JPS61110671A - Power steering device - Google Patents

Abstract

PURPOSE:To make steering wheel load variable so smoothly according to a car speed, by controlling movement of a spool valve of a control mechanism with a hydraulic reaction mechanism which operates with differential pressure between a fixed throttle and a variable throttle mechanism installed in the point midway in a bypass passage. CONSTITUTION:In time of driving at low speed, this slow running is detected by a sensor 53, operating a solenoid 51a with a signal, and a throttle of a variable throttle valve is enlarged, increasing the discharge of a hydraulic fluid to some extent. There fore, differential pressure between the variable throttle valve and a fixed throttle mechanism 50 is made smaller whereby pressure of the hydraulic fluid led into reaction chambers 31 and 32 from a branch passage 52 is also made smaller. Here, when a stub shaft 29 is rotated with a steering wheel 43, at first a sector shaft receives resis tance of wheels, and a piston 1 and a worm shaft 8 both are immovable whereby there is produced relative turning displacement between these shafts 8 and 29. Accord ingly, when a pin 30b is turned round, either of pistons 23 and 24 moves to the right or left so that a shaft 20 rotates and a spool valve 12 is slidingly moved by a pin 30a, whereby the hydraulic fluid is selectively fed or drained to or from each of operat ing chambers 3 and 4 so that steerage is assisted and a steering wheel is nimbly steera ble.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a power steering device.

BACKGROUND ART In general, a hydraulic control mechanism selectively controls the supply and discharge of hydraulic oil to two working chambers in a cylinder separated by a piston to assist the steering operation of a steering member connected to the piston. In a power steering system, sufficient steering assisting force is required when the lights and IF vehicles are running at low speeds or when the vehicle is stationary. From the standpoint of achieving the same steering stability, a steering assist chip is not so necessary. In other words, it is preferable that the steering wheel load is light when the vehicle is running at low speed or when the vehicle is stationary, and that the steering wheel load is heavy when the vehicle is running at high speed.

Therefore, in response to this request, the present applicant has proposed, for example, a power steering device & described in % Tsumugi No. 56-178663. A hydraulic control mechanism is configured in this power steering device at a position opposite to a hydraulic control mechanism for selectively supplying and discharging hydraulic oil to two working chambers in a cylinder separated by a piston. #I is provided with a hydraulic reaction force mechanism that regulates the movement of the spool in two stages depending on the vehicle speed.

Problems to be Solved by the Invention However, in the above-mentioned power steering device, the hydraulic reaction force mechanism controls the movement of the spool constituting the hydraulic control mechanism by dividing it into two stages. Therefore, after the switching point M, the oil pressure of the hydraulic oil supplied to and discharged from the two working chambers via the spool suddenly changes, giving the operator a sense of discomfort.

Means for Solving the Problems In order to solve this difficult conventional problem, the present invention includes the following:
Hydraulic oil discharged from the pump? , in the middle of a bypass path that branches from a supply path for supplying two working wJ amounts separated from each other to the piston and is connected to a hydraulic oil discharge path, from the supply path to the bypass path. A fixed diaphragm mechanism that allows limited upward movement of hydraulic oil, and a variable diaphragm mechanism that changes the opening area of the bypass path in accordance with vehicle speed on the lower side of the fixed diaphragm mechanism are provided, and the hydraulic reaction force mechanism is provided. A hydraulic reaction force mechanism that brakes the movement of the spool valve to be retracted according to the differential pressure between the hydraulic pressure generated in the fixed throttle mechanism and the hydraulic pressure generated in the variable throttle mechanism;
It is.

Operation: The power control system according to the present invention, which has such a configuration, is equipped with a fixed throttle mechanism and a fixed throttle mechanism installed in the middle of the bypass path branching from the hydraulic oil supply path, and an opening surface of the bypass path according to the vehicle speed. The hydraulic pressure generated in relation to the variable throttle mechanism b is guided to the full hydraulic reaction force mechanism, and this hydraulic reaction force mechanism controls the hydraulic control mechanism t-
The movement of the spool valve to be purchased is designed to be gradually braked, so that the steering wheel load vi1'' can be smoothly increased or decreased according to the vehicle speed.

