JPS63176777A - Oil pressure reaction unit for power steering device - Google Patents

Abstract

PURPOSE:To properly and securely obtain a reactional oil pressure having a required magnitude by controlling a rotary valve by means of a pulse current based on a duty ratio which is sent out of a controller in accordance with the traveling condition of a vehicle. CONSTITUTION:An on/off type rotary valve 30 rotated by an electric motor 30a is provided in an oil pressure passage which can control a reactional oil pressure fed into an oil pressure reaction chamber 25. This rotary valve 30 is provided for controlling the reactional oil pressure. And, this rotary valve 30 is rotated by a pulse current from a controller 32 which sends out an output pulse signal based on a duty ratio corresponding to a vehicle speed and the size of a steering angle. Thereby, the reactional oil pressure feeding passage 31 can be on/off controlled at a high speed by driving the rotary valve.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention provides a hydraulic reaction system for obtaining an appropriate steering force in accordance with running conditions such as the running speed (vehicle speed) and steering angle of a vehicle in a power steering system. Concerning improvements in power devices.

[Conventional technology]

Power steering devices, known as power steering, have been widely installed in various vehicles including small cars in recent years, and their steering assist power reduces the driver's steering effort and enables nimble steering operations. In addition, various configurations have been known that are effective in reducing driver fatigue and the like.

By the way, in this type of power steering device, the operation of the device is appropriately controlled based on various driving conditions such as the steering force and steering angle according to the driver's steering operation, and the traveling speed of the vehicle. , it is desired to have a configuration that can provide steering assist force as needed. In other words, in a vehicle equipped with this type of power steering device, an extremely light steering force can be obtained when performing a steering operation when the vehicle is stopped, so-called stationary, or when driving at low speed. Therefore, it is necessary to have a configuration that can output a large steering assist force. However, on the other hand, when the vehicle is traveling at high speeds, if a large steering assist force is generated as described above when driving at low speeds, the operating force on the steering wheel becomes too light, causing driver anxiety. This leads to problems such as increasing the driver's sense of control, which is not practical in terms of optimizing the driving sense.On the contrary, the steering assist force is reduced to increase the steering wheel's weight to a certain extent, that is, the steering force. There is a need for a structure that increases the stability of the vehicle when traveling in a straight line.

For this reason, hydraulic reaction force devices that can control the stiffness (steering reaction force) of the steering wheel when the vehicle is running at high or low speeds have been generally adopted by applying a strong steering reaction force to the steering wheel. For example, JP-A-59-1
As shown in Publication No. 84288, etc., a spool valve that is slidably operated by an electromagnetic solenoid is provided in the middle of the hydraulic passage connecting the pump and the flow path switching valve, and the amount of restriction is changed by the movement of this spool valve. , there is known a structure in which reaction oil pressure is controlled in accordance with vehicle speed and the like and is sent to a hydraulic reaction force chamber. In such a conventional structure, by controlling the reaction force hydraulic pressure to the hydraulic reaction force chamber, it has become possible to control the steering force to some extent in accordance with the driving conditions of the vehicle as described above.

[Problem that the invention seeks to solve]

However, in the conventional device described above, the spool valve that controls the reaction oil pressure is proportionally controlled in an analog manner using an electromagnetic solenoid, so it is necessary to process the spool valve with high precision by grinding, etc. This not only poses problems in terms of workability, but also has negative effects on spool operation, such as hydraulic flow force (force acting in the axial and tilting directions of the spool), making fine adjustment control difficult. Moreover, in order to reliably perform proportional control of the spool position, the size of the electromagnetic solenoid is increased, leading to problems such as increased cost.

Furthermore, since the electromagnetic solenoid is configured to perform the above-mentioned proportional control, the sliding resistance of the solenoid and the spool valve is large, which poses a problem in terms of responsiveness. In addition, in such conventional devices, there is a constant flow of hydraulic pressure, so there are problems such as a lot of leakage at high pressures and a decrease in operating efficiency, so it is desirable to take some measures with these points in mind. There is.

