensor 5
0 detects a change in the load pressure of the power cylinder C that operates according to the switching amount of the rotary valve V, and sends that information to the controller 49. Further, desired valve characteristics as shown in FIG. 10 are set in the controller 49. In order to realize this valve characteristic, the connected device is controlled based on the pressure sensor 50 and information such as vehicle speed.

The operation of this embodiment configured as described above will be described. The hydraulic oil supplied from the pump P flows into the flow priority valve 43. The hydraulic oil that has flowed into the flow priority valve 43 flows out from the control flow side 45 through the throttle 44, but the surplus flow rate above the set flow rate is
It is supplied to the rotary valve V from the surplus flow side 46. The hydraulic oil flowing out from the control flow side 45 is directed to the pressure control valve 47 and the hydraulic reaction force portion 48. Since the controller 49 determines the state of the vehicle from an external signal such as the vehicle speed and controls the pressure control valve 47, for example, when the controller 49 determines that the vehicle speed is low, the pressure control valve 47 is located upstream thereof. The pressure is controlled so that it becomes small. This pressure control valve 47
The pressure controlled by acts on the hydraulic reaction force portion 48, and acts on the steering wheel as a small reaction force.

At the same time, the same pressure acting on the hydraulic reaction force portion 48 also acts on the flow priority valve 43. Therefore, the differential pressure before and after the throttle 44 in the flow priority valve 43 changes. The supply flow rate to the surplus flow side 46 also changes according to the change in the differential pressure across the throttle 44. That is, the pressure control valve 47 controlled by the control valve 49 controls the set flow rate on the control flow side 45 of the flow priority valve 43.

As described above, in the flow priority valve 43, the differential pressure before and after the throttle 44 changes due to the pressure controlled by the pressure control valve 47, and in accordance with the change in the differential pressure, the excess flow from the surplus flow side 46 side. The flow rate is decided. Therefore, the hydraulic fluid whose flow rate is controlled from the surplus flow side 46 of the flow priority valve 43 according to the control pressure of the pressure control valve 47 goes to the power cylinder C via the rotary valve V. The rotary valve V determines a switching amount according to the operation amount of the steering wheel, and also determines the power assisting force of the power cylinder C according to the switching amount.

In the conventional example, in order to realize the valve characteristic of the one-dot chain line portion within the range of x shown in FIG. 10, chamfering processing portions 40 and 41 are provided at the edge portions of the control convex portions 19 to 26.
To control the supply flow rate to the power cylinder C. That is, in FIG. 8, the flow rate is controlled by the chamfered opening m that changes according to the valve operating angle, and the power assist force of the power cylinder C is controlled. However, in the present invention, the flow priority valve 43 controls the flow rate supplied to the rotary valve V without forming the chamfered portions 40 and 41. That is, the actual load pressure of the power cylinder C is fed back to control the pressure control valve 47, and the flow priority valve 43 is controlled according to the control pressure of the pressure control valve 47 to be supplied to the power cylinder C. The flow rate is controlled. By controlling the flow rate in this manner, linear characteristics within the range of x in FIG. 10 are obtained. In other words, conventionally, the linear characteristic is obtained only by depending on the switching amount of the rotary valve V, but in this embodiment, in addition to the switching amount of the rotary valve V, the load pressure of the power cylinder C is also increased. Is also a parameter.

The steering reaction force is given by the pressure controlled by the pressure control valve 47 acting on the hydraulic reaction force portion 48. As described above, the power assisting force of the power cylinder C is
Based on information such as the pressure sensor 50 input to the controller 49 and the vehicle speed, the flow rate flowing out from the surplus flow side 46 of the flow priority valve 43 according to the switching amount of the rotary valve V and the control pressure of the pressure control valve 47. Controlled by and. In this case, the pressure controlled by the pressure control valve 47 is equal to the pressure controlled by the flow priority valve 43.
And the hydraulic reaction force portion 48. Therefore, the steering reaction force and the power assist force of the power cylinder C have corresponding magnitudes.

