JPH0115570Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a power steering device for a vehicle that applies a hydraulic steering reaction force in stages according to vehicle speed.

In order to reduce the steering force of the vehicle,
In the case of a power steering device that uses hydraulic pressure to power assist during steering, hydraulic reaction force is fed back to the input shaft in order to prevent the steering wheel from becoming too light due to the power assist and to give the driver an appropriate operating feel. are doing.

By the way, in order to maintain steering stability while driving at high speeds, when a high vehicle speed is detected separately from the hydraulic steering reaction force, for example, the flow rate of pressure oil sent to the power cylinder is reduced to reduce the power assist force. There is something I did.

The steering sensation provided by the hydraulic reaction force is primarily to prevent the steering wheel from being turned too far, and therefore the reaction force becomes stronger in proportion to the rotational speed of the steering wheel. This does not mean that a large reaction force is obtained, and the steering reaction force is applied regardless of the vehicle speed.

Therefore, in order to obtain stability at high speeds, it is necessary to separately provide the above-mentioned flow rate control means, and in this case, the structure becomes unavoidably complicated.

On the other hand, British Patent No. 810716 discloses a device that increases the steering reaction force according to the vehicle speed. High-speed stability is ensured by changing the steering reaction force at low and medium speeds and the steering reaction force at high vehicle speeds without any special provision.

However, in order to apply the valve switching reaction force as a steering reaction force, this device requires a hydraulic source whose hydraulic pressure is controlled according to the vehicle speed, and a plurality of auxiliary pistons that operate in response to this hydraulic pressure. The drawback was that it was mechanically quite complex.

On the other hand, the applicant had previously filed Utility Application No. 56-128799.
No. (Refer to Utility Model Application No. 58-33369), a hydraulic switching valve that is switched by a signal from the vehicle speed detection means is provided, and the hydraulic pressure generated by steering operation is transferred to the spool of the control valve via this hydraulic switching valve. We are proposing a power steering system that has a simplified structure by applying the same amount of force to the valve and increasing the valve reaction force only during high-speed steering operations.

However, since this device rapidly changes the steering reaction force when transitioning from low to medium speeds to high vehicle speeds, the degree of change is large and is not favorable for the driver in terms of steering sensation.

The present invention was developed to solve this problem, and includes a hydraulic switching valve that switches in multiple stages based on signals from the vehicle speed detection means. It is an object of the present invention to provide a power steering device that gradually increases valve reaction force in stages during high-speed steering operation by applying the hydraulic pressure generated accordingly.

Hereinafter, embodiments of the present invention will be described based on the drawings.

What is shown in FIGS. 1 and 2 is an embodiment applied to a rack-and-pinion type power steering device, in which 1 is a rack connected to a steering link (tie rod etc. not shown), 2 is a pinion, 3 is a spool valve, and 4 is a main body housing these.

A pinion 2 that meshes with the rack 1 is formed integrally with a pinion shaft 5 and is supported by the main body 4 via bearings 6 and 7 provided before and after the pinion 2. The outer race 9 of these bearings 6 and 7 is inserted into an oval long hole 8 whose long axis is parallel to the rack 1, and is formed so that the pinion shaft 5 can be displaced by a predetermined distance left and right. There is.

Next, the spool valve 3 is arranged in a direction perpendicular to the pinion shaft 5 and is slidably housed in the valve housing 16, so that the displacement of the pinion shaft 5 coincides with the sliding direction of the spool valve 3, and the spool valve 3 is driven. The spool valve 3 is switched and operated by the lever 10.

The lever 10 has a ring portion 1 that fits into the pinion shaft 5.
A support pin 12 and a drive pin 13 are protruded at symmetrical positions passing through the center of the valve 1, the support pin 12 is inserted into the support hole 14 of the main body 4, the drive pin 13 is inserted into the pin hole 15 of the spool valve 3, The spool valve 3 is switched by a drive pin 13 that moves in an arc shape around a support pin 12 as the pinion shaft 5 is displaced from side to side.