In particular, what is desired in the above-mentioned hydraulic reaction device is
The reaction hydraulic pressure can be controlled accurately, appropriately, and reliably with a configuration as simple and inexpensive as possible, and the structure and shape of the control system are simple and have excellent workability.Furthermore, appropriate reaction hydraulic control can control vehicle speed and steering. These points must be taken into consideration because it is possible to appropriately control the steering force according to various driving conditions of the vehicle, such as angle, etc., and to obtain an appropriate steering feeling.

[Means for solving problems]

In order to meet the above-mentioned demands, the hydraulic reaction force device of the power steering device according to the present invention is a rotary type as an on-off type rotary valve that controls the reaction hydraulic pressure supplied to the hydraulic reaction chamber. Alternatively, a swing type valve is provided in the hydraulic passage, and each time the hydraulic passage is opened and closed by an output pulse signal with a duty ratio sent from the controller according to the vehicle speed and the magnitude of the steering angle, the valve is driven. This is what I did.

[Effect]

According to the present invention, a rotary valve is rotated or oscillated by a pulse current according to a duty ratio sent from a controller according to the running conditions of the vehicle, and the supply passage to the hydraulic reaction force chamber is controlled to open and close. It is possible to appropriately and reliably obtain a reaction force oil pressure having a required magnitude, thereby enabling appropriate steering force control.

〔Example〕

Hereinafter, the present invention will be explained in detail using embodiments shown in the drawings.

FIG. 1 shows an embodiment of a hydraulic reaction force device for a power steering device according to the present invention. In the figure, what is designated by the symbol l is the power steering main body that constitutes the power steering device. A rotary flow path switching valve 3 that switches and controls the hydraulic circuit is disposed inside the main body 2, and the pressure oil from the oil pump 5 driven by the engine 4 is transferred to the power cylinder 6 that generates the steering assist force. It serves to supply feed to one of the left and right chambers C1 and C2 in response to a steering operation, and to connect the other chamber to the tank 7 side, and its configuration is well known.

Here, to briefly explain the general configuration of the power steering main body 1 described above, the reference numeral 10 in the figure is the steering handle 8.
The input shaft (stub shirt) 11 is connected to the left end side of the input shaft 10 via a torsion bar 12, and has a pinion lla that engages with a rack 13 constituting a steering link mechanism (not shown). The output shaft (pinion shaft) has an output shaft (pinion shaft), and these two shafts to and tt are appropriately rotated in the steering direction. Note that the shaft constituting the power cylinder 6 is integrally connected to the rack 13.

In addition, a body 2 constituting the power steering main body l
A rotary flow path switching valve 3 is installed on both shafts 10 and 11 mentioned above.
A rotor 14 and a sleeve 15 are each provided integrally, and their relative rotational displacements control the flow between the oil pump 5, the oil tank 7, and the left and right cylinder chambers (C1, C2) of the power cylinder 6. It is also well known to perform route switching.

Reference numeral 20 denotes a hydraulic reaction device provided between the rotor 14 and the sleeve 15 that constitute the flow path switching valve 3, and the output shaft 10.11;
A plurality of pawls 22 are held slidably only in the axial direction within a guide hole formed to penetrate in the axial direction in a flange portion 21 provided in A reaction force receiving part 24 having a plurality of engagement recesses 23 having sloped surfaces and provided on the input shaft 1O facing one side of the flange part 21, and a reaction force receiving part 24 formed on the other side of the flange part 21. A hydraulic reaction force chamber 25 is provided, and a person is held in this hydraulic reaction force chamber 25 so as to be slidable on the same axis as the output shaft 10. Press and apply a restraining force according to the reaction oil pressure, output shaft 10゜1
1 and a ring-shaped reaction force piston 26 that acts between the two. In the hydraulic reaction force device 20 having such a configuration, an annular seal member 27 is provided at the end (left end) of the hydraulic reaction chamber 25 opposite to the reaction force piston 26.
It is designed to seal with.

The hydraulic reaction chamber 25 configured as described above is moved in the axial direction within the body 2 during a steering operation in accordance with the reaction oil pressure that is appropriately supplied according to various running conditions of the vehicle such as vehicle speed. When the ring-shaped reaction force piston 26 presses the pawl 22 against the engagement recess 23 side, the required restraint force is obtained by the hydraulic reaction force, and the relative rotational state between the person and the output shaft 10.11 is controlled. The structure is such that appropriate steering force control can be performed by appropriately restraining the steering force and obtaining the necessary steering reaction force.

