JPH0214536Y2 - - Google Patents

Description

[Detailed description of the invention] This invention transmits the movement of the handle to the oil passage switching valve via a torsion bar, and a high-pressure oil passage extends from the oil pump to the oil passage switching valve, and from the oil passage switching valve to the oil tank. This invention relates to an improvement in a power steering device that operates a power cylinder in a predetermined steering direction by switching between a low-pressure oil passage and a high-pressure oil passage, and also guides a portion of the hydraulic oil flowing through the same high-pressure oil passage to a reaction piston to regulate torsion bar torsion. A parallel oil passage branched from the middle of the oil passage extending from the high pressure oil passage to the pressure piston, an orifice provided on one side of the parallel oil passage, and hydraulic oil from the parallel oil passage proportional to the vehicle speed. a flow rate control valve that discharges the piston, an orifice that generates a pilot pressure according to the flow rate on the downstream side of the flow control valve, and an orifice that is actuated by the pilot pressure to maintain a constant hydraulic pressure in the oil passage to the reaction piston. It is equipped with a pressure control valve that controls the pressure so that it increases as the speed increases,
The flow control valve is loosely fitted around a plunger, a spring that biases the plunger toward a high speed position, and an electromagnetic coil that operates the plunger toward a low speed position against the biasing force of the spring. It is characterized by comprising a spool, a tightening fixing member for tightening and fixing the spool to the plunger, and a sleeve disposed around the spool in a fluid-tight manner. It can be steered easily and provides a moderate response (feeling of reaction force) at high speeds. Another object of the present invention is to provide an improved power steering device that can smoothly operate a flow control valve.

Next, the power steering device of the present invention will be explained with reference to an embodiment shown in FIGS. 1 to 25. First, to explain the outline with reference to FIG. 1, 1 is an oil pump driven by an engine (not shown), and the oil pump 1 has a constant flow rate (7/
min), the discharge pressure is variable (5Kg/cm ² ~70Kg/
cm ² ) oil pump. Further, 2 is a four-way oil passage switching valve (rotary valve), 3 is a steering power cylinder, 4 is an oil tank, 5 is a plurality of reaction force pistons, 6 is a chamber formed behind each pressure piston 5, and 7a is a high-pressure oil passage extending from the oil pump 1 to the oil passage switching valve 2, 8a is a low-pressure oil passage extending from the oil passage switching valve 2 to the oil tank 4, and 9a and 10a are from the oil passage switching valve 2. An oil passage extending to the power cylinder 3, 7b is an orifice provided in the middle of the high-pressure oil passage 7a, 7b is a bypass oil passage connected to the high-pressure oil passage 7a on the upstream and downstream sides of the orifice a, and 11 is the same. Change over valve interposed in the middle of bypass oil passage 7b, 12
is a pressure control valve (hereinafter referred to as a pressure control valve) connected to the oil passage 7b on the upstream side of the change-over valve 11 via an oil passage 7c; 13 is a flow control valve (hereinafter referred to as a solenoid valve); 7d; is an oil passage extending from the pressure control valve 12, and parallel oil passages 7e and 7e' branched from the oil passage 7d extend to the solenoid valve 13. Further, 7d ₁ is a pilot oil passage extending from the middle of the oil passage 7d to the pressure control valve 12, 7d ₂ is an oil passage extending from the middle of the oil passage 7d to the chamber 6 behind the reaction piston 5, and 7d. ₃ is an oil passage extending from the middle of the oil passage 7d to the low pressure oil passage 8b, b and c are orifices provided in the middle of the oil passages b and c, and 7e ₁ is an oil passage 7e between the orifices b and c. 7f is an oil passage extending from the solenoid valve 13 to the low pressure oil passage 8b, and d is an orifice provided in the middle of the oil passage _7d3 . The orifice 7f 1 is installed in the middle of the oil passage 7f, and the oil passage ₇ is located upstream of the orifice d.
a main pilot oil passage extending from f to the pressure control valve 12; 14 a vehicle speed sensor; 15 a control device; 16 an ignition switch; 17 an ignition coil; With the wiring, the vehicle speed sensor 14 detects the vehicle speed and sends the resulting pulse signal (pulse signal according to the vehicle speed) to the control device 15. A current corresponding to the vehicle speed (from a predetermined zero current at high speed (i = 0) to maximum current (i = 1) when stopped) is sent to the electromagnetic coil 57 of the solenoid valve 13, and the solenoid The plunger 52 and spool 51 of the valve 13 are held at predetermined positions according to the above-mentioned current value. Next, the oil passage switching valve 2, change over valve 11, pressure control valve 12, and solenoid valve 13 will be explained in detail with reference to FIGS. 2 to 21. 20 in FIGS. 2 to 7 is a valve housing, and each of the above-mentioned valves 2, 11, 12,
13 is incorporated into the same valve housing 20. First, to explain the oil passage switching valve 2 in detail with reference to Fig. 2, 21 is an input shaft operated by a handle (not shown), and 23 in Figs. 2 and 3 is rotated within the valve housing 20 by upper and lower bearings. A cylinder block 22 is supported on the input shaft 21.
