JPH0834361A - Power steering device - Google Patents

Abstract

PURPOSE:To provide an inexpensive vehicle speed responding type power steering device which conducts the variable control of operation pressure to a power cylinder in response to a vehicle speed or the like and can conduct the variable control of assist power. CONSTITUTION:This device is equipped with a rotary type control valve CV that connects a pump P and a tank T selectively to power cylinder right and left chambers CR, CL. Their right and left branching-off passages possess first and second variable throttles 1R, 1L, 2L, 2R that constitute pairs of right and left and conduct opening/ closing control by steering operation. Right and left output side passages 15, 14 from the respective branching-off passages between these variable throttles are connected to the cylinder right and left chambers CR, CL. A bypass passage 18 that connects the right and left branching-off passages to each other is provided separately from the right and left output side passages 15, 14 that run to a power cyinder from the passage portions between both variable throttles. On this bypass passage 18, third variable throttles 3R, 3L that constitute a pair of right and left and are controlled openingly/closingly following steering operation, and a variable throttle valve 4 to be opened/closed in response to other conditions than the steering angle of vehicle speed or the like, are provided in series.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention controls the power assisting force (steering assisting force) according to various vehicle driving conditions such as vehicle speed and steering speed so as to control the vehicle traveling state and steering operation (steering). The present invention relates to a power steering device capable of performing appropriate steering force control according to the magnitude of the load at the time.

[0002]

2. Description of the Related Art For example, in a power steering device that obtains a power assisting force for reducing a steering wheel operating force (steering force) of an automobile, steering force control according to a traveling speed (vehicle speed) of a vehicle can be performed. Is desired. In other words, it is necessary to control the steering force so that the steering wheel can have a sense of rigidity during high-speed traveling while ensuring a stable steering feel while the vehicle is stopped or traveling at low speed. Has become.

For this reason, a flow control type power steering device using a flow control valve is known as a vehicle speed sensitive power steering device. In other words, this type of device uses a variable throttle valve that responds to the vehicle speed at high speed, in addition to the flow control valve function of limiting the pressure oil flow rate to a fixed amount in a pump that is rotationally driven by the engine of an automobile. By reducing the supply flow rate, the generated pressure is reduced and the power assist force in the power cylinder is reduced.
As a result, the steering force was controlled to be heavy.

However, in such a flow rate control type device, since the flow rate of the feed flow from the pump is adjusted only in accordance with the vehicle speed, the control range of the steering force is relatively narrow and the required steering force is required. It was hard to say that I could control it. Further, in such a flow control type device,
There was also an unavoidable problem of poor followability when abrupt steering was performed at high speeds.

Further, as a vehicle speed sensitive power steering device, a vehicle speed response is provided by a reaction force piston for selectively restraining or turning the steering input and output shafts according to the magnitude of reaction force hydraulic pressure. A type using a hydraulic reaction force device is also known. In other words, when the vehicle is stopped or running at low speed, the reaction force oil pressure is minimized to enable a light steering operation, and at the time of high speed running, the reaction force oil pressure is increased to give the steering wheel a sense of rigidity, which improves stability during straight running. The steering force control is performed so as to secure the steering force.
Various structures have been proposed including 1-105273 and JP-A-61-232466.

However, even in such a hydraulic reaction force control type device, for its operation, a reaction force pressure control valve for obtaining a hydraulic reaction force according to the vehicle speed, and a reaction force between the input and output shafts are provided. It is necessary to provide a piston and a reaction force receiving part facing this,
The number of parts is large, the structure is likely to be complicated, and the cost is high, which is a disadvantage. Further, in such a conventional device, friction in the hydraulic reaction device portion often causes a problem in operation performance.

Therefore, as a vehicle speed sensitive type power steering device of this type, a new system is demanded which is low in cost and can secure a steering force control range in practice. In order to meet such a request, Japanese Patent Laid-Open No. 2-1
As disclosed in Japanese Patent No. 75467, in addition to a variable throttle valve controlled by a vehicle speed, a variable throttle controlled so that an opening degree becomes small when a relative angular displacement between an input shaft and an output shaft becomes large. In addition, the variable throttle valve and the variable throttle control the partial flow rate to the bypass passage connecting the supply passage from the pump to the control valve and the return passage to the tank from the control valve to control the steering. The flow rate supplied to the power cylinder at the time is ensured.