Embodiments of the present invention will be described below based on the drawings.

Figure 1 shows the power steering device according to the present invention.
FIG. 2 is a sectional view taken along line 1-1 in FIG. 1.

1st ej! J and 2, two working chambers 3.4 are separated in the cylinder 2 by the piston 1,
The piston 1 is connected to a sector shaft 40 which is a steering member that drives a steering link. Said cylinder 2
A housing 5 whose one end is sealed has a supply hole 6 and a discharge hole 7 for supplying and discharging hydraulic oil discharged from the pump P to the two working chambers 3.4. A worm shaft 8, which is an output member that provides steering power to the wheels, is rotatably housed through a bearing 9. The piston 1 is attached to one end of the worm shaft 8.
are screwed together via a ball screw 41.

Further, a stub shaft 29 connected to a steering wheel 43 is connected to the other end of the worm shaft 8 via a torsion bar 42 having a rotatable mechanism.

Furthermore, there is a bottom on the other end side of this worm shaft 8, ^11
A hydraulic control @ #10 is provided to selectively supply and discharge hydraulic oil to the two working chambers 3 and 4 to fully assist the steering operation of the sector shaft 40. This hydraulic system 1 mechanism 1
(l) The construction shown in FIG. 12, and is formed within the valve-shaped recess 11 on the outer periphery of the spool valve 12 at a predetermined distance I14 in the axial direction.
Three valve chambers 13°14, 15 are formed by four lands.
is formed. Of these, the valve chambers 13, 14H located on both sides communicate with the annular groove 5& formed between the housing 5 and the worm shaft 8 via supply ports 16, 17'. Among these, All lft: Valve chamber 13
In addition, an oil passage 18'9r through 11. is provided in one working chamber 3. At the same time, oil is connected to the m1 chamber 14 and the other working chamber 4.
i! It communicates via 19 ports. In addition, the front valve chamber I (.

Among 14 and 15, two stub shaft bins 30 are connected to the valve chamber 15 located in the center of the valve chamber 15 and communicated with the discharge hole 7 through 44 oil passages, and are provided on the stub shaft 29.
When the spool valve 12 installed in the stub shaft bin 301 of -J among a and 30b is slid in the axial direction within the valve-shaped recess 11, the valve chamber 15 (= the opposing valve chamber 13 or the valve chamber At the same time, the bacterial passage area of the supply ports 16 and 17 relative to the valve chambers 13 and 14 increases or decreases.

On the other hand, on the other end side of the worm shaft 8, as shown in FIG.
#20 is provided. This hydraulic reaction machine vI20 is
a control cylinder 21 fixed to the worm shaft 8;
A sealing plate 22 that closes both end openings of this cylinder 21
, 22, two pistons 23, 24 fitted into the control cylinder 21, and elastically mounted between these pistons 23, 24 and each of the sealing plates 22, 22. It is composed of springs 25 and 26. The position of the pistons 23 and 24 is regulated by stopper rings 27 and 28 fixed to the cylinder 21, which control the biasing force of the H springs 25 and 261. The other stub shaft pin 30b of the stub shaft pins 3Qa and 30b is inserted between the pistons 23 and 24 without any play, and like the spool valve 21, the stub shaft pin 30b is inserted between the pistons 23 and 24 with no play. The rotation of the shaft 4 allows one of the two pistons 24 to be pushed against the spring force of the spring 25 or 26. Both pistons 23, 24 move inside the control cylinder 21.
The reaction force chambers 31 and 32 separated by 24 communicate with the oil passage blades through through holes 33 and 34 opened thereto, and an annular oil passage 37t formed between the worm shaft 8 and the housing 5. ing. Note that a stub shaft insertion chamber 45 formed between the two pistons 23 and 24 is in communication with the hydraulic oil discharge hole 7 through an oil passage 46.

