JPH0631001B2 - Steering force control device for power steering device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to a steering force of a power steering apparatus that includes a reaction force mechanism that supplies hydraulic pressure according to vehicle speed and changes steering wheel torque according to vehicle speed. The present invention relates to a control device.

<Prior Art> A device that controls the steering force of the power steering device according to the vehicle speed by introducing an oil pressure proportional to the vehicle speed into the reaction force mechanism, especially the oil pressure introduced into the reaction force mechanism. It is publicly known that control is performed by using pressure oil in a high-pressure line that connects the intake device and the supply pump.

Generally, in this type of control device, it is necessary to lower the oil pressure applied to the reaction force mechanism during low speed traveling that requires steering pressure, and conversely to increase the steering pressure during high speed where almost no steering pressure is required.

Conventionally, as shown in FIG. 11, the hydraulic pressure applied to the reaction mechanism 100 is controlled by a flow control valve 130 that divides the fluid, which is supplied from the pump 110 and whose flow rate is controlled, into the power steering device 120 and the reaction mechanism 100. An electromagnetic control valve 140 is provided for controlling the discharge amount of this branched fluid to the oil tank side by a signal such as a vehicle speed. Further, in order to increase the change in steering force during high-speed traveling, a steering pressure response variable throttle 150 is provided in the diversion passage 160 in order to increase the diversion ratio to the reaction force mechanism side as the steering pressure increases.

<Problems to be Solved by the Invention> Since steering pressure is introduced at one end of the variable throttle valve 150 and reaches the relief set pressure at maximum load, the spring constant of the spring 151 incorporated therein is high. It is set. Along with this, the valve operating range x also varies and the variable throttle area change of the diversion control valve 130 also increases as shown in FIG. Therefore, the operating range x needs to be adjusted, and not only an adjusting mechanism is required, but also the assembling adjustment is troublesome and the cost is increased.

<Means for Solving the Problems> The present invention is intended to reduce the variation in the flow control characteristics of the shunt control valve due to the variation in the operating range x of the variable throttle valve. A fixed throttle is provided in series with the variable throttle. It is a thing.

<Operation> Since the fixed throttle is inserted in series with the variable throttle in the present invention, even if there is a variation in the throttle opening with respect to the steering pressure, the degree of change as the combined throttle resistance in the shunt flow path is reduced.
As shown in FIG. 0, the amount of change in Δq is small, the variation in the flow control characteristics of the diversion control valve is very small, and no special adjusting means for determining the operating range of the variable throttle valve is required. Therefore, there is no need for adjustment after assembly.

<Examples> Examples of the present invention will be described below with reference to the drawings. In FIG. 1, 11 is a housing main body which is the main body of the power steering apparatus, and 12 is a valve housing fixed to the housing main body 11. A pinion shaft (output shaft) 21 is rotatably supported in the housing body 11 and the valve housing 12 via a pair of bearings 13 and 14, and the pinion shaft 21 slides in a direction intersecting with the pinion shaft 21. The rack teeth 22a of the possible rack shaft 22 mesh with each other. The rack shaft 22 is connected to a piston of a power cylinder 90 (see FIG. 3), and both ends of the rack shaft 22 are connected to steering wheels via a required steering link mechanism.

A servo valve 30 is housed in the valve hole of the valve housing 12. The servo valve 30 has an input shaft 23 as a steering shaft.
A rotary valve member 31 integrally formed with the rotary valve member 31 and a sleeve valve member 32 concentrically and relatively rotatably fitted to the outer periphery of the rotary valve member 31 are main components. The rotary valve member 31 is flexibly connected to the pinion shaft 21 via a torsion bar 24, one end of which is connected to an input shaft 23 that is integral with the rotary valve member 31.