According to this structure, the variable throttle valve whose opening is controlled according to the vehicle speed controls the partial flow rate to the tank side, and the variable throttle provided in the bypass passage has the handle operation amount. When the steering wheel is operated, for example, when the steering wheel is operated during middle- and high-speed traveling, the flow rate through the bypass passage is restricted regardless of the opening degree of the variable throttle valve. As a result, the supply flow rate to the power cylinder can be secured.

Therefore, in such a conventional device,
Even when the opening of the variable throttle valve is large, such as when driving at medium or high speeds, the opening of the variable throttle can be reduced in conjunction with the steering wheel operation, so the flow rate discharged from the bypass passage is reduced to supply to the power cylinder. Securing the flow rate, solving the problem of poor responsiveness due to insufficient flow rate as in the past,
The steering force control according to the traveling condition can be optimized.

[0010]

However, according to the conventional vehicle speed-sensitive power steering apparatus improved as described above, a passage for bypassing the supply passage on the upstream side of the control valve and the return passage on the downstream side is provided. In this structure, a variable throttle valve that responds to the vehicle speed and a variable throttle that operates in conjunction with the steering angle are separately provided, and the number of parts is large, the structure is complicated, and the cost is high. It is hoped that some measures will be taken to eliminate all such points.

Particularly, in such a vehicle speed sensitive type power steering apparatus, the response and the followability at the time of steering at high speed are ensured, and the influence of friction such as the hydraulic reaction mechanism is small. Also, the axial length of the steering body including the control valve can be reduced,
Moreover, it is desired to take some kind of consideration so that it is possible to meet demands such as practically securing the steering force control range at low cost.

The present invention has been made in view of the above circumstances, and improves the structure of the entire apparatus including the control valve and combines it with a variable throttle valve that responds to the vehicle speed and the like to improve the power. It is possible to variably control the pressure acting on the cylinder to a required state by changing the vehicle speed, and further, the load variation such as the increase of the steering angle during steering, the steering speed, etc., and it is possible to variably and appropriately control the assist force. The purpose of the present invention is to obtain a suitable power steering device by using it as a vehicle speed sensitive type which can be realized, the steering force control range can be practically secured, and the cost is low.

[0013]

In order to meet such a demand, the power steering apparatus according to the present invention is provided with a pair of left and right first and second members which are controlled to open and close according to a steering operation.
A control valve for selectively switching and controlling the passage between the pump, the tank and the power cylinder left and right chambers, which is constituted by a fluid pressure bridge circuit with left and right branch passages having a variable throttle of A bypass passage connecting the left and right branch passages separately from the left and right output passages from the first and second variable throttles on the left and right branch passages of the control valve to the left and right chambers of the power cylinder. And a pair of left and right third variable throttles that are controlled to open and close in accordance with the steering operation, and a variable throttle that is controlled to open and close according to conditions other than the steering angle (for example, vehicle speed) in the bypass passage. The valve is provided in series.

Further, the power steering apparatus according to the present invention is one of a pair of left and right third variable throttles provided in series with a variable throttle valve of a vehicle speed responsive type or the like on a bypass passage, and is associated with a steering operation. The third variable throttle, which operates toward the closing side, is placed on the side of the branch passage, which becomes the fluid pressure supply side to one chamber of the power cylinder due to the high pressure state due to the steering operation, and the downstream side thereof. One of the third variable diaphragms, which operates on the open side in response to the steering operation, is arranged on the side.

Further, in the power steering device according to the present invention, the respective sliding contact surfaces communicate with the fluid pressure inlet port from the pump, the return port to the tank, the power cylinder left, the left and right output ports to the right chamber. A plurality of passage grooves forming a fluid pressure bridge circuit are formed at predetermined intervals in the circumferential direction, and a rotary control valve including a rotor and a sleeve that are relatively rotatably combined is provided. Between the passage grooves communicating with the return port to the tank of the rotor and the sleeve that constitute the control valve, the left and right passage grooves where the fluid pressure reaching the left and right output ports is introduced through the communication port, and these left, Adjacent to the right passage groove in the circumferential direction, it is selectively communicated by relative rotational displacement of the rotor and sleeve, and responds to conditions other than the steering angle. Left communication port that communicates with the communication passage variable throttle valve to be closed control is bypass passage is provided is opened, it is provided with a and a right connecting groove.

Further, in the power steering apparatus according to the present invention, in the rotary control valve, the first variable throttle is provided between the passage groove on the inlet port side, the left and right passage grooves on the output port side, and the left on the output port side. A second variable throttle is formed between the right passage groove and the passage grooves on the left and right return port sides, and the left and right communication ports are opened, and the left and right communication ports are opened. A variable throttle valve is formed between the left and right connecting grooves to form a third variable throttle, and the opening and closing of which is controlled according to conditions other than the steering angle in the middle of the connecting passage connecting the left and right connecting ports. It is provided.