Friend, a supply path 47 is provided between the pump P and the two working chambers 3.4 for supplying hydraulic oil discharged from the pump P to each working chamber 3.4. Branched from the supply path 47 and connected to the hydraulic oil discharge path 48, ? In the middle of the C bypass passage 49, there is a fixed throttle mechanism that allows a limited flow of hydraulic fluid from the supply passage 47 to the bypass passage 49, and a throttle valve that moves forward depending on the vehicle speed on the Shimonoseki side between the fixed throttle mechanisms. A variable diaphragm mechanism 51 for changing the aperture surface of the dC bypass passage 49 is provided respectively. Set rr'rc
A branch passage 52 communicating with the oil passage is also provided. The # hydraulic reaction force machine @20 is adapted to be braked in accordance with the hydraulic pressure generated between the fixed throttle mechanism and the variable throttle mechanism 51. The solenoid 51 & constituting the variable diaphragm 151 is controlled based on the vehicle speed signal and the steering wheel charge selection signal from the longitudinal sensor 53 and the steering wheel load select switch 54, and is operated by the slave controller 550 control output. It's becoming a sea urchin.

Next, the operation of the power steering headpiece according to the first embodiment having this unique configuration will be explained.

First, a case where the vehicle is running at a low speed will be described.

In this case, the vehicle speed sensor 53 detects the low speed running condition, and the controller 55 uses the detected vehicle speed signal to operate the solenoid 511 to increase the throttle tt of the variable throttle valve 51b forming the variable throttle 51. (To) Increase the excess area), and increase the discharge il of the hydraulic oil that passes through the variable throttle valve 51b and goes to the tank T. Then, fixed wringer 11!
Since the hydraulic pressure generated between the control cylinder 50 and the variable throttle mechanism 51 is small, the reaction force chambers 31 in the control cylinder 21 are routed from the branch passage 52 through the oil passage 38, the elliptical oil passage 37, and the through holes 33 and 34. , 32.

Under this situation, when the stub shaft 29'lr is moved clockwise or counterclockwise once by the operating force of the steering wheel 43, the warp shaft 8 is also rotated via the torsion bar 42. However, at the beginning of the rotation, the 7-ohm shaft 40 is receiving ground resistance from the four wheels via the steering link, so the piston remains stationary against the 9-ohm shaft 8. Therefore, a relative rotational displacement occurs between the worm shaft 8 and the stub shaft 4. Accordingly, the stub shaft bins 3Qa and 30kl provided on the stub shaft 4 are rotated clockwise or 'fc.
#"j tries to rotate counterclockwise. In this case, since the pressure in the reaction force chambers 3 and 32 is small, each of the pistons 23 and 240 can be easily moved. Therefore, the stub of external force When the shaft pin 30b rotates clockwise or counterclockwise, it (: accordingly, each piston 2
The spring force of one of the springs 25 and 26 is applied to either one of the springs 3 and 24 to move to the right or to the left. Therefore, the stub shaft 29 and each piston 23
, 24 to rotate in a predetermined direction without being hindered. Therefore, the hydraulic control machine $110'k by one stub shaft bin 30&! spool valve 12
The inside of the cell storage part 11 is rotated and slid in a predetermined direction, and the hydraulic oil from the pump P is selectively supplied and discharged to each working chamber 3.4. Therefore, the differential pressure between these working chambers 3 and 4 causes the piston 1 to move to the right or to the left in the cylinder 2, thereby assisting the steering operation of the sector shaft 40. Therefore, light steering operation is possible.

Next, the vehicle shifts from a low-speed driving state to a high-speed driving state f
Case C will be explained.

In this case, does the vehicle speed sensor 53 indicate that the state has shifted from a low-speed driving state to a high-speed driving state? The controller 55 or solenoid 5HL detects and responds to the corresponding medium speed signal.
is activated, the throttle amount of the variable throttle valve 51b is completely reduced, and the discharge I of the hydraulic oil flowing to the tank T through the variable throttle valve 51b is suppressed. Then, between the fixed diaphragm mechanism and the variable diaphragm M
51, the hydraulic pressure generated between the branch path 5 and
2, the pressure of the hydraulic oil introduced into each of the reaction force chambers 31 and 32 increases, and the pressure increases to the pressure of the reaction force chambers 31 and 32.

