JPH0214538Y2 - - Google Patents

Description

[Detailed explanation 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 extending from the oil pump to the oil passage switching valve and a low pressure oil passage extending from the oil passage switching valve to the oil tank. In the power steering device, the power cylinder is actuated in a predetermined steering direction by separating the oil passage from the high-pressure oil passage, and a part of the hydraulic oil flowing in the same high-pressure oil passage is guided to the reaction piston to restrict torsion of the torsion bar. A parallel oil passage branched from the middle of the oil passage extending from the passageway to the reaction 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 for discharging, an orifice that generates a pilot pressure according to the flow rate on the downstream side of the flow rate control valve, and an orifice that is operated by the pilot pressure to maintain a constant hydraulic pressure in the oil passage to the reaction piston at high speed. a pressure control valve that controls the pressure so that the pressure increases as high as possible, the pressure control valve having a sleeve 40 and a spool 41;
On the outer circumferential surface of the sleeve 40, there is a notch 40b that communicates with the most upstream side of the oil passage extending from the high-pressure oil passage to the reaction piston, and a notch 40d that communicates with the port 40b' and one of the parallel oil passages 7e. and a notch 40 that communicates with the orifice b and the reaction piston side.
e, a port 40e', a connecting notch 40c, and ports 40c', 40c'', and the spool 41
Annular passages 41a and 41b, which are independent from each other, are formed on the outer peripheral surface of the sleeve 40, and the orifice b and the port 40e' are connected to the annular passage 41b, the port 40c' and the annular passage 41a, and the port 40c. '' and the annular passage 41b, and the port 40b' and the annular passage 41a are communicated or cut off by movement of the spool 41. The present invention provides an improved power steering device that can be lightly steered at times and provides a moderate response (feeling of reaction force) at high speeds.Another object is to provide an improved power steering device that allows for a compact oil passage configuration.

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).The oil pump 1 has a constant flow rate (about 7/min) and a variable discharge pressure (5 kg/min). cm ² - 70Kg/cm ² ) oil pump. In addition, 2 is a four-way oil passage switching valve (rotary valve), 3 is a power cylinder for steering,
4 is an oil tank, 5 is a plurality of reaction pistons,
6 is a chamber formed behind each reaction force piston 5, 7a is a high pressure oil passage extending from the oil pump 1 to the oil passage switching valve 2, and 8a is the oil passage switching valve 2.
a low pressure oil passage extending from 9 to the oil tank 4;
a and 10a are oil passages extending from the oil passage switching valve 2 to the power cylinder 3, a is an orifice provided in the middle of the high-pressure oil passage 7a, and 7b is the orifice a.
11 is a change-over valve interposed in the middle of the bypass oil passage 7b, and 12 is an upper layer of the change-over valve 11. Oil path 7b
13 is a flow rate control valve (hereinafter referred to as a solenoid valve), and 7d is an oil path extending from the pressure control valve 12, which is connected to the pressure control valve 12 via an oil passage 7c. Parallel oil passages 7e and 7e' branch from the passage 7d and extend to the solenoid valve 13. Also, 7d ₁ is the oil passage 7d
7d ₂ is a pilot oil passage that extends from the middle of the oil passage 7d to the chamber 6 behind the reaction piston 5, and 7d ₃ is an oil passage that extends from the middle of the oil passage 7d to the chamber 6 behind the reaction piston 5. to low pressure oil passage 8b
_7e1 is pilot oil extending from the oil path 7e between the orifices b and c to the change-over valve 11. road, e is the oil road 7d ₃
7f is an oil passage extending from the solenoid valve 13 to the low pressure oil passage 8b; d is an orifice provided in the middle of the oil passage 7f;
7f ₁ is a main pilot oil passage extending from the oil passage 7f on the upstream side of the orifice d to the pressure control valve 12, 14 is a vehicle speed sensor, 15 is a control device, 16
is an ignition switch, 17 is an ignition coil, and wiring extends from 18a and 18b to the electromagnetic coil of the solenoid valve 13.The vehicle speed sensor 14 detects the vehicle speed and outputs a pulse signal (depending on the vehicle speed). The control device 15 also sends a pulse signal (pulse signal) to the control device 15.