Further, although not shown on the outer circumference of the rotary valve member 31,
A plurality of lands extending in the axial direction and the groove are formed at equal intervals, and a communication passage 37 is formed so as to communicate from the groove bottom to the inner peripheral portion. A passage 39 that connects the input shaft 23 with the inner peripheral portion and the low-pressure chamber 38 in the valve housing 12.
Is provided. On the other hand, on the inner circumference of the sleeve valve member 32, a plurality of lands extending in the axial direction and grooves are formed at equal intervals, and distribution holes 40, 41 opening from the respective grooves to the outer circumference of the sleeve valve member 32 are provided. There is. When the servo valve is in the neutral state, the pressure fluid supplied from the supply port 35 flows evenly in the groove portions on both sides of the land portion, and then flows out from the low pressure chamber 38 to the discharge port 36 via the communication passage 37 and the passage 39. In this case, the power cylinder 90 is not operated because both distribution ports 33 and 34 have low pressure and equal pressure. When the servo valve 30 is deviated from the neutral state, pressure oil is supplied to the one distribution hole 40 or 41 from the supply port 35, and the power cylinder 90 is supplied to the other distribution hole 41 or 40.
The fluid discharged from the inlet flows into the communication passage 37, the passage 39,
It is designed to be discharged to the discharge port 36 via the low pressure chamber 38.

The reaction force mechanism is as follows. As shown in FIG. 2, the rotary valve member 31 is provided at its end portion on the pinion shaft 21 side with protrusions 50 protruding in both radial directions, and the pinion shaft 21 corresponding to the protrusion 50 has a protrusion. A fitting groove 51 is formed in which the portion 50 is loosely fitted around the axis of the input shaft 23 so as to be pivotable by a small angle.

Insertion holes 53 are formed on both sides of the pinion shaft 21 so as to sandwich the projection 50, and plungers 54 are slidably inserted into the insertion holes 53, respectively. The plunger 54 is projected forward by the hydraulic pressure introduced into the reaction force chamber 55 formed in the rear of the plunger 54, and holds the protrusion 50 from both sides thereof, and the forward end of the plunger 54 has the forward end.
It is regulated by the large-diameter portion 54a formed in No. 4.
Reference numeral 57 is a port for introducing hydraulic pressure according to the vehicle speed, 58 is a passage, and 59 is an annular groove that connects the passage 58 and the reaction chamber 55.

The reaction force mechanism having the above-described structure applies hydraulic pressure in the direction in which the protrusions 50 are rotated by the plungers 54 provided on both sides of the protrusion 50. It may be a thrust type one that is pressed by or in the axial direction.

In Figure 3, 64 is a flow control valve for controlling the flow rate Q _O the discharge pressure oil from the supply pump 60 which is driven by the vehicle engine at a constant flow rate Q _C. This flow control valve 6
Reference numeral 1 denotes a metering orifice 62 and a bypass valve 64 which is operated according to the front-rear pressure of the metering orifice 62, and which controls the opening of a bypass passage 63 communicating with the low pressure side so as to keep the front-rear pressure constant. It is configured. If the supply pump 60 discharges a constant flow rate of a constant speed motor drive type, the flow rate control valve 6
1 is unnecessary.

Reference numeral 65 denotes the high pressure side of the flow control valve 61 and the first supply passage 66.
It is a diversion control valve (flow divider) connected via. The diverter valve 65, the flow rate Q of the flow rate _{Q G} of the second supply passage 45 of the servo valve 30 side by the flow rate _{Q C} of the control spool 67, into the second branch passage 46 of the reaction chamber 55 side
Divide into _R and.

Reference numeral 80 is a variable throttle valve. This throttle valve 80 has a passage 91
Gear generation pressure P _G introduced via the spring and the spring 82
It has a sliding spool 83 that slides on the basis of the pressure balance with the repulsive force, and forms a diversion throttle 84 between the sliding spool 83 and the valve hole. The diversion restrictor 84 functions as a fixed restrictor in the initial state, and thereafter functions as a variable restrictor whose restrictor opening area changes with the displacement of the sliding spool 83 due to the gear-generated pressure P _G. A fixed throttle 85 is provided in series with the diversion throttle 84, and the first branch passage 9
The flow rate of the pressure oil flowing through No. 3 is controlled. One end of the branch passage 93 communicates with the front chamber 96 of the diversion control valve 65 via the supply passage 66 and a small hole 95 formed in the control spool 67, and the other end thereof communicates with the control spool 67. The holes 97 and 98 communicate with the rear chamber 99 of the diversion control valve 65. Therefore, the pressure balance between the front and rear chambers 95 and 99 of the diversion control valve 65 changes due to the change of the throttle opening area of the diversion throttle 84 of the throttle valve 80, and the opening degree between the first supply passage 66 and the second supply passage 45 and By adjusting the opening between the first branch passage 93 and the second branch passage 46, the second valve on the servo valve 30 side can be adjusted.
And the flow rate Q _G of the supply passage 45, so as to change the shunt ratio between the flow rate Q _R of the second branch passage 46 of the reaction force chamber 56 side. In addition, 69 is a balance spring.