Under these circumstances, when the steering wheel 43 is rotated counterclockwise (twice) by the operating force of the steering wheel 43, the pressure inside each of the reaction force chambers 31 and 32 increases. Each piston 23 is manipulated by the pressure of its friend Meko.
, 24 are blocked in the right direction, fC, and left direction, so that the rotational force nM is transmitted to the worm shaft 8. Therefore, it is possible to ensure steering stability during high-speed running, similar to that of a normal steering system with one manual gear connection.

Next, a case will be described in which the vehicle is in the middle of transitioning from a low-speed running state to a high-speed running state.

In this case, the own speed sensor 53 detects that the vehicle is transitioning from the low speed driving state η to the high speed driving state,
In addition, the throttle amount of the variable throttle valve 51b gradually decreases, and the oil pressure generated between the fixed throttle mechanism and the variable throttle mechanism 51 gradually increases, and accordingly, each reaction force chamber 31
, 32 also gradually increases. Therefore, the rotation of the stub shaft bin 30b is gradually braked by the pressure, and the handle load can be smoothly increased. Therefore, the driver can enjoy a natural steering sensation.

In addition,! ! In the above embodiment, the present invention was applied to a recirculating type gj force steering V; using a warm shirt as an output member, but for example, The present invention can also be applied to a rack, and, and pinion type power steering device that uses a pinion shaft.

Effects of the Invention It is clear from the above explanation that if this invention is implemented, a hydraulic control mechanism that operates in accordance with the hydraulic pressure generated between the fixed throttle mechanism and the variable throttle mechanism will be installed in the middle of the bypass path. This hydraulic reaction force mechanism is designed to brake the movement of the spool valve that constitutes the hydraulic control mechanism, so the handle load on the steered wheels can be smoothly increased or decreased according to the vehicle speed. You can enjoy a comfortable steering feel.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view including a block diagram showing an embodiment of the power steering device according to the present invention, and FIG.
FIG. 2 is a cross-sectional view showing the force steering device. DESCRIPTION OF SYMBOLS 1... Piston, 2... Cylinder, 3, 4... Working chamber, 8... Worm shaft (output member), 10...
...Hydraulic reaction force mechanism, 12...Spool valve, 20...
Hydraulic reaction force mechanism, 29... stub shaft (input member)
, 40... sector shaft (steering member), 43...
Steering wheel, 47... Supply path, Induction... Discharge path, 49...
・Bypass omitted, bu)...Fixed diaphragm mechanism, 51...6
f variable diaphragm mechanism, P...pump. 2 people outside

Claims (1)

[Claims] (1) When a relative rotational displacement occurs between the input member driven by the operating force of the steering wheel, the output member that applies the steering force to the wheel, and the input member and the output member, the piston separates the input member and the output member. A power steering device comprising: a hydraulic control mechanism that selectively controls the supply and discharge of hydraulic oil to two working chambers in a cylinder configured to assist the steering operation of a steering member connected to the piston; A bypass passage branching from a supply passage for supplying discharged hydraulic oil to the two working chambers and connected to a hydraulic oil discharge passage is provided in the middle of the bypass passage, in which hydraulic oil flows from the supply passage to the bypass passage. A fixed throttle mechanism that allows limited flow and a variable throttle mechanism that changes the opening area of the bypass passage in accordance with the vehicle speed downstream of the fixed throttle mechanism are provided, and a spool valve that constitutes the hydraulic control mechanism is provided. A power steering device comprising: a hydraulic reaction force mechanism that brakes movement of the fixed throttle mechanism and the variable throttle mechanism according to hydraulic pressure generated between the fixed throttle mechanism and the variable throttle mechanism.