The upper part of the torsion bar 22 is fixed to the upper part of the input shaft 21, and the lower part of the torsion bar 22 is fixed to the cylinder block 23. Reference numeral 21a denotes a plurality of vertical grooves provided on the outer circumference of the lower part of the input shaft 21, and the cylinder block 23 is provided with a cylinder facing each of the vertical grooves 21a, and each cylinder is provided with the reaction piston. 5 is fitted and inserted, and the protrusions provided at the tips of the reaction pistons 5 are engaged with the longitudinal grooves 21a. The chamber 6 behind each pressure piston 5 is formed between the cylinder block 23 and the valve housing 20 and is an annular groove. Further, 23a is a pinion integrated with the cylinder block 23, and 24
a is a rack engaged with the pinion 23a, 24 is a rack support, 26 is a cap, 25 is a spring interposed between the cap 26 and the rack support 24, and 28 is the valve housing 20 directly above the cylinder block 23. a sleeve of the oil passage switching valve 2 fixed therein; oil passages 28a, 28b, and 28c provided on the outer peripheral surface of the sleeve 28; a valve body in which 27 is fitted between the sleeve 28 and the input shaft 21; 23b is a pin connecting the lower end of the valve body 27 and the upper end of the cylinder block 23, and 27a, 27b, and 27c are oil passages provided on the outer peripheral surface of the valve body 27. When the handle is in the neutral position, high pressure The oil passage 7a is the oil passage 27a of the valve body 27 and the oil passage 2 of the sleeve 28.
8a, the input shaft 21 and the torsion bar 22
The hydraulic oil from the oil pump 1 is connected to the chamber 29 between the high pressure oil passage 7a → oil passage 28a →
Turn the handle to the right so that the oil circulates from oil passage 27a to chamber 29 (the oil passage between oil passage 27a and chamber 29 is not shown) → low pressure oil passage 8a → oil tank 4 → oil pump 1. Then, when the input shaft 21 is rotated to the right relative to the valve body 27, the high pressure oil passage 7a is connected to the oil passages 27a, 27b of the valve body 27 and the oil passage 27 of the sleeve 28.
b to the oil passage 9a of the power cylinder 3, and the low pressure oil passage 8a communicates with the oil passage 10a of the power cylinder 3 via the chamber 29, the oil passage 27c of the valve body 27, and the oil passage 28c of the sleeve 28, respectively. The hydraulic oil from the oil pump 1 is sent to the high pressure oil passage 7a → oil passage 27a → oil passage 28b → oil passage 9a → the left chamber of the power cylinder 3, while the oil in the right chamber of the power cylinder 3 is sent to the oil passage 10a. → Oil passage 28c → Oil passage 27c → Chamber 29 → Low pressure oil passage 8a → Returned to tank 4, the piston rod of power cylinder 3 moves to the right, and the steering wheel is turned to the left so that steering to the right is performed. Input shaft 21
When rotated to the left relative to the valve body 27, the high pressure oil passage 7a connects to the oil passage 2 of the valve body 27.
7a and the oil passage 28c of the sleeve 28 to the oil passage 10a of the power cylinder 3; The hydraulic oil from the oil pump 1 is communicated with the oil passages 9a through the high-pressure oil passage 7a → the oil passage 27.
a → Oil passage 28c → Oil passage 10a → Power cylinder 3
On the other hand, the oil in the left chamber of the power cylinder 3 is returned to the oil passage 9a → oil passage 28b → oil passage 27b → chamber 29 → low pressure oil passage 8a → tank 4,
The piston rod of the power cylinder 3 has moved to the left, so that steering to the left is performed. Next, the change-over valve 11 will be explained in detail.As is clear from FIGS. 4 and 7, the change-over valve 11 is interposed in the middle of the bypass oil passage 7b of the orifice a. . The change over valve 11 has an annular groove 30a (this annular groove 30a is a part of the oil passage 7b).
A spool 30 (the spool 30 is shown in a high-speed position) and a cap 31 with a spring 3 interposed between the spool 30 and the cap 31
3 and an O-ring 34, the pilot oil passage 7e ₁
(See Figure 1) When the oil pressure increases, the spool 30
moves forward against the spring 33 to open the bypass oil passage 7b, and when the oil pressure in the pilot oil passage _7e1 decreases, the spool 30 moves backward by the spring 33 to close the bypass oil passage 7b. ing. Next, to explain the pressure control valve 12 in detail, the pressure control valve 12 has a spool 40 and a spool 4, as is clear from FIGS.