An electromagnetic control valve 70 controlled according to the vehicle speed or the like is inserted in the passage 46 on the reaction force chamber 55 side. As shown in FIG. 4, the electromagnetic control valve 70 includes a valve body 71 and a spool 7 slidably fitted in an inner hole of the valve body 71.
2 and a solenoid 73 to which a current I corresponding to a vehicle speed signal V is supplied from a solenoid control circuit (not shown) controlled by a computer or the like. The spool 72 is normally held at the lower end by a spring 74, and the small hole 7 is formed between the flow control valve 65 and the passages 76 and 77 leading to the tank.
It communicates only with 8. Then, when the solenoid 73 is energized, the spool 72 is displaced against the spring 74 in accordance with the current value I and the passages 76 and 77 are opened through the small holes 78.
In addition, the slit 79 is used for communication.

In FIG. 3, 90 is a power cylinder, and 94 is a safety relief valve that releases the pressure when the pressure in the passage 46 exceeds a predetermined pressure.

Next, the operation of the above configuration will be described. Supply pump 60
Controlled to a constant flow rate Q _C and the flow rate Q _O more discharged pressure oil in the flow control valve 61. Each flow rate Q _G to this constant flow rate Q pressure oil is controlled to _C is servo valve with a shunt characteristic shown in FIG. 5 by the flow dividing control valve 65 30 side and the reaction force chamber 56 _side, is diverted to the Q _R It In the low speed state, a large current I is supplied to the solenoid 73 as shown in FIG.
As a result, the spool 72 of the electromagnetic control valve 70 is largely displaced, and the slit 79 is fully opened. Therefore passage 46
Pressure oil is diverted to the side is drained into the tank, reaction-force oil pressure P _R is hardly generated. Therefore, when the input shaft 23 is rotated by the handle operation, the plunger 54 is easily pushed back, whereby the sleeve valve member 32 and the rotary valve member 31 are relatively rotated, and the gear generation pressure P _{G with} respect to the manual torque T _M is changed. The change has the characteristics shown by the curve of low speed and stationary rotation in FIG. 9, and a light steering wheel operation can be performed.

After that, when the vehicle speed increases, the solenoid 73 of the electromagnetic control valve 70 follows the increase of the vehicle speed signal V as shown in FIG.
The control current value I supplied to is reduced. As a result, the spool 72 is displaced and the opening of the slit 79 is reduced,
As a result, the flow rate of the hydraulic pressure returned to the tank is limited and the reaction force hydraulic pressure P _R is increased. With increasing pressure hydraulic P _R, the pressing force of the plunger 54 is increased relative to the protrusion 50, it is correspondingly handle becomes heavy.

On the other hand, when the handle is operated, the gear generation pressure P _G is generated in the passage 45 communicating with the servo valve 30 side. This gear generation pressure P _G causes the throttle opening area S of the diversion throttle 84 of the throttle valve 80 to gradually increase as shown in FIG.
When 3 reaches the stroke end, it becomes constant. As a result, the fluid flows into the diversion control valve 65 via the diversion throttle 84 of the throttle valve 80 and the fixed throttle 85. This shunt restrictor 8
5 and the fixed throttle 85 are provided in series, the rate of change of the combined flow resistance becomes smaller than the rate of change of the shunt throttle 84 alone. As a result, the front and rear chambers 9 of the diversion control valve 65
The change in the pressure balance of Nos. 6 and 99 is also small, and the change in the flow rate characteristic of the flow dividing valve is small. The shunt characteristics becomes possible to increase the shunt flow rate Q _R of the counter force chamber side with reducing the shunt system quantity Q _G with increasing gears developed pressure as shown in FIG. 5, the increase of the shunt flow rate Q _R The reaction force hydraulic pressure P _R increases according to the gear generation pressure P _G. The reaction-force oil pressure P _R is slow as is evident from FIG. 8, the degree of increase is low in the据切state, whereas tends to rapidly increase with increasing speed, the gear occurs for manual torque T _M pressure P _G
The change characteristic of is as shown in FIG. In particular, since in the configuration in which a variable throttle in series with the fixed throttle, the influence of the variable throttle actuation thereof variation even if there are variations in the range is absorbed by the fixed throttle, manual torque T _M is at low speed
Since the gear generation pressure P _G is low, the steering wheel becomes heavier as the steering wheel is cut in at high speeds, and a steering feeling with a feeling of crunch can be obtained.