Now, according to the present invention, a required position in the hydraulic passage (in this embodiment, from the pump 5 to the hydraulic reaction chamber 25
As shown in FIGS. 1 and 6, a rotary valve 30 rotatably driven by an electric motor 30a, for example, is installed in the supply passage 31) as an on-off type rotary valve for reaction hydraulic pressure control. Provided and this rotary valve 30
is rotationally driven by a pulse current from a controller 32 that sends out an output pulse signal with a duty ratio according to the vehicle speed and the magnitude of the steering angle as shown in FIGS. 7(a), (b), and (c). This is characterized in that the reaction oil pressure supply passage 31 can be controlled on/off (opening/closing) in a high speed state. In addition,
In FIG. 1, numeral 33 is a vehicle speed sensor for detecting the vehicle speed based on the rotational speed of the engine 4, and numeral 34 is a steering angle sensor attached to the steering wheel 8 for detecting the driver's steering direction and steering angle. Furthermore, FIG. 6 is a hydraulic circuit diagram simplified from FIG. 1.

Further, the rotary valve 30 described above is shown in FIGS. 2 to 5.
As is clear from the figure, a sleeve 36 is integrally provided within the body 35 via a bottle or the like, and this sleeve 3
The rotor 37 is rotatably supported within the sleeve 36, and the rotor 37 is fixed onto the output shaft 3Ob of the electric motor 30a to be rotationally driven within the sleeve 36. A pump port 38 is provided on the outer periphery of the sleeve 36 and constitutes a supply passage 31 that is bored in a part of the body 35 and reaches the hydraulic reaction chamber 25.
An annular passage groove 36a is formed, and the annular passage groove 36a is connected to a plurality of (four in this embodiment) passage holes 36b extending in a centripetal direction from equidistant positions in the circumferential direction of the sleeve 36. ing. On the other hand, at positions equally distributed in the circumferential direction on the outer periphery of the rotor 37, as shown in FIGS.
As is clear from the figure, a plurality (four) of passage grooves 37a selectively communicating with each of the passage holes 36b are formed from the center in the axial direction to the end opposite to the motor 30a. The end of the passage groove 37a opposite to the motor 30a opens into a space 39a formed by a cover integral 39 connected to the open end of the body 35. Further, this space 39a is connected to the hydraulic reaction chamber 25 via a supply passage 31 by a reaction chamber boat 40 bored in a part of the integral cover 39.

In such a configuration, when the rotor 37 is rotationally driven within the sleeve 36 by the motor 30a, the passage flI37a on the outer circumference is directed toward the sleeve 36 side, as shown in FIGS. 3(a) and 3(b). The supply passage 31 is selectively communicated with and cut off from the passage hole 36b, and thereby the supply passage 31 is controlled to open/close (on/off) at high speed. In this case, if the opening area of the passage hole 36b to the passage groove 37a described above cannot be secured and the required flow rate cannot be supplied, the passage hole 36b is opened to the passage groove 37a of the rotor 37, as shown by the imaginary line in FIG. It is preferable to arrange a necessary number of other passage holes 36c in parallel in the axial direction of the sleeve 36.

Here, in the rotary valve 30 having the above-described configuration, in this embodiment, the positional relationship of the rotor 37 in the rotational direction within the sleeve 36 when the motor 30a is not energized is always kept at a constant position (neutral position). As is clear from FIGS. 2 and 4, a connecting rod 41 is inserted into a cylindrical portion 39b protruding from one side of the cover unit 39 within the space 39a as a return mechanism for returning to the original state. through rotor 37
A movable element 43 connected to the movable member 43 and biased in the centripetal direction by a reaction spring 42 is slidably supported. Note that 44 and 45 are connection pins for rotatably connecting both ends of the connection rod 41 to the rotor 37 and the movable element 43.