Current corresponding to the same pulse signal (from zero current at high speed (i=0) to maximum current at stop (i=1)
A current (corresponding to the vehicle speed up to) is sent to the electromagnetic coil 57 of the solenoid valve 13 to hold the plunger 52 and spool 51 of the solenoid valve 13 at a predetermined position corresponding to the 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. Reference numeral 20 in FIGS. 2 to 7 is a valve housing, and each of the above-mentioned valves 2, 11, 12, and 13 is incorporated into the 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. The cylinder block 22 is a torsion bar inserted into the input shaft 21, and the torsion bar 22 is
The upper part of the input shaft 21 is fixed to the upper part of the input shaft 21, and the lower part thereof is fixed to the cylinder block 23. Further, reference numeral 21a denotes a plurality of vertical grooves provided on the outer peripheral surface of the lower part of the input shaft 21, and a plurality of vertical grooves 21a are provided on the outer circumferential surface of the lower part of the input shaft 21.
3 is provided with a cylinder facing each of the longitudinal grooves 21a, the reaction piston 5 is fitted into each cylinder, and a protrusion provided at the tip of each reaction piston 5 is inserted into each of the longitudinal grooves 21a. 21a. The chamber 6 behind each reaction 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, 24a is a rack meshed with the pinion 23a, 24 is a rack support, 26 is a cap, and 25 is the same cap 2.
6 and the rack support 24, 28 is the sleeve of the oil passage switching valve 2 fixed in the valve housing 20 directly above the cylinder block 23, and 28a, 28b, 28c are the outer periphery of the sleeve 28. Oil passage provided on the surface, 27 is the same sleeve 2
8 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; 27a, 27b, and 27c are the outer peripheral surfaces of the valve body 27; When the handle is in the neutral position, the high pressure oil passage 7a is connected to the chamber 29 between the input shaft 21 and the torsion bar 22 via the oil passage 27a of the valve body 27 and the oil passage 28a of the sleeve 28. The hydraulic oil from the oil pump 1 is in communication with the high pressure oil passage 7a → oil passage 28a → oil passage 2.
7a → Chamber 29 (the oil passage between oil passage 27a and chamber 29 is not shown) → Low pressure oil passage 8
When the input shaft 21 is rotated to the right relative to the valve body 27 by turning the handle to the right so that the circulation is from a → oil tank 4 → oil pump 1, the high pressure oil passage 7a is connected to the oil passage 27 of the valve body 27.
A, 27b and the oil passage 28b of the sleeve 28 to the oil passage 9a of the power cylinder 3, and the low pressure oil passage 8a
is the oil passage 27 between the chamber 29 and the valve body 27.
c and the oil passage 10a of the power cylinder 3 via the oil passage 28c of the sleeve 28,
Hydraulic oil is sent from the oil pump 1 to the left chamber of the power cylinder 3 through the high-pressure oil passage 7a → oil passage 27a → oil passage 28b → oil passage 9a → oil passage 3, while the oil in the right chamber of the power cylinder 3 is sent from the oil passage 10a → oil passage 28c→Oil path 27c→
Chamber 29→Low pressure oil passage 8a→Return to tank 4, the piston rod of power cylinder 3 moves to the right, and by turning the steering wheel to the left, the input shaft 21 is moved to the valve body 27. When the high-pressure oil passage 7a rotates to the left relative to
The low pressure oil passage 8a is connected to the oil passage 10a in the chamber 29.
and the oil passage 27b of the valve body 27 and the sleeve 28
The hydraulic oil from the oil pump 1 is connected to the oil passage 9a of the power cylinder 3 via the oil passage 28b of the high pressure oil passage 7a → oil passage 27a → oil passage 28.