1, the cap 42, the stopper 43, and the spring 4 interposed between the spool 41 and the stopper 43.
4 and a member 45 having an orifice d fixed within the spool 41. Further, the spool 41 is provided with three annular grooves 41a, 41b, and 41c as shown in FIGS.
Oil passage 7c branched from the upstream side of over valve 11
is facing. Also, 41d is the orifice d
A chamber 41e extends upward within the spool 41 from the chamber 41d and the annular groove 4.
1c (note that these 41d, 41
e, 41c is a part of the low pressure oil passage 8b), and the annular groove 41c is a part of the low pressure oil passage 8b formed directly above the valve body 27 of the oil passage switching valve 2 shown in FIG. It faces the pressure transmission oil passage 8b on the valve housing 20 side that extends diagonally downward. Further, the annular groove 41a communicates with the chamber 41d via an orifice e. Also, the sleeve 4
0, as shown in FIGS. 11 to 17, from the top to the bottom with different phases in the circumferential direction of the outer peripheral surface,
A notch 40a having a through hole 40a' and a through hole 40
Notch 40b with b', notch 40c with through holes 40c' and 40c'', and notch 4 with orifice b
A notch 40e having a through hole 40e' is provided, and a hole 40a' having a through hole 40a' is provided with a spool 41
The annular groove 41c of the spool 41 and the low pressure oil passage 8b on the valve housing 20 side are connected, and the notch 40b having the through hole 40b' connects the annular groove 41a of the spool 41 and the oil passage 7c on the valve housing 20 side.
The notch 40c with 0c′, 40c″ is the spool 41
Connect the annular grooves 41a and 41b of the orifice b
The notch 40d has an annular groove 41 of the spool 41.
b and the oil passage 7e on the valve housing 20 side, and the notch 40e having the through hole 40e' connects the annular groove 41b of the spool 41 and the oil passage 7d on the valve housing 20 side shown in FIGS. , the oil coming out from the orifice d to the chamber 41d of the spool 41 flows through the oil passage 41e → the annular groove 41c → the through hole 40.
a′ → notch 40a → return to the oil tank 4 via the low pressure oil passage 8b on the valve housing 20 side.
The notch 40 passes from the bypass oil passage 7b to the oil passage 7c.
The hydraulic oil that has entered b flows through the through hole 40b' → annular groove 41a.
→Notch 40c→Through hole 40c″→Annular groove 41b→
A portion of the hydraulic oil flowing in the annular groove 41b passes through the through hole 40e'→notch 40e→oil passage 7d of the valve housing 20 toward the solenoid valve 13 and reaction piston 5, and flows through the orifice b→ Notch 40d→change over valve 11 via oil passage 7e on valve housing 20 side
Acts as a pilot pressure behind the spool 30 (see 7e ₁ in Fig. 5), and further
The oil passage 30b provided at the rear end (see FIG. 7) is directed toward the solenoid valve 13 via an oil passage 7e on the valve housing 20 side. Next, to specifically explain the solenoid valve 13, the solenoid valve 13 has the fifth, eighth, and 21st
As is clear from the figure, the pressure control valve 12
They are arranged directly below the , so that their axes coincide with each other. The solenoid valve 13 has a sleeve 50
a spool 51, a plunger 52 made of a non-magnetic material, a member 53 made of a magnetic material integrated with the plunger 52, a lock nut 54 for tightening and fixing the spool 51 to the plunger 52, and the pressure control valve 1.
The seat plate 55 that comes into contact with the sleeve 40 of No. 2 and the seat plate 5
5 and the back-up spring 56 and electromagnetic coil 57 interposed between the sleeve 50, a nut 58 fixed to the casing on the side of the electromagnetic coil 57, a plunger pressing force adjustment bolt 59 screwed into the nut 58, and the bolt 59. and the plunger 52
Spring 60 and solenoid valve 13 interposed between
and a lock nut 61 for tightening and fixing the assembly to the valve housing 20, and the sleeve 50
As shown in FIG. 21, the valve housing 2
Oil passage 5 communicating with oil passage 7d on the 0 side (see Figure 5)
0a and an oil passage 50b communicating with an oil passage 7e on the valve housing 20 side, and an orifice c is provided in the oil passage 50b. In addition, the spool 51
The plunger 52 has an oil passage 51a having an oblique groove 51a' and a through hole 51b, and an oil passage 52a, a through hole 52b, and an axial oil passage 52c communicating with the through hole 51b. Each is provided. As already mentioned, the oil passage 7d on the valve housing 20 side shown in FIG.