<Effects of the Invention> As described in detail above, the device of the present invention is provided in the middle of the supply passage that connects the supply pump and the servo valve and the branch passage that branches from the supply passage and connects to the reaction chamber. According to the pressure difference in the branch passage, the flow control valve that adjusts the opening of the supply passage and the branch passage to change the flow rate supplied to the servo valve and the reaction chamber, and the branch passage upstream of the flow control valve A variable throttle provided on the way to change the pressure difference between the supply passage on the upstream side of the diversion control valve and the branch passage by increasing the opening of the branch passage according to the increase in the gear generated pressure due to the steering of the servo valve. Since it is provided in series with the throttle and has a fixed throttle that generates a pressure difference between the supply passage on the upstream side of the diversion control valve and the branch passage, there is variation in the operating range due to the high spring constant of the variable throttle. Even if there is a change in shunt characteristics As a result, this can be greatly reduced. As a result, no special adjustment means for the operating range is required, so that the mechanism can be simplified and the assembly can be facilitated. Furthermore, in high-speed driving conditions, the gradient of the characteristic of the pressure generated by the gear against the manual torque can be reduced to reduce the power assist, which makes it possible to obtain a steering feeling with a feeling of touch as the steering wheel is cut during high-speed driving. Have the effect of being

[Brief description of drawings]

The drawings show an embodiment of the present invention. FIG. 1 is a sectional view of a power steering apparatus, FIG. 2 is a sectional view taken along the line II-II of FIG.
FIG. 3 is a hydraulic system diagram of the present invention, FIG. 4 is a cross-sectional view of an electromagnetic control valve, FIG. 5 is a diagram showing a diversion characteristic of a diversion control valve, and FIG. 6 is a diagram showing a control characteristic of an electromagnetic control valve. FIG. 7 is a diagram showing the control characteristic of the throttle valve, FIG. 8 is a diagram showing the change characteristic of reaction force hydraulic pressure, FIG. 9 is a diagram showing the change characteristic of gear generation pressure, and FIG.
The figure shows the flow rate control characteristics when a fixed throttle is placed in the branch channel, and FIGS. 11 and 12 show the conventional device.
FIG. 11 is a hydraulic system diagram, and FIG. 12 is a diagram showing changes in variable throttle area of the flow dividing control valve due to variations in the valve body operating range x. 21 ... Pinion shaft, 23 ... Input shaft, 30 ... Servo valve, 45 ... Second supply passage, 46 ... Second branch passage, 5
0 ... Projection, 54 ... Plunger, 55 ... Reaction chamber,
65 ... Flow control valve, 66 ... First supply passage, 70 ...
Electromagnetic control valve, 80 ... Variable throttle valve, 84 ... Shunt throttle,
85: fixed throttle, 93: first branch passage.

Claims (1)

[Claims] 1. A servo valve which is operated based on relative rotation between an input shaft and an output shaft to control supply and discharge of pressure oil to and from a power cylinder, and a reaction force mechanism which changes a steering wheel torque according to a vehicle speed. In a steering force control device of a power steering device, which is provided on a passage communicating with a reaction force chamber of a reaction force mechanism and includes an electromagnetic control valve for controlling pressure oil generated in the reaction force chamber according to a vehicle speed, a supply pump Is provided in the middle of a supply passage connecting the servo valve and the supply passage and a branch passage branched from the supply passage and connected to the reaction chamber, and the opening degrees of the supply passage and the branch passage are adjusted according to the pressure difference between the supply passage and the branch passage. Depending on the increase in the pressure generated by the gear, which is provided in the middle of the branch passage upstream of the diversion control valve and the diversion control valve that adjusts to change the flow rate supplied to the servo valve and the reaction chamber. Divergence control by increasing the opening of the branch passage A variable throttle that changes the pressure difference between the upstream supply passage and the branch passage, and a fixed throttle that is provided in series with the variable throttle and that generates a pressure difference between the upstream supply passage and the branch passage of the diversion control valve. Steering force control device for power steering system.