The embodiment operating in this way shows the case of traveling at low speed and high speed. First, when traveling at low speed, a large steering angle is often taken. In such a case, the ground resistance of the tire is large, so the power assist force must be large. On the contrary, unless the steering reaction force is small, it is difficult to operate. Therefore, when traveling at a low speed, the controller 49 determines that the vehicle speed is low, controls the pressure control valve 47 to increase the opening degree, and controls the flow with the hydraulic reaction force portion 48 connected upstream of the pressure control valve 47. Priority valve 43
The pressure with the control flow side 45 of is maintained low. Since the pressure in the hydraulic reaction force chamber 53 in the hydraulic reaction force portion 48 is low, the steering reaction force when the steering wheel is largely operated to operate the switching amount of the rotary valve V becomes small. At the same time, the control flow side 45 of the flow priority valve 43
Since the pressure is low, the differential pressure before and after the throttle 44 in the flow priority valve 43 becomes large. Therefore, the opening degree of the surplus flow side 46 becomes large, the flow rate supplied to the power cylinder C increases, and a large power assist force can be obtained.

At this time, the pressure sensor 50 detects the load pressure of the power cylinder C and sends the information to the controller 49. The controller 49 controls the pressure control valve 47 to operate the power cylinder C from the information and the information such as the vehicle speed so as to match the valve characteristics. Further, the pressure controlled by the pressure control valve 47 acts on the hydraulic reaction force portion 48 and the flow priority valve 43.
In this way, the load pressure of the power cylinder C is constantly fed back so as to match the set valve characteristic, so that the power assist force corresponding to the vehicle speed and the steering amount can always be obtained and the power assist force can be supported. It is possible to obtain the steering reaction force.

Further, during high speed running, the tire receives a small ground contact resistance and the steering wheel is not greatly cut off. Therefore, it is preferable that the power assist force is small and the steering reaction force is large. In such a case, the controller 49 determines that the vehicle speed is high and outputs a signal for adjusting the opening degree of the pressure control valve 47 to generate a high pressure.
Control 7 The high pressure controlled by the pressure control valve 47 acts on the hydraulic reaction force chamber 53 of the hydraulic reaction force portion 48 and the control flow side 45 of the flow priority valve 43. As a result, a large steering reaction force acts on the steering wheel that operates a small switching amount of the rotary valve V. At the same time, the high pressure controlled by the pressure control valve 47 acts on the control flow side 45 of the flow priority valve 43. Due to this high pressure, the differential pressure before and after the throttle 44 becomes small, and the flow rate flowing out from the surplus flow side 46 is limited to a small amount. The limited supply flow rate from the surplus flow side 46 is supplied to the power cylinder C through the rotary valve V with a small switching amount. Since the flow rate supplied to the power cylinder C is small, the power assist force is small.

Also at this time, the pressure sensor 50 detects the load pressure of the power cylinder C, feeds it back to the controller 49, judges from other information such as the vehicle speed, and controls the pressure control valve 47 so as to match the valve characteristics. To do. The pressure controlled by the pressure control valve 47 acts on the hydraulic reaction force portion 48 and the control flow side 45 of the flow priority valve 43.
In this way, the load pressure of the power cylinder C is constantly detected and fed back so as to match the valve characteristics.

2 and 3 show the hydraulic reaction force portion 48 of the first embodiment using the rotary valve V. As shown in FIG. 2 and 3, the stub shaft 3 and the pinion shaft 2 are coaxially connected as in the conventional example, but the torsion bar 4 is not interposed. In this respect, unlike the conventional example, the reaction force is applied by the hydraulic reaction force portion 48. As shown in FIG. 3, the hydraulic reaction force chamber port 59 formed in the casing 1 is
It is connected to the flow priority valve 43 and the pressure control valve 47, and guides pressure to the hydraulic reaction force chamber 53. The reaction force plunger 52 is supported by the end support member 54 and the intermediate support member 55 formed on the casing 1. Further, the stub shaft 3 is formed with a convex portion 51. From the left and right in the figure, the reaction force plunger 5
2 is pressed by the pressure action in the hydraulic reaction force chamber 53. A stopper 56 is attached to the intermediate support member 55 to prevent the reaction force plunger 52 from falling off. The space 57 formed around the stub shaft 3
Communicate with the tank passage 58.