[0017]

According to the present invention, the fluid pressure from the pump is returned to the tank side through the left and right branch passages of the fluid pressure bridge circuit constituting the control valve when the steering is not performed. Further, when the steering wheel is steered to either side, either the left side or the right side of the first and second variable throttles of the fluid pressure bridge circuit operates to the closing side, the opening becomes small and the other operates to the opening side. However, either the left or right passage is connected to one of the left and right chambers of the power cylinder to supply the fluid pressure, and the other chamber is connected to the tank side and serves as the return side.

When steered during low speed traveling, the variable throttle valve of the vehicle speed sensitive type or the like on the bypass passage communicating between the cylinder chambers is closed, so that the supply side cylinder chamber in the power cylinder is closed. The opening degree of communication between the return side cylinder chamber and the return side cylinder chamber is small, and the pressure cylinder from the pump is supplied to the supply side cylinder chamber through the fluid pressure bridge circuit by the control valve, and the power cylinder is activated to achieve the required pressure. The assist power of is obtained.

Further, when steered during high-speed traveling, the vehicle speed-sensitive variable throttle valve on the bypass passage communicating between both cylinder chambers is controlled to the open side state, and the third variable valve connected in series therewith is controlled. With the opening / closing control based on the steering angle of the throttle, the supply side (high pressure side) cylinder chamber and the recirculation side (low pressure side) cylinder chamber of the power cylinder are brought into communication with each other so that part of the pressure oil from the pump can be bypassed. This makes it possible to control the amount of pressure oil supplied to the supply-side cylinder chamber via the fluid pressure bridge circuit by the control valve to an appropriate amount, reduce the operating pressure of the power cylinder, and reduce the assist force by the power cylinder. Therefore, it is possible to give a suitable feeling to the steering operation.

[0020]

1 to 4 show an embodiment in which a power steering device according to the present invention is used as a vehicle speed-sensitive type. In these figures, first, the outline of the hydraulic circuit in the vehicle speed sensitive type power steering apparatus generally designated by reference numeral 10 will be described with reference to FIG. 11
Control valve CV for switching and controlling pressure oil fed via the steering wheel by steering operation by a steering wheel
Through the power cylinder (indicated by P / C in the figure), which is the device actuator, to the left and right chambers CL and CR, and to recirculate to the tank T.

Reference numeral 11 in the figure denotes a supply passage from the pump P to the hydraulic bridge circuit of the control valve CV, 1
Reference numerals 2 and 13 are left and right branch passages forming a bridge circuit in the control valve CV, and 14 and 15 are left of the power cylinder P / C, left and right branch passages 12 and 1 to the right chamber.
Left and right cylinder passages as left and right output passages from 3 and 16 are return passages from the bridge circuit of the control valve CV to the tank T.

Further, the left and right branch passages 12 and 13 forming the hydraulic bridge circuit of the control valve CV described above.
As is well known, the first variable apertures 1R and 1L and the second variable apertures 2L and 2L that are controlled to open and close in accordance with the steering operation.
Rs are provided facing each other. And these first,
From the left and right branch passages 12, 13 between the second variable throttles 1R, 2L and 1L, 2R to the left and right cylinder passages 14, 15
Is drawn out to appropriately supply or recirculate hydraulic pressure to the left and right chambers CL and CR of the power cylinder.

Such a power steering device 10
In the control valve CV, the pressure oil from the pump P passes through the passages 12 and 1 to the left and right chambers CR and CL of the power cylinder P / C in accordance with the steering direction and steering angle of the steering wheel.
3 is controlled to be switched so that either one of the chambers C
It is well known that the power assisting force for assisting the steering force can be obtained by feeding R and CL through the passages 14 and 15 and connecting the other chamber to the tank T through the passages 15 and 14 as well. The detailed description is omitted here.

That is, the power steering device 10
Is equipped with a control valve CV by a hydraulic bridge circuit that is switched and controlled according to the steering operation to selectively connect the pump P and the tank T to the left and right chambers CL and CR of the power cylinder. The control valve CV is a steering valve. The first and second pairs of left and right, which are controlled to open and close so as to control the supply of pressure oil to the left and right chambers CL and CR of the cylinder in accordance with the operation.
The left and right branch passages 12 and 13 having the variable throttles 1R, 1L, 2L and 2R, and the cylinders from between the first and second variable throttles 1R, 2L, 1L and 2R in the left and right branch passages 12 and 13. Left and right chamber passages 1 to the left and right chambers CL and CR
It is constituted by 4, 15.