The spool valve 3 has a valve housing 16
The valve housing 16 is provided with annular grooves 17 to 19 that form pressure oil passages between the valve housing 16 and the annular grooves 17 to 19 to connect the hydraulic chambers A and B of the power cylinder 20 to conduits 21a and 21b. Operating ports 22a, 22b, a pump port P, a tank port T, etc. are formed which selectively communicate with the pump side or the tank side via the spool valve 3.
When the cylinder moves from the neutral position shown in the figure to the right or left, the direction in which the pressure oil is switched to the power cylinder 20 changes depending on the direction of movement. Note that 23 is a neutral spring that urges the spool valve 3 to a neutral position.

Further, pistons 25 and 26 are fixed to an extension shaft 24 fixed to one end of the spool valve 3, and the pistons 25 and 26 are inserted into cylinder holes 29 and 30 defined by partition walls 27 and 28 in the valve housing 16.
and two sets of reaction force chambers 31a and 31 on both sides thereof.
b, and 32a and 32b are formed.

On the other hand, a hydraulic switching valve 33 is provided that selectively sends pressure oil to the two sets of reaction force chambers 31a to 32b. The spool 34 of this hydraulic switching valve 33 is driven by a solenoid 35, and the solenoid 35 receives a signal from a vehicle speed detecting means 36 to set a predetermined high vehicle speed and super high speed (or medium high speed and high speed) through an amplification circuit 37. Excitation current is supplied to the two stages at least in the high vehicle speed range of the two stages.

The outer periphery of the spool 34 has an annular groove 39 through which a pressure oil passage is formed between the spool 34 and the valve housing 38.
42, and the valve housing 38 also has four inlet ports 43-46 and an outlet port 4.
7 to 50 are formed.

Among the inlet ports 43 to 46, 43 and 45 are connected to the conduit 21a through conduits 51a and 51a', and
4 and 46 are connected to the pipe 21b via pipes 51b and 51b'.
communicate with. On the other hand, among the outlet ports 47 to 50, 47 and 49 are connected to the reaction force chambers 31a and 32a via conduits 52a and 53a, and 48 and 50 are connected to the conduit 5.
It communicates with reaction force chambers 31b and 32b via 2b and 53b, respectively.

Then, the spool 34 moves one step to the left in the drawing to connect the reaction force chambers 31a or 31b, or moves two steps to the left to connect the reaction force chambers 31a and 32a or 31b and 31b.
2b and the operating port 22a or 22b. Note that 54 is a return spring that urges the spool 34 to a non-operating position.

Next, the effect will be explained.

Now, when the pinion shaft 5 is rotated clockwise by operating a handle (not shown), the resistance of the rack 1 connected to the steering link is large, so the elongated hole 8 allows the pinion shaft 5 to be rotated along the rack 1 in this rotation direction. The pinion 2 is displaced by that amount.

At this time, the drive lever 10 is moved by the drive pin 13 that moves in an arc shape around the support pin 12.
Switch the spool valve 3 to the right. With this switching of the spool valve 3, hydraulic oil from the pump port P is supplied to one oil chamber A of the power cylinder 20 through the pipe 21a, and the rack 1 is driven in the rotational direction of the pinion 2. be.

By the way, at this time, the neutral spring 23 is compressed and acts as a resistance against the movement of the spool valve 3, which causes a steering reaction force to act on the steering wheel side. 35 is not excited, the spool 34 is displaced to the right by the action of the return spring 54, and the reaction force chambers 31a, 31b and 3
2a and 32b are pipes 52a, 52b and 53a
53b, no acting force other than the spring reaction force of the neutral spring 23 is generated. In other words, the steering reaction force in the low and medium speed range can be kept small.

On the other hand, when the solenoid 35 is excited based on the signal from the vehicle speed detection means 36 in a high speed range,
The spool 34 of the hydraulic switching valve 33 is displaced one step to the left, causing the inlet port 43 and outlet port 47 to communicate with each other.