c→Oil passage 10a→Oil in the left chamber of the power cylinder 3 is sent to the right chamber of the power cylinder 3, while oil in the left chamber of the power cylinder 3 is sent to the oil passage 9.
a → Oil passage 28b → Oil passage 27b → Chamber 29 →
The low-pressure oil passage 8a is returned to the tank 4, and the piston rod of the power cylinder 3 moves to the left, thereby performing leftward steering. Next, to explain the change over valve 11 in detail, the change over valve 11 has the fourth,
As is clear from FIG. 7, it is interposed in the middle of the bypass oil passage 7b of the orifice a. The change-over valve 11 includes a spool 30 (the spool 30 is shown in a high-speed position) having an annular groove 30a (the annular groove 30a is a part of the oil passage 7b), a cap 31, and these spools 30. The spool 30 has a spring 33 and an O-ring 34 interposed between the spring 33 and the cap 31. When the oil pressure in the pilot oil passage _7e1 (see Fig. 1) increases, the spool 30
When the hydraulic pressure in the pilot oil passage _7e1 decreases so as to open the bypass oil passage 7b, the spool 30 is moved backward by the spring 33, thereby closing the bypass oil passage 7b. Next, to explain the pressure control valve 12 in detail, the pressure control valve 12 consists of a sleeve 40, a spool 41 and a cap 42, as is clear from FIGS. 5, 6 and 7.
and the stopper 43, and the spring 44 and the spool 41 interposed between the spool 41 and the stopper 43.
It has a member 45 having an orifice d fixed therein. Further, the spool 41 has the ninth, tenth,
As shown in Figures 19 and 20, three annular grooves 41a,
41b and 41c are provided, and the annular groove 41a is connected to the change over valve 1 of the bypass oil passage 7b.
It faces an oil passage 7c branched from the upstream side of 1.
Also, 41d is connected to the same spool 4 from the orifice d.
A chamber 41e extending upward within 1 is an oil passage connecting the chamber 41d and the annular groove 41c (these 41d, 41e, 41c are part of the low pressure oil passage 8b), and the annular groove 41c is A pressure transmission oil passage 8 on the valve housing 20 side extends obliquely downward as shown in Fig. 6 from a low pressure oil passage 8b formed directly above the valve body 27 of the oil passage switching valve 2 shown in Fig. 2.
facing b. Further, the annular groove 41a communicates with the chamber 41d via an orifice e. Further, as shown in FIGS. 11 to 17, the sleeve 40 has a notch 40a having a through hole 40a' and a through hole 40b' from the top to the bottom with different phases in the circumferential direction on the outer circumferential surface. Motsu notch 40b
A notch 40c having through holes 40c' and 40c'', a notch 40d having an orifice b, and a notch 40e having a through hole 40e' are provided. Connect with the low pressure oil passage 8b on the valve housing 20 side,
The notch 40b having the through hole 40b' is the spool 41.
The annular groove 41a of the spool 41 connects the oil passage 7c on the valve housing 20 side, and the notch 40c with through holes 40c', 40c'' connects the annular groove 41a of the spool 41 with the oil passage 7c of the valve housing 20 side.
b, the notch 40d with the orifice b connects the annular groove 41b of the spool 41 and the oil passage 7e on the valve housing 20 side, and the notch 40e with the through hole 40e' connects the annular groove 41b of the spool 41 with the third oil passage 7e. , connect the oil passage 7d on the valve housing 20 side shown in Figure 5, and connect the spool 4 from the orifice d.