Further, according to the present invention, in the above-described power steering device 10, the control valve C
Apart from the left and right cylinder passages 14 and 15 which reach the power cylinder P / C from the passage portion between the first and second variable throttles 1R, 2L, 1L and 2R at V, the left and right branch passages 12 and 1 are provided.
A bypass passage 18 (18a, 18b) connecting between the three is provided, and a pair of left and right third variable throttles 3L, which are controlled to open / close in accordance with the steering operation, are provided in the bypass passage 18.
3R and a characteristic other than the steering angle, in this embodiment, a vehicle speed responsive variable throttle valve 4 that is controlled to open and close in response to the vehicle speed is provided in series.

Here, in this embodiment, the bypass passage 1
The variable throttle valve 4, which is controlled to open and close in response to a vehicle speed that is a condition other than the steering angle on the vehicle 8, is provided between a pair of left and right third variable throttles 3L and 3R.

Furthermore, according to the invention, the bypass passage 1
Of the pair of left and right third variable apertures 3L and 3R that are provided in series on the above 8, one third variable aperture 3R that operates toward the closing side in response to the steering operation is associated with the steering operation. Is placed on the side of the branch passage 13 on the fluid pressure supply side to the one chamber CR of the power cylinder, and on the downstream side thereof, one of the third passages is operated toward the open side in accordance with the steering operation.
The variable diaphragm 3L is arranged.

In other words, the pair of left and right third variable throttles 3L and 3R are brought into a high pressure state along with the steering operation on the bypass passage 18 to supply the fluid pressure to the one chamber CR of the power cylinder. From the side of the branch passage 13 that is the side, either the left or right third variable diaphragm 3R that operates to the closing side in response to the steering operation, and the other third variable diaphragm 3R that operates to the opening side in response to the steering operation. The variable diaphragms 3L are arranged in series in this order.

According to such a configuration, the pressure oil from the pump P when the steering wheel is not steered is either the left or right branch passage 12 of the hydraulic bridge circuit forming the control valve CV.
When it is turned back to the tank T side via 13 and steered to either side, either the left side or the right side of the first and second variable throttles 1L, 2L, 1R, 2R of the hydraulic bridge circuit is operated to the closing side. When the opening degree becomes small and the other operates toward the open side, one of the left and right branch passages 12 and 13 is connected to one of the left and right chambers CL and CR of the power cylinder to supply pressure oil. The other chamber is connected to the tank T side and serves as a return side.

When steered during low-speed traveling, the vehicle speed-sensitive variable throttle valve 4 on the bypass passage 18 communicating between the cylinder chambers CL and CR, as is apparent from the characteristics shown in FIG. Because it is on the closed side,
The communication opening between the supply side cylinder chamber CR or CL and the return side cylinder chamber CL or CR in the power cylinder P / C is small, and the pressure oil from the pump P passes through the fluid pressure bridge circuit by the control valve CV to the supply side. By supplying substantially the entire amount to the cylinder chamber CR or CL, the power cylinder P / C is operated and a required assist force is obtained.

Further, during steering during high speed running,
Bypass passage 18 that communicates between both cylinder chambers CL and CR
The vehicle speed-sensitive variable throttle valve 4 on (18a, 18b) is controlled to the open state, and the power cylinder P is controlled in accordance with the opening / closing control by the steering angle of the third variable throttles 3L, 3R connected in series. / C supply side (high pressure side) cylinder chamber CR
Or CL and recirculation side (low pressure side) cylinder chamber CL or C
A part of the pressure oil from the pump P can be bypassed by making it in a communication state with R, whereby the supply amount supplied to the supply side cylinder chamber CR or CL via the fluid pressure bridge circuit by the control valve CV is appropriate. Therefore, the operating pressure of the power cylinder P / C can be reduced, the assisting force of the power cylinder P / C can be reduced, and the steering operation can be given an appropriate feel.

Here, the vehicle speed-sensitive variable throttle valve 4 described above is used.
By controlling the opening area with respect to the vehicle speed as shown in FIG. 4, for example, the communication between the cylinder left and right chambers CR and CL via the bypass passage 18 is controlled to a desired state, and as a result, during steering. Power cylinder P /
The supply amount of the pressure oil to the supply side cylinder chamber CR or CL of C is controlled to an appropriate amount, and a force corresponding to the vehicle speed can be obtained as the power assist force.