Hydraulic oil heading towards the solenoid valve 13 enters the oil passage 50a in FIG. 21, and hydraulic oil flowing towards the solenoid valve 13 through the oil passage 7e on the valve housing 20 side shown in FIG. FIG. 21 shows the state at high speed, and in this state, only the hydraulic oil that has entered the oil passage 50b flows from the orifice C → oil passage 51a → through hole 51b → oil passage 52a → through hole 52b → oil passage 52c.
It then goes to the member 45 on the orifice d side. Also, when the speed is high → low, the spool 51 descends and reduces the opening amount of the orifice c.
By increasing the opening amount of the oil passage 50a, when the vehicle is stopped,
Only the oil passage 50a is opened. In Figure 1, Q ₀ is the flow rate on the discharge side of the oil pump 1, and Q ₁ is the high pressure oil line 7.
The amount of oil in a, Q ₂ is the flow rate in oil passage 7c, and Q ₃ is the flow rate in oil passage 7d.
(The flow rate of oil passage 50a, Q ₄ is the flow rate downstream of orifice c, and Q ₅ is the flow rate downstream of orifice e, and Q ₁ :Q ₂ is approximately 6:1. Also, oil passage 7
The flow rate Q ₂ of c is Q ₂ = Q ₃ + Q ₄ + Q ₅ (30th
(see figure). The diameter of the sleeve 50 of the solenoid valve 13 is different at the top, middle, and bottom as shown in _FIG .
D There is a difference of ₂ . On the other hand, the sleeve fitting hole on the valve housing 20 side is also opened to match the sleeve fitting hole. This is done in order to reduce frictional resistance when inserting the sleeve 50 into the sleeve insertion hole of the valve housing 20 together with the O-ring 62, making it easier to insert the sleeve 50 into the sleeve insertion hole. . Further, the filter 70 is shown in FIGS. 22, 23, and 24. This filter 70 is
Composed of a frame 71 and a wire mesh 72, the pressure control valve 12
Notch 40b (9th, 1st) provided in the sleeve 40 of
(see Figure 3), that is, it is fitted at the entrance of the control system oil passage to prevent foreign matter such as dust from entering the control system oil passage. To prevent foreign matter such as dust from entering the control system oil path, use this type of filter in the valve casing 20.
It may be provided at the inlet of the high pressure oil passage 7a (see the arrow in Figure 4) provided in It is difficult to store this filter due to the space available. The entrance of the high-pressure oil passage 7a is made large in diameter by inserting a drill into the orifice a and the oil passage 7, which are branched into two directions.
(b) and piping (not shown)
This is to facilitate the connection work. In addition, other oil passages 7b (oil passages 7b, 7c, 7d on the downstream side of the change over valve 11,
As can be seen from FIGS. 3, 4, and 5, holes 7e, etc. are also formed by drilling holes in the vertical and horizontal directions in the valve housing 20 and plugging them, which also facilitates the machining of the oil passages. In addition, 2nd, 3rd, 4th,
Z in Figures 6 and 7 is the central axis of the oil passage switching valve 2,
_Z1 in FIG. 5 is the center of the pinion 23a. Further, an example of the control device 15 is shown in FIG. 25. 80
81 is a constant voltage power supply circuit, 81 is a pulse/voltage conversion circuit that sends out a voltage proportional to the vehicle speed, 82 is an error amplifier circuit, 83 is a transistor, 84 is a timer circuit 87 that resets the timer circuit 87 when the vehicle speed is other than zero, and when the vehicle speed is zero, the timer circuit 87 85 is a pulse/voltage conversion circuit that sends out a voltage proportional to the engine speed, 86 is an engine speed setting circuit, and 88 is a timer circuit when the engine speed is 2000 rpm or more.
7 is the engine speed setting circuit that puts it in the starting state and turns it off when the speed is below 2000 rpm, 88 is the vehicle speed input disconnection detection circuit that is in the ON state without a vehicle speed pulse, 89 is the transistor, 90 is the relay, and 91 is the electromagnetic coil of the solenoid valve 13. With the negative feedback circuit that stabilizes the current flowing through the control device 57, the following effects can be obtained according to the present control device 15. In other words, it is normally impossible for the engine speed to exceed 2000 rpm when the vehicle speed is zero. Therefore, if this condition continues for 5 to 10 seconds or more, it is determined that some kind of failure has occurred (for example, a failure in the vehicle speed pulse system or a failure in the solenoid valve system), and the relay 90 is turned on and the solenoid valve 13 (electromagnetic valve 13) is turned on. The power supply to the coil 57 is stopped.Therefore, the steering wheel becomes difficult to operate at high speeds (having a fail-safe function) and is safe.