From the bypass oil passage 7b so that the oil discharged to the chamber 41d of No. 1 returns to the oil tank 4 via the oil passage 41e → the annular groove 41c → the through hole 40a' → the notch 40a → the low pressure oil passage 8b on the valve housing 20 side. The hydraulic oil that has entered the notch 40b via the oil passage 7c flows through the through hole 40b' → annular groove 41a → notch 40c → through hole 40c'' → annular groove 41b → through hole 40e' → notch 4
A part of the hydraulic oil flowing in the annular groove 41b is directed to the solenoid valve 13 and the reaction piston 5 via the oil passage 7d of the valve housing 20, and also flows through the orifice b→cutout 40d→valve housing 20. Acts as a pilot pressure behind the spool 30 of the change-over valve 11 through the side oil passage 7e (see 7e ₁ in FIG. 5),
Furthermore, an oil passage 30 provided at the rear end of the spool 30
b (see FIG. 7) → toward the solenoid valve 13 via the oil passage 7e on the valve housing 20 side. Next, the solenoid valve 1
To specifically explain 3, the solenoid valve 1
3 are disposed directly below the pressure control valve 12 so that their axes coincide with each other, as is clear from FIGS. 5, 8, and 21. The solenoid valve 13 includes 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. A back-up spring 56 and an electromagnetic coil 57 interposed between the seat plate 55 and the sleeve 50 that come into contact with the sleeve 40 of No. 12, and a nut 58 fixed to the casing on the side of the electromagnetic coil 57. It has a plunger pressing force adjustment bolt 59 screwed into the sleeve, a spring 60 interposed between the bolt 59 and the plunger 52, and a lock nut 61 for tightening and fixing the assembly of the solenoid valve 13 to the valve housing 20. 50, as shown in FIG. 21, has an oil path 50a communicating with the oil path 7d on the valve housing 20 side (see FIG. 5) and an oil path 50b communicating with the oil path 7e on the valve housing 20 side. , an orifice c is provided in the oil passage 50b. Further, the spool 51 has a diagonal groove 51.
The plunger 52 has an oil passage 52a, a through hole 52b, and an axial oil passage 52c communicating with the through hole 51b.
are provided for each. As already mentioned, the hydraulic oil flowing toward the solenoid valve 13 through the oil passage 7d on the valve housing 20 side shown in FIG.
The solenoid valve 1 enters the oil passage 50a shown in Fig. 1, and the oil passage 7e on the valve housing 20 side shown in Fig. 5.
3 enters the oil passage 50b 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 → Orifice d via oil passage 52c
It will face the side member 45. Also, when high speed → low speed, the spool 51 descends and the orifice e
While the opening amount of the oil passage 50a is increased, only the oil passage 50a is opened when the vehicle is stopped. In FIG. 1, Q ₀ is the flow rate on the discharge side of the oil pump 1, Q ₁ is the oil amount in the high pressure oil passage 7a, Q ₂ is the flow rate in the oil passage 7c, Q ₃ is the flow rate in the oil passage 7d (the flow rate in the oil passage 50a,
Q ₄ indicates the flow rate downstream of orifice c, Q ₅ indicates the flow rate downstream of orifice e, and Q ₁ :Q ₂ is 6:
It is about 1. Moreover, the flow rate Q ₂ of the oil passage 7c is Q ₂ =
Q ₃ +Q ₄ +Q ₅ (see Figure 30). Further, the diameter of the sleeve 50 of the solenoid valve 13 is different in the upper, middle, and lower parts as shown in FIG. 21, and the diameter is smaller as the upper part becomes smaller, and there is a difference of D ₁ and D ₂ between them. 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 together with the O-ring 62 into the sleeve 50, thereby 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 consists of a frame body 71 and a wire mesh 72, and has a notch 40b (9th, 13th) provided in the sleeve 40 of the pressure control valve 12.
(see figure), that is, it is fitted into the entrance of the control system oil passage,
Prevents foreign matter such as dust from entering the control system oil path. Note that foreign matter such as dust should not enter the control system oil path.