Further, in the above-described structure, the bypass passage 18 is provided in comparison with the conventional general power steering apparatus 10.
And the vehicle speed responsive variable throttle valve 4 in series on the passage 18.
The required assist force control can be performed simply by adding the steering angle responsive third variable throttles 3L and 3R, so that low cost and high reliability can be achieved, and an inexpensive vehicle speed sensitive power steering system. Can be obtained. Further, the hydraulic reaction force mechanism part used in the conventional hydraulic reaction force control type power steering is unnecessary, there is no adverse effect due to the friction, and the space in the input shaft direction of the device can be reduced. It is possible to obtain the power steering device 10.

The details of the rotary type control valve CV to which the present invention is applied will now be described with reference to FIGS. 1 and 2. Reference numeral 31 in the drawings denotes an input shaft (not shown) connected to the steering handle side. The rotor 32 provided integrally with the stub shaft) and the sleeve 32 provided integrally with the output shaft (pinion shaft) on the steered wheel side (not shown) in a state of being fitted to the outer circumference of the rotor 31 are well-known. It is installed inside a valve housing (not shown) after being combined with each other by a torsion bar or the like so as to be relatively rotatable.

Reference numeral 33 denotes a plurality of (two in this example) passage grooves formed on the outer peripheral portion of the rotor 31 at predetermined intervals in the circumferential direction. These passage grooves 33, 33 are centered on the axial center of the rotor 31. The inlet ports 33a (denoted by P) are formed opposite to each other at the symmetrical positions and are connected to the oil pump P, which is a fluid pressure generation source, via the supply passage 11.
Further, reference numerals 34 and 35 denote a plurality of (in this example, four in total, two) passage grooves formed at predetermined intervals on both sides in the circumferential direction of the passage groove 33, and these passage grooves 34, 35 are provided.
Is connected to a return passage 16 formed in the rotor 31 in the centripetal direction and reaching the oil tank T through the internal space of the rotor 31 (denoted by T).
Is open.

36 and 37 are return ports 34a and 35a on both sides of the entrance port 33a in the inner peripheral portion of the sleeve 32.
Is a passage groove of a plurality of lines (in this example, two lines in total, four lines in total) formed so as to communicate with the passage groove 33 and the passage groove 34 or 35.
7 is the left and right cylinder chambers CL and C of the power cylinder P / C
Left and right output ports 36a, 37a (denoted by CL, CR) connected to the output passages 14, 15 leading to R are opened.

Then, these output side passage grooves 36, 37
And the first groove that is opened / closed due to relative rotational displacement of the rotor 31 and the sleeve 32 between the inlet side passage groove 33.
Variable apertures 1R, 1L of the output side passage groove 3 are formed.
6, 37 and the return-side passage grooves 34, 35,
Second variable stops 2L and 2R are formed.

Reference numerals 40 and 41 denote outer peripheral portions of the rotor 31. The passage groove 33, the passage grooves 36 and 37 on both sides thereof, and the return passage between two pairs of passage switching portions formed by the passage grooves 34 and 35 on both sides thereof. The left and right passage grooves 40, 41 formed adjacently to the grooves 34, 35 in the circumferential direction.
Is configured so that the hydraulic pressure reaching the left and right output ports 36a, 37a is introduced via the communication ports 40a, 41a. In addition, these left and right passage grooves 40, 41
Are in communication with the passages 14 and 15 via the passages 42 and 43.

Further, 44 and 45 are these left and right passage grooves 4
The rotor 31 and the sleeve 3 are adjacent to each other in the circumferential direction of 0 and 41.
Left selectively communicated by two relative rotational displacements,
In the right connecting groove, the left and right connecting grooves 44, 45 are provided with the vehicle speed responsive variable throttle valve 5 and communicate with the communication passages 18a, 18b serving as the bypass passages.
a and 45a are opened.

Here, the left and right communication ports 40a, 41
Left and right passage grooves 40 and 41 and communication port 4 where a is opened
Third variable throttles 3L, 3R are formed between the left and right connecting grooves 44, 45 in which 4a, 45a are opened, and a connecting passage 18 connecting the left and right connecting ports 44a, 45a.
a, 18b (18) A vehicle speed responsive variable throttle valve 4 which is controlled to open and close in response to conditions other than the steering angle, in particular, the vehicle speed.
Is provided.

In this embodiment, the passage groove, the connection groove and each port having the same function are formed at positions symmetrical with respect to the axial center of the rotor 31 and the sleeve 32, that is, at positions radially balanced, and the workability is improved. Also, consideration is given to cost.