Here, what should be noted in this return mechanism is that the connecting rod and the rod 41 urged by the reaction spring 42
As is clear from FIG. 5, the connection position to the rotor 37 side is connected via the connection pin 44 to a position eccentric from the rotor 37 axis 0, and the other end of the connection rod 41 is connected. The axis of the movable element 43 in the sliding direction is shifted laterally from the axis passing through the axis 0 of the rotor 37. This is configured to ensure that a rotational force is applied to the connecting rod 41 by the biasing force of the reaction spring 42, regardless of the state of the relationship with the sleeve 36 when the rotor 37 is de-energized. It is easy to understand that this configuration is necessary in order to ensure the return to the neutral position.

In this case, the neutral position of the rotor 37 with respect to the sleeve 36 can be, for example, (1) a state in which the two are not in communication, (2) a state in which both are in complete communication, and (2) a state in which the opening area of both is narrowed. However, in this embodiment, (2) is adopted.

Further, in FIGS. 1 and 6 described above, the reference numeral 48
is a return path for the reaction oil pressure to the tank 7 side, and an orifice 49 is provided along the way. In this case, the return passage 48 having the orifice 49 may be a leakage passage using clearance between appropriate parts without providing a special passage.

In such a configuration, the rotary valve 3
For the electric motor 30a that drives 0.

7(a), (b),
An intermittent current is supplied as a pulse signal with a rectangular wave having a different duty ratio as shown in FIG. ) The pressure change in the hydraulic passage (31) can be controlled by controlling the time (rotational speed) in the closed (off) state area that is cut off from the off state area, and even if the rotational speed of the rotor 37 is simply changed, (The flow rate does not change and the pressure does not change), thereby applying the required reaction force pressure according to the above-mentioned conditions to the hydraulic reaction force chamber 25, obtaining the required steering reaction force and appropriate steering force control. It's something you get.

In other words, when driving at low speeds or stationary steering when you want to reduce the steering force, the on signal (valve open) period in one cycle of the pulse signal becomes the off signal (valve closed) as shown in Figure (a). It is preferable to set the duty ratio small so that it is smaller than . In this way, the amount of hydraulic pressure sent to the supply passage 31 side flows only little by little, and the average hydraulic pressure Become.

In addition, as shown in the same figure (b), the duty ratio is approximately 1.
: When set to 1, the average oil pressure y becomes medium, and a larger steering reaction force than in the case described above can be obtained and the required steering operation is possible.
Furthermore, as shown in FIG. 2(C), when the duty ratio is increased, the average oil pressure 2 also becomes larger, and as a result, it becomes possible to increase the steering force such as when driving at high speed.

That is, by changing the duty ratio as described above, steering force characteristics as shown by a, b, and c in FIG. 8 can be obtained. Here, a in Figure 1 shows the characteristic curve when no or a small amount of steering reaction force control is carried out, 1 in the figure shows the characteristic curve when control is carried out only according to the vehicle speed, and C in the figure 2 shows characteristic curves when the vehicle speed is 80 km/h and control is performed according to the vehicle speed and steering angle, and the effects thereof can be easily understood.

Furthermore, FIG. 9 is a characteristic diagram showing the magnitude of the duty ratio at each vehicle speed value according to the steering angle, and by performing such control with the controller 32, the steering as shown in FIG. This allows reaction force control to be performed appropriately and reliably.

According to the hydraulic reaction force device 20 according to the present invention that can perform such steering reaction force control, the hydraulic passage (31)
By using a rotary valve 30 that can be controlled to open and close (on/off), the required hydraulic reaction force is obtained, making the structure simpler than when using an electromagnetic solenoid that performs proportional control as in the past. This has advantages such as being excellent in workability and cost, and also being able to achieve overall miniaturization, as well as improving responsiveness and driving efficiency of the device.

In particular, in the configuration using the rotary valve 30 according to the present invention, compared to the conventional case where a spool valve is driven by an electromagnetic solenoid, there is no adverse effect such as flow force due to hydraulic pressure, and the motor 30a etc. This has the advantage that the rotational torque at the drive source can be suppressed to a small level, and the drive source can be made smaller. In addition, with such a rotary valve configuration, compared to a simple reciprocating plunger drive known as an on-off valve, there is no contact when opening and closing, so there are no noise problems. It has the following advantages and its practical effects are great.