Next, the operation of the power steering device will be explained. Output oil pressure of oil passage switching valve 2 (oil pump 1
The discharge pressure (Pp) of the valve body 27 of the input shaft 21 is determined by turning the handle to the right or left from the neutral position.
As the relative angle to the curve increases, the curve rises as shown in FIG. 26, drawing a quadratic curve. The influence of the discharge pressure Pp of the oil pump 1 is the oil passages 7a, 7b, 7
For the orifices b and e solenoid valves 13 and the reaction piston side chamber 6 on the downstream side via the c pressure control valve 12, there is an oil passage 7d on the upstream side.
This appears as it is, and the oil pressure Pc of the same oil passage 7d rises in the same way. At this time, if the vehicle is stopped, the control device 15 receives a pulse signal from the vehicle speed sensor 14, sends a current of i=1A (see FIG. 29) to the solenoid valve 13, and
2 and the spool 51 to the lower limit position (moved to the L position in FIG. 1), and the oil passage 5 in FIG.
Only 0a is the oil passage 51a, 51 on the spool 51 side.
b, 52b to communicate with the oil passage 7f on the upstream side of the orifice d, so that the oil pressure in the oil passage 7f is transferred to the oil passage 7d.
Set it to the same value as the hydraulic pressure Pc. If you start turning the steering wheel to the right (or left) when stopped above, oil path 7d
The hydraulic pressure PC starts to rise. Then, oil path 7
The oil pressure of f also increases by the same value. This oil pressure is directly transmitted to the spool 41 (the small diameter end of the spool 41) of the pressure control valve 12 via the main pilot oil passage _7f1 , and the spool 41 is pushed in the direction of the arrow in FIG. At the same time, the annular groove 41b of the spool 41
The hydraulic oil passing through pushes the spool 41 in the direction of the arrow in FIG. 10 due to the difference in pressure receiving area. On the other hand, the spring 44 side is connected to the low pressure oil passage 8b, and the spool 41 gradually rises against the spring 44 (moves in the L direction in FIG. 1), and the opening degree of the through hole 40b' gradually becomes smaller. When the hydraulic pressure pushing in the direction of the arrow and the spring force are balanced, the spool 41 stops. In this state, the opening degree of the through hole 40b' is the smallest, and the oil passage 7
The oil pressure Pc of d (reaction piston side chamber 6) is the lowest. This condition remains the same from then on, and by turning the steering wheel further to the right (or left),
Even if the oil pressure Pp of a, 7b, 7c increases further,
The pressure control valve 12 maintains the opening degree of the through hole 40b' at the above-mentioned state, and the oil pressure Pc of the oil passage 7d continues to be maintained at the above-mentioned low constant level. Therefore, when increasing the relative angle to obtain a large output oil pressure Pp, the oil pressure Pc of the reaction piston side chamber 6
The handle torque T determined by the torsion angle and the torsion angle of the torsion bar 22 does not become large (see A in FIG. 27). During the above-mentioned stationary shutoff, even though the oil pressure Pc in the oil passage 7d is low as described above, the spool 51 (see Fig. 21) is lowered, so the orifice c is blocked and the oil pressure in the oil passage 7e is lowered. Hydraulic oil does not flow. Therefore, the pressure in the pilot oil passage _7e1 is:
The pressure becomes the same as Pc, and due to this pressure, the change-over valve 11 overcomes the elasticity of the spring 33, opens the bypass oil passage 7b, and is held at the L position in FIG. 1. Note that FIG. 1 shows the H position.

Further, when the automobile enters a low-speed driving state, the control device 15 receives a pulse signal from the vehicle speed sensor 14 and generates a current corresponding to the vehicle speed at that time, for example, i=
A current of 0.8 is sent to the solenoid valve 13, the plunger 52 and the spool 51 are raised from the lower limit position by a distance corresponding to the current value (moved to the right in FIG. 1), and the sleeve 5 shown in FIG.
The opening amount of the 0-side oil passage 50a is reduced. At this time, the oil passage 50b on the orifice c (sleeve 50 side) is still blocked, and due to the decrease in the opening amount of the oil passage 50a, the flow rate Q ₃ (Q ₄
is almost zero in this state) is the oil path 5 when the vehicle is stopped.