In such a valve structure, when a relative rotational displacement occurs between the rotor 31 and the sleeve 32 due to the steering operation, the first, second and third variable throttles respectively respond to the steering angle. By controlling the opening / closing to a predetermined opening degree and changing the communication state of each groove, the flow path of the hydraulic circuit is switched.

Here, in the first, second, and third variable throttles which are variable throttles that respond to the steering load, the first and second variable throttles 1L, 1R, 2R, 2L function as the control valve CV. And the third variable throttles 3R, 3L on the side of the bypass passage 18 are similarly opened and closed to switch the flow paths. And the connecting passage 18 of this bypass passage 18
By opening and closing the vehicle speed responsive variable throttle valve 4 on the a and 18b in accordance with the vehicle speed, the bypass amount through the bypass passage 18 is controlled, and the power cylinder P / C is controlled.
The amount of pressure oil supplied to the supply side of is controlled, and a required force can be obtained as an assist force.

In the structure of this embodiment, the bridge circuit which constitutes the control valve CV, the bypass passage 18, the vehicle speed responsive variable throttle valve 4, and the steering angle responsive third variable throttles 3L and 3R are provided. Is integrally incorporated in a rotary valve portion including the rotor 31 and the sleeve 32, and the required assist force control can be achieved simply by adding the bypass passage 18 and the vehicle speed responsive variable throttle valve 4 to the conventional valve. Therefore, the vehicle speed sensitive power steering device 10 can be obtained at a low cost and with high reliability and at a low cost.

In particular, according to such a structure, the variable throttles 3L, 3R, etc. forming the bypass passage 18 can be attached to the rotary type control valve CV by simple groove processing, so that the structure is structurally improved. Is also easy to operate,
The function as a vehicle speed sensitive type can be exhibited, the size of the device in the input shaft direction can be reduced, the size can be reduced, and the cost can be great.

Here, the above-mentioned third variable diaphragms 3L, 3
The left and right passage grooves 40, 4 are made so that the opening / closing characteristics at R, especially the characteristics of the closing operation angle are made larger than those of other variable throttles.
1, the left and right connection grooves 44, 45 are formed at appropriate positions, formation widths, etc., so that the passage on the pressure oil return side can be secured with a predetermined opening, and the steering force according to the steering angle and the vehicle speed can be secured. We are trying to make the control more effective.

The present invention is not limited to the structure of the above-described embodiment, but the shape and structure of each part such as the vehicle speed sensitive power steering device 10, the fluid pressure bridge circuit of the control valve CV thereof, the bypass passage 18 structure and the like. Needless to say, can be appropriately modified and changed.

For example, in the above-mentioned embodiment, the first,
The second and third variable diaphragms 1L, 1R, 2L, 2R, 3L,
The throttle opening characteristic with respect to the steering torque of 3R and the throttle opening characteristic with respect to the vehicle speed in the vehicle speed responsive variable throttle valve 4 may be appropriately modified in accordance with changes in setting conditions based on requirements of applicable equipment and configurations of respective parts. To be

Further, in the above-described embodiment, the variable throttle valve 4 provided in series on the bypass passage 18 in series with the third variable throttles 3L and 3R controls opening / closing according to the vehicle speed which is a condition other than the steering angle. However, the present invention is not limited to this. For example, as control factors other than the steering angle for controlling the opening / closing of the variable throttle valve 4, there are steering speed, steering angular velocity, lateral G, etc., which may be appropriately adopted as necessary.

Further, in the above-mentioned embodiment, detailed illustration and description of the main body portion in which the control valve CV of the power steering device is incorporated, the power cylinder P / C, etc. are omitted, but if a conventionally well-known structure is adopted. Good.

[0051]

As described above, according to the power steering system of the present invention, the power steering bridge circuit is constituted by the left and right branch passages having the first and second variable throttles, which are paired left and right. A control valve for selectively switching and controlling the passage between the pump and the tank and the left and right chambers of the power cylinder is provided, and between the first and second variable throttles on the left and right branch passages of this control valve. ,
In addition to the left and right output passages that reach the left and right chambers of the power cylinder, a bypass passage that connects the left and right branch passages is provided,
In addition, in this bypass passage, a pair of left and right third variable throttles that are controlled to be opened / closed in accordance with the steering operation and a variable throttle valve that is controlled to be opened / closed in accordance with conditions other than the steering angle, for example, the vehicle speed, are connected in series. Since it is provided in the above configuration, various excellent effects listed below can be obtained despite the simple and inexpensive configuration.