Now, when the steering wheel is operated, the stub shaft 3 rotates against the pressing force of the reaction force plunger 52. Reaction force plunger 52 at this time
Force acts on the steering wheel as a steering reaction force.

The second embodiment shown in FIGS. 4 and 5 uses a sliding valve V'as the control valve CV. The structure of the steering device using this sliding valve V'is as follows. That is,
The pinion 5 that meshes with the rack 7 is the pinion shaft 6
It is supported by the casing 63 through bearings 61 and 62 which are formed integrally with the pinion 0 and are located in front of and behind the pinion 5. In the bearings 61 and 62, the outer race 78 of the bearings 61 and 62 is inserted into an elliptical play hole 77 having a long axis parallel to the rack 7, and the pinion shaft 60 is located within the play hole 77. It is formed to be displaced. However, although the pinion shaft 60 is connected to a steering wheel (not shown), a mechanism for absorbing the lateral displacement is provided in the middle thereof.

On the other hand, the spool valve 64 is arranged with respect to the casing 63 in a direction orthogonal to the pinion shaft 60. The spool 65 and the sleeve 66 of the spool valve 64 have a pump-side passage 67,
A tank-side passage 68 and passages 69 and 70 communicating with a power cylinder (not shown) are provided. Then, when the spool 65 moves from the neutral position in the figure to the left or right,
The pressure oil supply direction to the power cylinder is switched according to the moving direction. Spool valve 64 and pinion shaft 6
Between 0 and 0, the parallel movement at the time of steering of the pinion shaft 60 is enlarged to increase the spool 65 of the spool valve 64.
Is provided with a drive lever 71. The drive lever 71 has a ring portion 72 that fits into the pinion shaft 60, and a support pin 73 and a drive pin 74 are projectingly provided at symmetrical positions passing through the center of the ring portion 72. The support pin 73 has a support hole 75 of the casing 63. In addition, the drive pins 74 are inserted into the pin holes 76 of the spool 65, respectively, and move in an arc shape around the support pins 75 as the pinion shaft 60 is displaced left and right.
The spool valve 64 is switched by.

When the steering wheel is operated to rotate the pinion shaft 60 in either direction, the rack 7 does not move due to the ground resistance on the tire side. However, bearing 6
Since the outer races 78 of 1 and 62 roll in the play hole 77, the pinion 5 rolls on the rack 7 if the rack 7 does not move. When the pinion 5 rolls on the rack 7 in this way, the pinion shaft 60 also moves parallel to the rack 7 within the play hole 77. At this time, the drive lever 71
Swings in the displacement direction of the pinion 5 with the portion of the support pin 73 that fits into the support hole 75 as a fulcrum,
The drive pin 74 is swung along with the swinging motion of the. In this way, the spool valve 60 is switched and moved.

Hydraulic reaction chambers 79 at both ends of the spool 65
Communicates with the hydraulic reaction force chamber port 81 via the passage 80. The hydraulic reaction force chamber port 81 communicates with the flow priority valve 43 and the pressure control valve 47, like the rotary valve V of the first embodiment. The hydraulic reaction force chamber 53
A reaction force plunger 52 ′ that slides on the sleeve 66 is provided between the and the spool 65. Since the pressure acts on the hydraulic reaction force chamber 79 as in the first embodiment, the reaction force plunger 52 'pushes the spool 65 from both ends of the spool 65. When the steering wheel is operated, the spool 65 moves via the drive lever 71 against the pressing force of the reaction force plunger 52 '. Thus, the force that the spool 65 receives against the pressing force of the reaction force plunger 52 'acts on the steering wheel as a steering reaction force.