The flow rate decreases from the flow rate from 0a. Note that this decrease corresponds to the flow rate _Q5 from orifice e to low pressure oil passage 8b.
increases and absorbs. As described above, since the flow rate Q ₃ (Q ₄ ≒0) leaving the solenoid valve 13 is smaller than the flow rate Q ₃ from the oil passage 50a when the vehicle is stopped,
The oil pressure in the oil passage 7f on the upstream side of the orifice d is lower than when the vehicle is stopped. If you start turning the steering wheel to the right (or left) at low speeds above, the oil pressure Pc in oil passage 7d
begins to rise. Then, the oil pressure in the oil passage 7f also increases. This oil pressure is directly transmitted to the spool 41 (the small diameter end of the spool 41) of the pressure control valve 12 via the main pilot oil passage _7f1 , and the spool 41 is pushed in the direction of the arrow in FIG. At the same time, the hydraulic oil passing through the annular groove 41b of the spool 41 pushes the spool 41 in the direction of the arrow in FIG. 10 due to the difference in pressure receiving area. On the other hand, the spring 44 side communicates with the low pressure oil passage 8b, and the spool 41 resists the spring 44 and gradually rises (moves in the L direction in FIG. 1), and the through hole 40
The opening degree of b' gradually decreases, and when the hydraulic pressure pushing in the direction of the arrow above and the spring force are balanced, the spool 41 stops. However, the hydraulic pressure pushing the small diameter end of the spool 41 is lower than when the spool 41 is stopped, and the spool 4
The amount of rise of 1 is that much smaller (through hole 40
The opening amount of b' is correspondingly larger), and the oil pressure Pc of the oil passage 7d (reaction piston side chamber 6) becomes higher than when the vehicle is stopped. This state remains the same from then on, and if you cut the bundle further to the right (or left),
Even if the oil pressure Pp of the oil passages 7a, 7b, and 7c further increases, the pressure control valve 12 maintains the opening degree of the through hole 40b' in the above state, and the oil pressure Pc of the oil passage 7d continues to be higher than when the oil is stopped. held at a constant level.
Therefore, when increasing the relative angle to obtain a large output oil pressure Pp, the handle torque T becomes larger than when the vehicle is stopped, but it does not become as large as when the vehicle is at high speed, which will be described later.

Further, when the vehicle enters a high speed state at a predetermined speed, the control device 15 receives a pulse signal from the vehicle speed sensor 14, and sends a current of i=0 (see FIG. 29) to the solenoid valve 13, and the plunger 52 and spool 51 is raised to the upper limit position by the spring 60 (moved to the H position shown in FIG. 1), and only the orifice c shown in FIG.
It communicates with the oil passage 7f on the upstream side. At this time, orifice c is fully opened and the flow rate of orifice c is
Although Q ₄ increases, it increases only slightly compared to the above-mentioned low speed. On the other hand, since the flow rate Q ₃ of the oil passage 50a becomes almost zero, the flow rate of this system becomes the lowest. Note that this decrease is absorbed by further increasing the flow rate _Q5 from the orifice e to the low pressure oil passage 8b.
As described above, since the flow rate leaving the solenoid valve 13 decreases the most, the oil pressure in the oil passage 7f on the upstream side of the orifice d becomes the lowest. If you start turning the steering wheel to the right (or left) at higher speeds, oil path 7d
The hydraulic pressure PC starts to rise. Then, oil path 7
The oil pressure of f also increases. However, since the oil passage 50a is blocked, the amount of increase is extremely small. This oil pressure is directly transmitted to the spool 41 (the small diameter end of the spool 41) of the pressure control valve 12 via the main pilot oil passage _7f1 , and the spool 41 is pushed in the direction of the arrow in FIG. At the same time spool 4
The hydraulic oil passing through the annular groove 41b pushes the spool 41 in the direction of the arrow in FIG. 10 due to the difference in pressure receiving area. On the other hand, the spring 44 side communicates with the low pressure oil passage 8b, and the spool 41 gradually rises against the spring 44 (the first
(in the figure, the spool 41 moves in the L direction), the opening degree of the through hole 40b' gradually becomes smaller, and when the hydraulic pressure pushing in the direction of the arrow and the spring force are balanced, the spool 41 stops. However, the hydraulic pressure pushing the small diameter end of the spool 41 is the lowest, the amount of rise of the spool 41 is very small (the opening amount of the through hole 40' is the maximum), and the hydraulic pressure of the oil passage 7d (reaction piston side chamber 6) is the lowest. PC is the highest. On the other hand, since the orifice c opens into the oil passage 51a, the pressure in the oil passage 7e between the orifices b and c decreases, and this is transmitted to the spool 30 of the change-over valve 11 via the pilot oil passage _7e1 . The spool 30 descends (in Figure 1, H
position), the bypass oil passage 7b is closed,
Hydraulic oil from the oil pump 1 is sent to the oil passage switching valve 2 via the orifice a, and the output oil pressure Pp increases by the set pressure. This means that even when not steering at high speed (steering wheel in neutral position), oil passages 7a and 7
This means that the oil pressure Pp of the cylinders b and 7c is higher than when the vehicle is stopped or at low speed (see Pp ₁ in Fig. 27), and this oil pressure is transferred to the reaction piston side via the pressure control valve 12 and the oil passages 7d and 7d ₂ . This was communicated to Chamber 6,
Improves the feeling of reaction force (response) during minute steering at high speeds. As mentioned above, if you continue to turn the steering wheel further to the right (or left), the oil pressure Pp in the oil passages 7a, 7b, and 7c further increases, and the oil pressure Pc in the oil passage 7d further increases. When the oil pressure in the oil passage 7e between the two rises above the set value and the force acting on the spool ₃₀ via the pilot oil passage 7e1 becomes greater than the force of the spring 33, the spool 30 of the change-over valve 11 rises. (L position is selected in FIG. 1), and the bypass oil passage 7b is opened. Even in this state, if you continue to turn the steering wheel to the right (or left), the oil passages 7a, 7b,
Although the oil pressure Pp in the oil passage 7c further increases, the pressure control valve 12 maintains the opening degree of the through hole 40b' in the above state, and the oil pressure Pc in the oil passage 7d continues to be maintained at the highest constant level. Therefore, when increasing the relative angle to obtain a large output oil pressure Pp,
The handle torque T becomes larger (see B in FIG. 27).