That is, according to the present invention, when the vehicle is traveling at a low speed, the variable throttle valve of the vehicle speed responsive type or the like in the bypass passage is set to the closed side, and the third variable throttle is controlled to open / close by the steering angle. It is possible to appropriately control the steering force by sending almost the entire amount of pressure oil from the engine to the supply side cylinder chamber of the power cylinder to obtain a required assist force.

Further, during steering during high speed traveling, the variable throttle valve of the vehicle speed responsive type in the bypass passage is set to the open side, and the third variable throttle is opened / closed to a required opening degree according to the steering angle. By controlling, the supply amount from the pump to the supply side cylinder chamber of the power cylinder is controlled so as to reduce the assisting force, and by making the steering handle heavy, it is possible to give the driver a suitable feeling of response. With
It becomes possible to secure steering followability during high-speed traveling.

Further, according to the present invention, a bypass passage having a variable throttle valve of a vehicle speed responsive type or a third variable throttle of a steering angle responsive type is added to a conventional general power steering device. Since required assist force control can be performed, low cost and high reliability can be achieved, and an inexpensive vehicle speed sensitive power steering can be obtained. Further, according to the present invention, the hydraulic reaction force mechanism portion used in the conventional hydraulic reaction force control type power steering is unnecessary, the adverse effect due to the friction is small, and the space in the input shaft direction of the device is reduced. It is possible to obtain a vehicle speed-sensitive power steering capable of

In particular, according to the power steering device of the present invention, the steering operation of the pair of left and right third variable throttles provided in series on the bypass passage with the variable throttle valve of the vehicle speed responsive type or the like is performed. One of the 3rd ones that moves to the closing side with
The variable throttle is placed on the side of the branch passage, which becomes the fluid pressure supply side to one chamber of the power cylinder due to the high pressure state due to the steering operation, and is opened on the downstream side with the steering operation. It is configured such that the one third variable diaphragm that operates in the above manner is arranged, and the above-described operational effect can be further exerted.

Further, according to the power steering apparatus of the present invention, a plurality of articles are connected to the fluid pressure inlet port from the pump, the return port to the tank, the power cylinder left, the left and right output ports to the right chamber. Is provided with a rotary control valve including a rotor and a sleeve that are rotatably displaceable and are formed at predetermined intervals in the circumferential direction, and between the passage groove that communicates with the return port of the rotor and the sleeve to the left, Fluid pressure reaching the right output port is introduced through the communication port, and is selectively communicated with the left and right passage grooves, which are adjacent in the circumferential direction of these left and right passage grooves, by the relative rotational displacement of the rotor and the sleeve. In addition, a variable throttle valve that is controlled to open and close in response to conditions other than the steering angle is provided, and a communication port that communicates with a communication passage that serves as a bypass passage is opened on the left, Since there is provided a connecting groove, despite the simple structure, it is possible to further exhibit the actions and effects described above.

In particular, according to such a configuration, the bypass passage, etc., which characterizes the present invention, can be attached to the rotary type control valve by simple grooving or the like, so that both structurally and operationally. It is simple and can exert a function as a vehicle speed-sensitive type, and the size of the device in the input shaft direction can be reduced, downsizing can be achieved, and the cost is also great.

Further, according to the power steering device of the present invention, the first variable throttle is provided between the passage groove on the inlet port side and the left and right passage grooves on the output port side in the rotary control valve. The second variable throttle is formed between the left and right passage grooves of the left side and the left and right return port side passage grooves, and the left and right passage ports and the communication port are opened. A variable throttle whose third variable throttle is formed between the left and right connecting grooves, which are opened, and which is controlled to be opened and closed according to conditions other than the steering angle in the middle of a connecting passage connecting the left and right connecting ports. By providing the valve, it is possible to further exert the effect.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing an example of a case where a power steering device according to the present invention is applied to a vehicle speed sensitive type, and a main structure of a rotary type control valve to which the present invention is applied.

FIG. 2 is a schematic cross-sectional view when steering is performed in the rotary type control valve in FIG.

FIG. 3 is a schematic configuration diagram for explaining a configuration of a main part of a power steering device according to the present invention.

FIG. 4 is a characteristic diagram showing a change in opening area with respect to a vehicle speed in a vehicle speed responsive variable throttle valve used in the device of the present invention.