Therefore, in this state, the high pressure operating port 2
Hydraulic oil 2a flows through pipe 21a → 51a → inlet port 43 → outlet port 47 → pipe 52a → reaction force chamber 31
a, and the piston 25 receives a pushing force in the left direction.

Since this pressing force acts to return the spool valve 3, which is about to switch to the right, to the neutral direction, the steering reaction force on the handlebar side increases accordingly.

In this way, a relatively larger steering reaction force is generated in the high vehicle speed range than in the low speed range, improving the stability of high-speed steering.

When the vehicle speed further increases to a super high speed range, the excitation current of the solenoid 35 is increased based on a signal from the vehicle speed detection means 36 that detects this, and the spool 34 of the hydraulic switching valve 33 is moved one step further to the left. Displaced to. As a result, the inlet port 45 and the outlet port 49 are further interlocked while the inlet port 43 and the outlet port 47 continue to communicate with each other.

Therefore, in this state, the high pressure operating port 2
The hydraulic oil 2a is further supplied in the order of pipe 21a→51a'→inlet port 45→outlet port 49→pipe 53a→reaction force chamber 32a, and the piston 26 also receives a leftward pressing force.

Since this pressing force acts to further return the spool valve 3 to the neutral direction, the steering reaction force on the handle side increases accordingly.

In this way, a relatively larger steering reaction force is generated in the ultra-high speed range than in the high-speed range, improving the stability of ultra-high speed steering.

Note that when the handle is operated to move the spool valve 3 to the left in the opposite direction to the above, two-stage steering reaction forces are similarly generated in the high-speed range and the ultra-high-speed range.

Further, in this embodiment, the reaction force is generated in two stages, but it is clear that the reaction force can be further increased to three or four stages.

FIG. 3 shows an embodiment applied to a booster type power steering device, in which the shifter housing 55
, a valve housing 16 and a booster 56. The cylinder hole 57 of the shifter housing 55 is connected to the shifter chamber 59 by a wall 58 which is clamped and fixed to the valve housing 16, and partition walls 27 and 28 which are fixed to the cylinder hole 57 by a snap spring. Force chambers 31, 32
It is defined as.

A sleeve 60 is slidably housed in the shifter chamber 59, and a hanger 61 and two seats 62, 62 are installed inside the sleeve 60, and between these two seats 62, 62 a ball stud 6 is inserted.
The ball portion 63a of No. 3 is held in between.

The externally protruding tip of the ball stud 63 is connected to the tip of a pitman arm 66 of a steering gear 65 via a rod 64, so that, for example, when the handle 67 is turned to the left, the steering gear 65, the pitman arm 6
6. The sleeve 60 is moved to the left with respect to the shifter housing 55 via the rod 64 and the ball stud 63.

The left end of the booster 56 is closed by a cap 68 which is held between the valve housing 16 and a piston 69 that is slidably housed inside the booster 56. Booster 56 at 69
The interior is defined into left and right pressure chambers A and B.

Then, the shifter housing 55 and the booster 56
A valve hole 71 of the control valve 70 is formed inside the valve housing 16 which is held between the valve housing 16 and the spool valve 3 is housed in the valve hole 71 of the control valve 70. This spool valve 3 has a space inside, and a spool bolt 7 passes through this space.
2 is connected integrally with a step formed in the middle of the spool bolt 72 and a nut at the right end via a clamping plate 73 fitted to the spool bolt 72 facing both ends of the spool valve 3. There is.

The left side of this spool bolt 72 is the wall 5
8. It extends to the shifter chamber 59 through the reaction force chambers 31, 32 and the partition walls 27, 28, and the large diameter portion 72a at the left end thereof is fitted into the hanger 61 in the sleeve 60, and the rotation of the handle 67 When the sleeve 60 is moved in the left-right direction with respect to the shifter housing 55 during operation, the spool valve 3 can be moved left and right together with the sleeve 60 to perform a switching operation.