As described above, the power steering device of the present invention transmits the movement of the steering wheel to the oil passage switching valve 2 via the torsion bar 22, and the high pressure oil passage 7a extending from the oil pump 1 to the oil passage switching valve 2 and the oil passage switching valve 2. The transmission oil passage 8a extending from the high pressure oil passage 7a to the oil tank 4 is switched to operate the power cylinder 3 in a predetermined steering direction, and a part of the hydraulic oil flowing through the same high pressure oil passage 7a is guided to the reaction piston 5 and the torsion bar 22 In the power steering device, parallel oil passages 7e, 7e' branched from the middle of oil passages 7b, 7c, and 7d extending from the high-pressure oil passage 7d to the reaction piston 5, and the same parallel oil passages. An orifice b provided in one of 7e and 7e' 7e, a flow control valve 13 that discharges hydraulic oil from the parallel oil passage proportionally according to the vehicle speed, and a flow control valve 13 that discharges hydraulic oil from the parallel oil passage in proportion to the vehicle speed, and a Orifice d that generates pilot pressure
and a pressure control valve 12 which is operated by the pilot pressure to control the oil pressure in the oil passage 7d to the reaction piston 5 to be constant and to increase as the speed increases. The hydraulic pressure on the piston 5 is minimized. Therefore, the oil passage switching valve 2 can be moved with a small amount of steering force (handle torque) during stationary turning. Furthermore, as the vehicle speed increases, the oil pressure applied to the reaction piston 5 increases. Therefore, the oil passage switching valve 2 must be moved with a relatively large steering force at high speeds, and an appropriate response (feeling of reaction force) can be obtained at high speeds. In addition, since the output oil pressure (pump discharge pressure) Pp is guided to the reaction piston 5 via the pressure control valve 12, the output oil pressure Pp varies with respect to the steering wheel torque T in the steering range during driving, as shown in Fig. 27B. Shows linear characteristics. Therefore, there is no feeling of entanglement during steering, which is found in ordinary power steering devices, and the steering is extremely stable during driving, and the steering matches the steering feel.

In addition, in the present invention, the flow rate control valve 13
However, the plunger 52 and the spring 60 that biases the plunger 52 in the direction of the high speed position
an electromagnetic coil 57 that operates the spool 51 loosely around the plunger 52 against the biasing force of a spring, and a tightening fixing member 54 that tightens and fixes the spool 51 to the plunger 52.
and a sleeve 50 slidably and fluid-tightly disposed around the spool 51, thereby achieving the following effects. That is, finishing accuracy on the order of microns is required between the sleeve 50 and the spool 51. On the other hand, the plunger 52 is assembled to the casing 20 via some parts on the electromagnetic coil 57 side of the flow control valve 13. Therefore, it is practically impossible to match the axis of the plunger 52 with the axis of the spool 51 within the above precision range, but in this case, the spool 51 is loosely fitted into the plunger 52, and there is a slight gap between them. There is a gap of
The deviation caused by the assembly on the plunger 52 side is absorbed by this gap and is not transmitted to the spool 51, and the sleeve 50 and spool 51 are maintained in the finished state. Therefore, the electromagnetic coil 57
This also has the effect of smoothing the operation of the flow rate control valve 13 having the plunger 52.

Note that the plunger 5 is press-fitted into the member 53 made of magnetic material.
2 is made of a non-magnetic material, even if there are foreign objects such as iron powder in the hydraulic oil, they will not be adsorbed to the oil passage inside the plunger 52, and from this point of view as well, the operation of the flow control valve 13 will be made smoother. Ru.