Further, according to the present invention, since the motor 30a that drives the rotary valve 30 is configured to be rotationally driven by a signal from the controller 32, the rotor 37
The passage n37a formed in the sleeve 36, the passage hole 3
Even if a machining error or the like occurs in the 6b or the like, by taking this into consideration in advance and inputting it to the controller 32, it can be corrected very easily and reliably. This can be done freely and reliably for each hydraulic reaction device, which has great advantages.

Although the above-mentioned on-off rotary valve 30 can sufficiently control the pressure, there is a problem that the controlled flow rate is small. It is sufficient that the pressure is small and that the pressure can be controlled, and there is no functional problem.

Furthermore, the control in the controller 32 that supplies the control current based on the duty ratio as described above to the rotary valve 30 is performed as schematically shown in FIG. 10, and its basic configuration and operation are, for example, It will be easily understood that this is approximately the same as that disclosed in Japanese Patent Laid-Open Publication No. 81-155059.

Furthermore, various modifications of the hydraulic reaction force device 20 according to the present invention as described below are possible in terms of its circuit configuration.

For example, in the above-mentioned FIG. Instead of the fixed orifice 49, another on/off rotary valve 30
They may also be provided in series.

Furthermore, as a modification thereof, as shown in FIG. 11, an on/off type rotary valve 30 is provided only in the return passage 48, and a fixed orifice 52 is provided in the reaction oil pressure supply passage 31. It will be easily understood that the effect is approximately the same as that of the embodiment described above.

Further, a dedicated oil pump 53 may be used for supplying hydraulic reaction force, and in this case, a circuit configuration as shown in FIGS. 12 and 13 can be considered. Here, in order to operate the hydraulic reaction force in conjunction with pressure fluctuations on the PS side, the first
2 shows a case in which the hydraulic pressure supply path 50 and the reaction hydraulic pressure supply path 31 are communicated with each other by a communication path 54, and a rotary valve 30 of the on-shaft off type is provided in the middle, and the return path 4
8 also shows a configuration in which another on/off type rotary valve 30 is provided. However, it will be clear that this is not necessarily the case, and that the on-off rotary valve 30 on the return side may be replaced by a fixed orifice.

On the other hand, in FIG. 13, a pressure sensor 55 is provided in order to sense the above-mentioned pressure fluctuation on the PS side, and the on/off type provided in the reaction hydraulic pressure supply passage 31 and the return passage 48 is transmitted via the controller 32 using the signal from the pressure sensor 55. The rotary valve 30.30 is configured to control the rotary valve 30.30. In this case, one of the dual on/off rotary valves 30 may be replaced with a fixed orifice.

Furthermore, as shown in FIG. 14, the reaction hydraulic pressure supply passage 31
A reverse valve 57 is provided in the middle of the valve 3, an accumulator 56 is provided, and a sensor 58 detects the reaction oil pressure to the oil pressure reaction chamber 25.
In this case, a return passage 48 may be provided and another on/off type rotary valve 30 may be arranged in parallel in the middle of the return passage 48.

Furthermore, as shown in FIG. 15, two pumps 5.5a may be arranged in parallel and connected through a communication passage 59 having a throttle 59a, or two pumps 5, 5a may be arranged in parallel as shown in FIG. Modifications such as serial connection may also be considered.

Even when these circuit configurations are adopted,
On/off type rotary valve 3 installed in the hydraulic passage
0 makes it possible to introduce the reaction hydraulic pressure at a predetermined pressure into the hydraulic reaction force chamber 25 and obtain the required steering reaction force.

Note that the present invention is not limited to the structure of the embodiments described above, and the shape and structure of each part may be modified or changed as appropriate.
Various modifications can be made to the structure and driving method of the rotary valve (30) for controlling the reaction hydraulic pressure, as well as the control device in the controller 32, etc. For example, in the above-mentioned embodiment, the case where the rotary valve is a rotary type that is connected to and rotationally driven by the electric motor 30a that is a rotational drive source is described, but the present invention is not limited to this, and For example, even if a swing drive source such as a swing solenoid obtained by using a magnet or the like is used to swing the rotor 37 to open and close the hydraulic passage, the same effect as described above can be achieved. It is easy to understand that it is effective.