As can be seen from FIG. 5, in this embodiment,
Equal pressure is applied to the hydraulic reaction chambers 79 at both ends of the spool 65. Although not shown, a spring has been used in the prior art at a position corresponding to the hydraulic reaction chamber 79 in order to apply a reaction force. This means that when the control valve CV is assembled, the spring load is applied to the spool 6
The spring load and the neutral position of the spool 65 must be finely adjusted so that the spool 65 is in the neutral position when the spool 65 is acted on from both ends. In the present invention, since the spring is not used for the reaction force, it is not necessary to finely adjust the spring and the spool 65 as described above, and the productivity is improved.

[0042]

Since the flow rate supplied to the power cylinder is controlled by the pressure control valve and the flow priority valve controlled by the controller, for example, it is not necessary to process the inside of the control valve in a complicated manner, and the productivity is improved. Got well. Further, since the pressure acting on the hydraulic reaction chamber is also controlled by the pressure control valve according to the power assist force, for example, when a sliding valve is used, it is necessary to use a spring for acting the reaction force. Is gone. Therefore, it is not necessary to make a delicate adjustment to match the set load of the spring with the neutral position of the control valve in a state where this spring force is applied, and productivity is improved.

[Brief description of drawings]

FIG. 1 is a circuit diagram of the present invention.

FIG. 2 is a sectional view of the first embodiment.

FIG. 3 is a sectional view taken along line III-III in FIG.

FIG. 4 is a sectional view of a second embodiment.

5 is a sectional view taken along line VV of FIG.

FIG. 6 is a cross-sectional view using a conventional rotary valve.

FIG. 7 is a circuit diagram specifically showing a conventional rotary valve.

FIG. 8 is an enlarged view of a conventional chamfered portion.

FIG. 9 is a graph showing a relationship between a conventional valve operating angle and an opening area of a passage communicating with a tank.

FIG. 10 is a graph showing the relationship between the pressure of a conventional power cylinder and the valve operating angle.

FIG. 11 is a conventional equivalent circuit.

FIG. 12 is a circuit diagram specifically showing a conventional rotary valve.

FIG. 13 is an enlarged cross-sectional view of a control unit of a conventional rotary valve.

FIG. 14 is a graph showing the relationship between the pressure of a conventional power cylinder and the valve operating angle.

FIG. 15 is a conventional equivalent circuit diagram.

[Explanation of symbols]

 2 Pinion shaft 3 Stub shaft 5 Pinion 7 Rack CV Control valve C Power cylinder T Tank 43 Flow priority valve 45 Control flow side 46 Excess flow side 47 Pressure control valve 48 Hydraulic reaction part 49 Controller 50 Pressure sensor

Claims (1)

[Claims] 1. A stub shaft that rotates integrally with a steering wheel, a rod of a steering system, a pinion shaft having a pinion that meshes with the rod, a control valve that switches according to an operating angle of the steering wheel, and In a steering force control device for a power steering comprising a power cylinder that operates according to a switching position of a control valve and a controller that receives an external signal such as a vehicle speed, a pressure control valve controlled by the controller, A hydraulic reaction chamber that is controlled by a pressure control valve and applies a hydraulic reaction force to the steering wheel,
A flow priority valve that changes the outflow rate of the control flow side and the surplus flow side according to the differential pressure before and after the throttling provided inside is provided, and the control flow side of this flow priority valve and the pressure control valve are connected. At the same time, the surplus flow side of the flow priority valve is connected via a control valve, and a pressure sensor for detecting a change in the load pressure of the power cylinder is provided between the flow priority valve and the power cylinder. The controller controls the pressure control valve to change the differential pressure across the flow priority valve according to the change in the load pressure of the power cylinder,
A steering force control device for a power steering, characterized by controlling a supply flow rate to a power cylinder and correspondingly controlling a power assist force of the power cylinder and a pressure acting in a hydraulic reaction force chamber.