A filter of this type may be provided at the inlet of the high pressure oil passage 7a provided in the valve casing 20 (see the arrow in Figure 4), but in that case, the entire discharge flow rate of the pump passes through the filter. The filter needs to be large, and it is difficult to store the filter in the space shown. The entrance of the high-pressure oil passage 7a is made larger by inserting a drill into the orifice a and oil passage 7b, which are branched into two directions.
This is to make it easier to process and at the same time to make it easier to connect with piping (not shown). In addition, other oil passages 7b (change over)
Oil passages 7b, 7c, 7d, 7e on the downstream side of the valve 11
As can be seen from FIGS. 3, 4, and 5, the holes are formed by drilling and plugging holes in the valve housing 20 in the vertical and horizontal directions, which also facilitates the machining of the oil passage. In addition, 2nd, 3rd, 4th, 6th, 7th
Z in the figure is the central axis of the oil passage switching valve 2, and in Figures 2 and 5,
Z ₁ is the center of the pinion 23a. Further, an example of the control device 15 is shown in FIG. 25. 80 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 amplification circuit,
38 is a transistor, 84 is a reset circuit that resets the timer circuit 87 when the vehicle speed is other than zero, and 85 is a pulse/voltage conversion circuit that sends out a voltage proportional to the engine rotation speed, 86 is an engine rotation The engine speed setting circuit 88 starts the timer circuit 87 when the engine speed is 2000 rpm or more and turns it off when the engine speed is 2000 rpm or less.
Vehicle speed input disconnection detection circuit in ON state, 89 is a transistor, 90 is a relay, 91 is a negative feedback circuit that stabilizes the current flowing to the electromagnetic coil 57 of the solenoid valve 13, when the vehicle speed is zero and the engine rotation speed is 2000 rpm or more. is normally not possible. Therefore, this condition is normally not possible. Therefore, if this condition continues for more than 5 to 10 seconds, 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).
Turn on relay 90 and turn on solenoid valve 13.
(The power supply to the electromagnetic coil 57 is stopped. Therefore, according to this control circuit, when a failure occurs, the solenoid valve 1
3 is de-energized, the steering wheel becomes difficult to operate at high speeds (it has a phase-safe function), and it 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
(discharge pressure) P _p of the valve body 20 of the input shaft 21 when the handle is turned 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 P _p of the oil pump 1 is
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 P _c of the same oil passage 7d rises in the same way. At this time, if the car 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
and lower the spool 51 to the lower limit position (first
In the figure, the oil passage 50 in Figure 21 is moved to the L position).
Only a is connected to the oil passages 51a, 51b on the spool 51 side,
Oil passage 7f on the upstream side of orifice d via 52b
The oil pressure in the oil passage 7f is set to the same value as the oil pressure P _c in the oil passage 7d. If you start turning the steering wheel to the right (or left) during a stop above, the oil pressure in oil passage 7d P _c
begins to rise. Then, the oil pressure in the oil passage 7f also increases by the same value. This oil pressure is applied to the main pilot oil line 7.
The force is directly transmitted to the spool 41 (the small diameter end of the spool 41) of the pressure control valve 12 via _f1 , 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 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 through hole 40
The opening degree of b' is the smallest, and the oil pressure P _c of the oil passage 7d (reaction piston side chamber 6) is the lowest. This state remains the same from then on, and even if the handle is turned further to the right (or left) and the oil pressure P _p in the oil passages 7a, 7b, and 7c further increases, the pressure control valve 1
2 maintains the opening degree of the through hole 40b' in the above state,
The oil pressure P _c of the oil passage 7d is continuously maintained at the above-mentioned low constant level. Therefore, when increasing the relative angle to obtain a large output oil pressure P _p , the oil pressure P _c of the reaction piston side chamber 6 and the torsion bar 2
The hand torque T determined by the twist angle of 2 does not become large (see A in Fig. 27). During the above-mentioned stationary shutoff, even though the oil pressure P _c in the oil passage 7d is low as described above, the spool 51 (see Fig. 21)
Since the is lowered, the orifice c is blocked and the hydraulic oil does not flow into the oil passage 7e. Therefore, the pressure in the pilot oil passage _7e1 is the same as P _c , but
This pressure causes changeover valve 11
overcomes the elasticity of the spring 33, opens the bypass oil passage 7b, and is held at the L position in FIG. 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 high 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 in oil passage 7d P _c
begins to rise. Then, the oil pressure in the oil passage 7f also increases. This oil pressure is directly transmitted to the spool 11 (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.