Furthermore, in the rotary type (oscillating type) valve 30 described above,
As a mechanism for always returning the rotor 37 to a constant positional relationship with respect to the sleeve 36, a configuration in which a connecting rod 41 is combined with a movable element 43 biased by a reaction spring 42 has been illustrated, but the present invention The present invention is not limited to this, and various modifications can be considered, such as using a cam having a polygonal shape such as a rectangular shape, or using a magnet.

Further, in the above-mentioned embodiments, the hydraulic reaction device 20 is of a structure in which the pawl 22 is pressed against the reaction force receiver 23 side by the reaction force piston 26, and the power steering device is of a rack and pinion type. However, the present invention is not limited to this, and it is preferable to appropriately select and use a structure having a conventionally known structure, and various modifications are possible.

〔Effect of the invention〕

As explained above, according to the hydraulic reaction force device for a power steering device according to the present invention, an on/off type rotary valve is used to control the reaction oil pressure to the hydraulic reaction chamber, and This rotary valve is opened and closed (on/off) by a rotation or swing drive source driven by a control current from a controller that sends an output pulse signal with a duty ratio depending on the vehicle speed and steering angle. Although the configuration is simple and inexpensive, the reaction hydraulic pressure can be appropriately and reliably controlled and supplied to the hydraulic reaction chamber according to the vehicle running conditions, and the It is possible to perform steering reaction force control, and the on/off type rotary valve has a simple structure, high precision, low cost, and has excellent responsiveness, and the overall system It has various excellent effects such as improving the driving efficiency of the motor.

[Brief explanation of the drawing]

Fig. 1 is a schematic configuration diagram of the entire power steering device showing one embodiment of the hydraulic reaction device according to the present invention, and Fig. 2 is an enlarged sectional view of an on/off type rotary valve that characterizes the present invention. , FIGS. 3(a) and 3(b) are sectional views taken along the line ■-■ to explain its operation, FIG. 4 is a sectional view taken along the same <IV-■ line, and FIG. 5 explains the operation of the return mechanism. A schematic diagram, FIG. 6, and a hydraulic circuit diagram thereof, FIG. 7(a). (b) and (c) are characteristic diagrams showing the control current to the on/off type rotary valve that characterizes the present invention and the amount of oil pressure supplied by the on/off drive, and Figs. 8 and 9 are A characteristic diagram for explaining the hydraulic reaction force control state, FIG. 10 is a block diagram for explaining the control circuit in the controller, and FIGS. 11 to 16 are hydraulic circuits showing other embodiments of the present invention. It is a diagram. DESCRIPTION OF SYMBOLS 1... Power steering main body part, 2... Main body, 3... Rotary flow path switching valve, 5... Oil pump, 6... Power cylinder, 7... ... Oil tank, 8 ... Steering handle, 20 ... Hydraulic reaction force device, 25 ... Hydraulic reaction force chamber, 30 ... On/off type turn for hydraulic reaction force control. Dynamic valve (rotary valve), 31...Reaction hydraulic pressure supply passage (hydraulic passage), 3
2...Controller, 33...Vehicle speed sensor, 3
4... Steering sensor, 36... Sleeve, 36b
... Passage hole, 37... Rotor, 37a...
Passage groove, 38... Pump port, 40... Reaction force chamber boat, 48... Reaction hydraulic pressure return passage (hydraulic passage)
.

Claims (3)

[Claims] (1) Equipped with an on/off type rotary valve installed in the hydraulic passage to control the reaction oil pressure supplied to the hydraulic reaction chamber, and this rotary valve can be adjusted according to vehicle speed and steering angle. A hydraulic reaction force device for a power steering device, characterized in that the hydraulic passage is driven to open and close by an output pulse signal with a duty ratio sent from a controller according to the magnitude. (2) The hydraulic reaction force device for a power steering device according to claim 1, wherein the rotary valve is constituted by a rotary valve rotatably driven by a rotary drive source. (3) A hydraulic reaction force device for a power steering device according to claim 1, wherein the rotary valve is constituted by a swinging valve driven to swing by a swinging drive source.