[Brief explanation of the drawing]

Fig. 1 is a hydraulic circuit diagram showing an embodiment of the power steering device according to the present invention, Fig. 2 is a longitudinal cross-sectional side view of the oil passage switching valve, Fig. 3 is a lower cross-sectional plan view thereof, and Fig. 4 is an upper cross-sectional view thereof. The plan view and Figure 5 are
Figure 6 is a vertical cross-sectional side view of the over valve, pressure control valve, and solenoid valve, Figure 6 is a vertical cross-sectional side view of the oil passage switching valve and pressure control valve, and Figure 7 is the oil passage switching valve and change over valve. Fig. 8 is an enlarged longitudinal sectional side view of the changeover valve, pressure control valve, and solenoid valve, Fig. 8 is an end view of the solenoid valve, and Fig. 9 is an enlarged view of the pressure control valve. Longitudinal side view, 1st
Fig. 0 is an enlarged longitudinal and other side view thereof, Fig. 11 is an enlarged plan view of the sleeve of the pressure control valve, Fig. 12 is an enlarged longitudinal one side view thereof, Fig. 13 is an enlarged longitudinal and other side view thereof, and Fig. 14 is an enlarged longitudinal and other side view thereof. Fig. 12 is a cross-sectional plan view along the arrow line, Fig. 15 is a cross-sectional view taken from the arrow line in Fig. 13.
16 is a cross-sectional plan view taken along the line shown in FIG. 12, and FIG. 17 is a cross-sectional plan view taken along the line shown in FIG.
Figure 8 is a side view of the sleeve of the same pressure control valve.
FIG. 19 is a longitudinal side view showing the sleeve and spool, FIG. 20 is a side view showing the spool,
Fig. 21 is an enlarged longitudinal sectional side view of the sleeve and spool of the solenoid valve, Fig. 22 is a transverse plan view of the filter, Fig. 23 is a front view thereof, Fig. 24 is a transverse plan view showing its installed state, and Fig. 25 The figure is a circuit diagram of the control device, and Figure 26 shows the output oil pressure of the oil passage switching valve (pump discharge pressure) and the torsion angle of the torsion bar (relative angle between the spool and sleeve of the oil passage switching valve).
FIG. 27 is an explanatory diagram showing the relationship between output oil pressure and handle torque. FIG. 28 is an explanatory diagram showing the relationship between reaction force plunger side chamber oil pressure (handle torque) and torsion bar torsion angle. Fig. 29 is an explanatory diagram showing the relationship between the oil pressure of the reaction force plunger side chamber and the output oil pressure, Fig. 30
FIG. 31 is an explanatory diagram showing the relationship between the handle torque and the torsion angle of the torsion bar, and FIG. 31 is an explanatory diagram showing the flow rate at the control system inlet side and the flow rate at each part within the control system. 1...Oil pump, 2...Oil passage switching valve, 3...
...Power cylinder, 4...Oil tank, 5...
Reaction piston, 7a...high pressure oil path, 7b, 7c,
7d... Oil passage extending from the high pressure oil passage 7a to the reaction piston 5, 7e... Parallel oil passage, 8a, 8b... Low pressure oil passage, 12... Pressure control valve, 13... Flow rate control valve, 50... ...Sleeve, 51...Spool, 52
... Plunger, 54 ... Tightening fixing member, 57
...Electromagnetic coil, 60...Spring, a, b, c,
d, e...orifice.

Claims (1)

[Scope of utility model registration request] The power cylinder is operated by transmitting the movement of the handle to the oil passage switching valve via the torsion bar to switch between the high pressure oil passage extending from the oil pump to the oil passage switching valve and the low pressure oil passage extending from the oil passage switching valve to the oil tank. In a power steering device that operates in a predetermined steering direction and controls torsion of a torsion bar by guiding a portion of hydraulic oil flowing through the high-pressure oil passage to a reaction piston, the oil extends from the high-pressure oil passage to the reaction piston. A parallel oil path branching from the middle of the road, an orifice installed on one side of the parallel oil path, a flow control valve that discharges hydraulic oil from the parallel oil path proportionally according to vehicle speed, and a flow rate control valve. An orifice that generates a pilot pressure according to the flow rate on the downstream side of the valve, and a pressure control valve that is operated by the pilot pressure to control the oil pressure in the oil path to the reaction piston to be constant and to increase as the speed increases. The flow control valve includes a plunger, a spring that biases the plunger toward the high speed position, an electromagnetic coil that operates the plunger toward the low speed position against the biasing force of the spring, and an electromagnetic coil surrounding the plunger. A power steering device comprising: a spool that is loosely fitted into the plunger; a tightening and fixing member that tightens and fixes the spool to the plunger; and a sleeve slidably and fluid-tightly disposed around the spool. .