[Explanation of symbols]

1L, 1R ... First variable throttle, 2L, 2R ... Second variable throttle, 3L, 3R ... Third variable throttle, 4 ... Vehicle speed-responsive variable throttle valve, 10 ... Vehicle speed-sensitive power steering device, 11 ... Supply passages, 12, 13 ... Left and right branch passages constituting fluid pressure bridge circuit, 14, 15 ... Left, right cylinder passages (left and right output passages), 16 ... Return passages, 18 ...
Bypass passage, 18a, 18b ... communication passage, 31 ... rotor, 32 ... sleeve, 33, 34, 35 ... passage groove, 33
a ... incoming port, 34a, 35a ... return port, 36,
37 ... Passage groove, 36a, 37a ... Output port, 40, 4
1 ... Left and right passage grooves, 40a, 41a ... Communication port, 4
2, 43 ... connecting passage, 44, 45 ... left, right connecting groove, 44
a, 45a ... Communication port, P ... Pump, T ... Tank, C
V ... Rotary control valve, P / C ... Power cylinder, CL, CR ... Cylinder left, right chamber.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tetsuya Koike 2-11-6, Shinmei-cho, Higashimatsuyama-shi, Saitama Automotive Equipment Co., Ltd. Matsuyama Factory

Claims (6)

[Claims] 1. A pump constituted by a fluid pressure bridge circuit with a variable throttle whose opening and closing is controlled according to a steering operation,
A control valve for selectively controlling the passage between the tank and the left and right chambers of the power cylinder is provided. The control valve has a pair of left and right first and second variable throttles. In a power steering device including a right branch passage and left and right output passages extending between first and second variable throttles in the left and right branch passages to a cylinder left and a right chamber, Provided on the left and right branch passages is a bypass passage connecting the left and right branch passages separately from the left and right output passages extending from the first and second variable throttles to the power cylinder left and right chambers. Further, in this bypass passage, a pair of left and right third variable throttles that are controlled to be opened / closed in accordance with the steering operation and a variable throttle valve that is controlled to be opened / closed in accordance with conditions other than the steering angle are provided in series. Characterized by That the power steering system. 2. The power steering apparatus according to claim 1, wherein the variable throttle valve that is controlled to open and close on the bypass passage according to a condition other than a steering angle is provided between a pair of left and right third variable throttles. A power steering device characterized by being provided. 3. The power steering apparatus according to claim 1, wherein among the pair of left and right third variable throttles provided in series on the bypass passage, the third variable throttle is closed on the closing side in accordance with the steering operation. One of the third variable throttles, which operates, is placed on the side of the branch passage, which becomes the fluid pressure supply side to one chamber of the power cylinder due to the high pressure state due to the steering operation, and is steered to the downstream side. A power steering device characterized in that one third variable diaphragm which is operated on the opening side in accordance with an operation is arranged. 4. The power steering apparatus according to claim 1, 2 or 3, wherein the variable throttle valve that is controlled to open and close on the bypass passage according to conditions other than the steering angle is a vehicle speed responsive variable throttle valve. A power steering device characterized in that 5. The power steering apparatus according to claim 1, claim 2, claim 3, or claim 4, wherein a fluid pressure inlet port from a pump is provided on each sliding contact surface,
By communicating with the return port to the tank, the power cylinder left, the left and right output ports to the right chamber, a plurality of passage grooves that form a fluid pressure bridge circuit are formed at predetermined intervals in the circumferential direction and A rotary control valve with a rotor and a sleeve that are rotatably combined with each other is provided, and the left and right output ports are connected between the passage grooves communicating with the return port to the tank of the rotor and the sleeve that constitute this control valve. The fluid pressure to reach the left and right passage grooves is introduced through the communication port, and the left and right passage grooves are adjacent to each other in the circumferential direction and selectively communicated by the relative rotational displacement of the rotor and the sleeve and the steering angle. The left and right connections are provided with a variable throttle valve that is controlled to open and close in response to conditions other than the above, and a communication port that communicates with the communication passage that serves as a bypass passage is opened. A power steering device having a continuous groove. 6. The power steering apparatus according to claim 5, wherein the first variable throttle is provided between the passage groove on the inlet port side and the left and right passage grooves on the output port side and the left and right passage grooves on the output port side. A second variable throttle is formed between the left and right return port side passage grooves, and the left and right communication ports are opened left, the right passage groove and communication port are opened left, A third variable throttle is formed between it and the right connecting groove, and a variable throttle valve that is controlled to open and close according to conditions other than the steering angle is provided in the middle of the communication passage that connects the left and right communication ports. A power steering device characterized in that