The amount of rise is correspondingly smaller (the opening amount of the through hole 40b' is correspondingly larger), and the oil pressure P _c of the oil passage 7d (reaction piston side chamber 6) is higher than when the vehicle is stopped. This condition remains the same from then on, and by turning the steering wheel further to the right (or left), oil passage 7a,
Even if the oil pressure P _p of the oil passages 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 P _c of the oil passage 7d continues to be at a constant level higher than when the vehicle is stopped. is maintained. Therefore, when increasing the relative angle to obtain a large output oil pressure P _p , 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 passage 7 on the upstream side of the orifice d
The oil pressure at f is the lowest. When the steering wheel starts to be turned to the right (or left) at higher speeds, the oil pressure P _c in the oil passage 7d starts to rise. Then, the oil pressure in the oil passage 7f 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, 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 is connected to the low pressure oil passage 8b, and the spool 4
1 gradually rises against the spring 44 (in Fig. 1, L
The opening of the through hole 40b' gradually decreases, 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 oil passage 7d (reaction piston side chamber 6) is Hydraulic pressure P _c becomes highest. On the other hand, since the orifice c opens into the oil passage 51a, the reaction force 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 is lowered (the H position is selected in Fig. 1), the bypass oil passage 7b is closed, and the hydraulic oil from the oil pump 1 is sent to the oil passage switching valve 2 through the orifice a, and the output is Oil pressure P _p increases by the set pressure. This means that even when the steering is not performed at high speed (huddling neutral position), the oil passages 7a and 7
This means that the oil pressure P _p of the cylinders b and 7c is higher than when the vehicle is stopped or at low speed (see P _p1 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 _7d2 . The reaction force is transmitted to the chamber 6, and the feeling of reaction force (response) during minute steering at high speeds is improved. As mentioned above, if you continue to turn the steering wheel further to the right (or left), the oil pressure P _p in the oil passages 7a, 7b, and 7c further increases, and the oil pressure P _c in the oil passage 7d further increases. , c oil passage 7
The oil pressure of e increases above the set value, and the force acting on the spool 30 via the pilot oil passage _7e1 is applied to the spring 3.
When the force becomes larger than 3, changeover occurs.
The spool 30 of the valve 11 is raised (the 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 pressure in the oil passages 7a, 7b, and 7c will increase.
Although P _p continues to rise, pressure control valve 1
2 maintains the opening degree of the through hole 40b' in the above state,
The oil pressure P _c of the oil passage 7d continues to be maintained at the highest constant level. Therefore, by increasing the relative angle,
When a large output oil pressure P _p is obtained, the handle torque T becomes large (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 and 7e' branched from the middle of oil passages 7b, 7c, and 7d extending from the high-pressure oil passage 7a to the reaction piston 5; 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) P _p is guided to the reaction piston 5 via the pressure control valve 12, the output oil pressure P _p changes 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 matches the steering feel.

In addition, in the present invention, the pressure control valve 12 has a sleeve 40 and a spool 41.