On the other hand, the pistons 25 and 26 are located at the portions of the spool bolt 72 that face the two reaction force chambers 31 and 32.
are fixedly installed, and the reaction force chambers 31, 32 are divided into two sets of reaction force chambers 31a, 31b and 3 by the pistons 25, 26.
2a and 32b.

Two annular grooves 74 and 75 are formed on the outer peripheral surface of the spool valve 3, and three annular grooves 76 to 78 are formed on the inner peripheral surface of the valve hole 71. , each actuating port 2 formed in the valve housing 16.
2a, 22b to the left and right pressure chambers B, A of the booster 56, while the central annular groove 77 of the valve hole 71 communicates to a hydraulic pump (not shown) via a passage 79, and the left and right annular grooves grooves 76, 78
is connected to a tank (not shown) via a passage 90, and as the handle 67 is rotated, the spool valve 3 is displaced left and right via the sleeve 60 and the spool bolt 72 to switch the passage.
Pressure oil from a hydraulic pump can be selectively guided to pressure chambers A and B of 6.

On the other hand, inside the valve housing 16, a hydraulic switching valve 33 is provided that selectively sends pressure oil to the two sets of reaction force chambers 31a to 32b. This hydraulic switching valve 33 is similar to the one shown in FIG. 2, and an internal spool (not shown) is driven by a solenoid 35.
An excitation current is supplied to two stages in a predetermined high-speed range and an ultra-high-speed range via the amplification circuit 37 based on a signal from the high-speed range.

This hydraulic switching valve 33 and two sets of reaction force chambers 31a, 3
1b, 32a, 32b are linked by pipes 52a, 52b and 53a, 53b, respectively, as in FIG. 2, and the hydraulic switching valve 33 operates in the same manner as in FIG. Since pressurized oil is supplied to each of the reaction force chambers, two stages of steering reaction force are generated, improving steering stability and feeling.

As explained above, according to the present invention, during steering at high speeds and ultra-high speeds, hydraulic pressure is applied in stages to counter the displacement of the control valve spool, increasing the steering reaction force to at least two stages. This improves steering stability and steering feel at high speeds, while using the hydraulic pressure supplied from the control valve's operating port to generate reaction force, which simplifies the structure without requiring a hydraulic power source. Since reaction force hydraulic pressure is not generated except during steering, there is no need to worry about malfunctions.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of the present invention, FIG. 2 is an explanatory view including a cross-sectional view taken along the line -- in FIG. 1, and FIG. 3 is a cross-sectional view showing another embodiment of the present invention. 1... Rack, 2... Pinion, 3... Spool valve, 5... Pinion shaft, 10... Drive lever, 16... Valve housing, 20... Power cylinder, 22a, 22b... Operating port, 24...
...Extension shaft, 25, 26...Piston, 31a, 3
1b, 32a, 32b...Reaction force chamber, 33...Hydraulic switching valve, 34...Spool, 35...Solenoid, 36...Vehicle speed detection means, 38...Valve housing, 43-46...Inlet port, 47 ~50
...Exit port, 55...Shifter housing, 5
6...Booster, 72...Spool bolt.

Claims (1)

[Scope of utility model registration request] In a power steering device comprising a spool-type control valve that switches and operates based on input rotation from a steering wheel, the control valve selectively supplies pressurized oil to an output drive unit connected to wheels via the control valve. at least two on the extension shaft of the spool valve.
At least two sets of reaction force chambers are formed on both sides of the piston and expand and contract reciprocally with the displacement of the spool; a vehicle speed detection means for detecting the high speed range of the vehicle in stages; Hydraulic pressure that is originally switched in stages in a high-speed range and selectively guides pressure oil from the operating port of the control valve to one or more of the corresponding reaction chambers among the at least two sets of reaction chambers. A power steering device that is equipped with a switching valve and that generates hydraulic pressure in a reaction chamber in stages in response to displacement of a control valve spool in a high-speed range.