0, a notch 40 communicating with the most upstream side of the oil passage extending from the high-pressure oil passage to the reaction piston.
b, a notch 40d communicating with port 40b' and one side 7e of the parallel oil passage, a notch 40e communicating with orifice b and the reaction piston side, port 40e', connecting notch 40c and port 40c',
40c'' on the outer peripheral surface of the spool 41,
Mutually independent annular passages 41a and 41b formed by the inner peripheral surface of the sleeve 40 are provided, and the orifice b, the port 40e' and the annular passage 41b, the port 40c' and the annular passage 41a, and the port 40c'' and the annular passage 41b. In addition to communicating with each other, port 4
0b' and the annular passage 41a are communicated with or interrupted by movement of the spool 41, which has the effect of making the structure of the oil passage compact.

[Brief explanation of drawings]

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. 10 is an enlarged perspective view of the sleeve of the pressure control valve; FIG. 11 is an enlarged plan view of the sleeve of the pressure control valve; FIG. 12 is an enlarged perspective view of the sleeve of the pressure control valve;
The figure is an enlarged longitudinal sectional side view, FIG. 13 is an enlarged longitudinal sectional side view, and FIG.
15 is a cross-sectional plan view taken along the line, FIG. 15 is a cross-sectional plan view taken along the arrow line in FIG. 13, and FIG.
Fig. 2 Arrow view - cross-sectional plan view along the line, No. 17
The figures are a cross-sectional plan view along the arrow line in FIG. 13, FIG. 18 is a side view of the sleeve of the pressure control valve, FIG. 19 is a vertical side view showing the sleeve and spool, and FIG. 20 is the same side view. A side view showing the spool, Fig. 21 is an enlarged vertical sectional side view of the sleeve and spool of the solenoid valve, Fig. 22 is a cross-sectional plan view of the filter, Fig. 23 is a front view thereof, and Fig. 24 shows the state of the device. Cross-sectional plan, No. 25
The figure is a circuit diagram of the control device, and Figure 26 is an explanatory diagram showing the relationship between 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, and Fig. 29 is an explanatory diagram showing the relationship between reaction force plunger side chamber oil pressure (handle torque). An explanatory diagram showing the relationship between the hydraulic pressure of the force plunger side chamber and the output hydraulic pressure, Fig. 30 is an explanatory diagram showing the relationship between the handle torque and the torsion angle of the torsion bar, and Fig. 31 shows the flow rate at the control system inlet side and the inside of the control system. FIG. 3 is an explanatory diagram showing the flow rate of each part. 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, 40... ...Sleeve, 40b, 40c, 40
d, 40e...notch, 40b', 40c', 40
c″, 40e′...port, 41...spool, 41
a, 42b... annular groove, a, b, c, d... orifice.

Claims (1)

[Scope of utility model registration request] The movement of the handle is transmitted to the oil passage switching valve via the torsion bar, and 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 are connected to the power cylinder. In the power steering device, the torsion bar is actuated in a predetermined steering direction and a portion of the hydraulic oil flowing through the high pressure oil passage is guided to the reaction piston to restrict torsion of the torsion bar. A parallel oil path branching from the middle of the oil path, 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 An orifice that generates a pilot pressure according to the flow rate on the downstream side of the control valve, and a pressure control that is operated by the pilot pressure to control the oil pressure in the oil path to the reaction piston to be constant and increase as the speed increases. The pressure control valve has a sleeve 40 and a spool 41, and a notch in the outer peripheral surface of the sleeve 40 that communicates with the most upstream side of the oil passage extending from the high-pressure oil passage to the reaction piston. A notch 40d that communicates between the port 40b and the port 40b' and one 7e of the parallel oil passage, a notch 40e that communicates with the orifice b and the reaction piston side, and a connection notch 40c and the port 40e'.
0c', 40c'', and providing independent annular passages 41a, 41b on the outer circumferential surface of the spool 41 and the inner circumferential surface of the sleeve 40,
orifice b, port 40e' and annular passage 41b,
A power steering system characterized in that the port 40c' and the annular passage 41a are communicated with each other, and the port 40c'' and the annular passage 41b are communicated with each other, and the port 40b' and the annular passage 41a are communicated or cut off by movement of the spool 41. Device.