JPH0232545Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention transmits the movement of the handle to the oil passage switching valve via a torsion bar to switch between the high pressure oil passage and the low pressure oil passage extending from the oil pump to the oil passage switching valve, thereby controlling the power cylinder to a predetermined position. In a power steering device that operates in a steering direction and regulates torsion of a torsion bar by guiding a portion of hydraulic oil flowing through the high-pressure oil passage to a reaction piston, a branch oil extending 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 an orifice that is installed upstream of the branch part of the parallel oil passage in the branch oil passage and is actuated by the pilot pressure to apply pressure to the reaction piston. a pressure control valve that controls hydraulic pressure to be constant and to increase as the speed increases; It is characterized by comprising a solenoid that operates in the direction of a low speed position against a force, and a control device that supplies a large current to the solenoid at low speeds and a small current at high speeds, and its purpose is The steering wheel can be easily steered when turning stationary, and has a moderate response (feeling of reaction force) at high speeds.
You can get Another object of the present invention is to provide an improved power steering system that provides a fail-safe function at high speeds.

Next, the power steering device of the present invention will be explained with reference to an embodiment shown in FIGS. 1 to 25. First, the outline will be explained with reference to Fig. 1. 1 is an oil pump driven by an engine (not shown);
The oil pump 1 is an oil pump with a constant flow rate (about 7/min) and a variable discharge pressure (5 kg/cm ² to 70 kg/cm ² ). 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 pressure 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 the oil tank 4 to the oil tank 4, 9a,
10a is an oil passage 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 an oil passage 7a on the upstream and downstream sides of the orifice a. The connected bypass oil passage, 11, is a change-over valve inserted in the middle of the bypass oil passage 7b, and 12 is connected to the oil passage 7b on the upstream side of the change-over valve 11 via an oil passage 7c. A pressure control valve (hereinafter referred to as a pressure control valve), 13 a flow control valve (hereinafter referred to as a solenoid valve), 7d an oil passage extending from the pressure control valve 12, and a parallel oil passage branching from the oil passage 7d. 7e and 7e' 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, and 7d ₂ is an oil passage extending from the middle of the oil passage 7d to the chamber 6 behind the reaction piston 5.
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 between the orifices b and c. 7e to said change over valve 11
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 7d;
is an orifice provided in the middle of the oil passage 7f, and _7f1 is a main pilot oil passage extending from the oil passage 7f upstream of the orifice d to the pressure control valve 12;
is a vehicle speed sensor, 15 is a control device, 16 is an ignition switch, 17 is an ignition coil, and 18a and 18b are connected to the solenoid valve 1.
The vehicle speed sensor 14 detects the vehicle speed through the wiring extending to the electromagnetic coil No. 3, and sends the resulting pulse signal (pulse signal according to the vehicle speed) to the control device 1.
In addition, the control device 15 transmits a current corresponding to the pulse signal (corresponding to the vehicle speed from zero current at a predetermined high speed (i=0) to maximum current at a stop (i=1)). Solenoid valve 1
The plunger 52 and spool 51 of the solenoid valve 13 are held at predetermined positions according to the above-mentioned current value. Next, change over the oil passage switching valve 2.
The 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, the oil passage switching valve 2 will be explained in detail with reference to FIG.
1 is an input shaft operated by a handle (not shown), 23 in FIGS. 2 and 3 is a cylinder block rotatably supported within the valve housing 20 by upper and lower bearings, and 22 is inserted into the input shaft 21. The torsion bar 22 has its upper part fixed to the upper part of the input shaft 21 and its lower part fixed to the cylinder block 23, respectively. 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 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, 24a is a rack meshed 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,
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 sleeves 28.
27 is a valve body 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; , 27a, 27b, and 27c are oil passages provided on the outer peripheral surface of the valve body 27, and when the handle is in the neutral position, the high pressure oil passage 7a is connected to the oil passage 27a of the valve body 27 and the oil passage 28a of the sleeve 28. It communicates with the chamber 29 between the input shaft 21 and the torsion bar 22, and the hydraulic oil from the oil pump 1 flows through the high pressure oil path 7a → oil path 28a → oil path 2.
7a → Chamber 29 (the oil passage between oil passage 27a and chamber 29 is not shown) → Low pressure oil passage 8
Turn the handle to the right and connect the input shaft 21 so that the circulation goes from a to oil tank 4 to oil pump 1.
When rotated to the right relative to the valve body 27, the high pressure oil passage 7a is connected to the oil passage 2 of the valve body 27.
7a, 27b and the oil passage 28b of the sleeve 28 to the oil passage 9a of the power cylinder 3.
a is the oil passage 2 between the chamber 29 and the valve body 27
7c and the oil passage 10a of the power cylinder 3 via the oil passage 28c of the sleeve 28, and the hydraulic oil from the oil pump 1 is connected to the high pressure oil passage 7a.
→ Oil passage 27a → Oil passage 28b → Oil passage 9a → Oil in the left chamber of power cylinder 3 is sent, while oil in the right chamber of power cylinder 3 is sent to oil passage 10a → Oil passage 28c → Oil passage 2.
7c → Chamber 29 → Low pressure oil line 8a → Tank 4
The piston rod of the power cylinder 3 moves to the right and the steering wheel is turned to the left to rotate the input shaft 21 to the left relative to the valve body 27. Then, the high pressure oil passage 7a connects to the oil passage 27 of the valve body 27.
a and the oil passage 28c of the sleeve 28 to the oil passage 10a of the power cylinder 3, and the low pressure oil passage 8a is connected to the oil passage 10a of the power cylinder 3 via the chamber 29, the oil passage 27b of the valve body 27, and the oil passage 28b of the sleeve The hydraulic oil from the oil pump 1 is connected to the oil passage 9a from the high pressure oil passage 7a to the oil passage 27a.
→ Oil passage 28c → Oil passage 10a → The oil in the left chamber of the power cylinder 3 is sent to the right chamber, while the oil in the left chamber of the power cylinder 3 is sent 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 moves to the left, and 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 includes a sleeve 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. The spool 41 is also 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 41a 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', 40'', and notch 4 with orifice b
A notch 40e having a through hole 40e' and a through hole 40a' is provided, and a hole 40a' having a through hole 40a' is formed on the 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 the 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 a back-up spring 56 and an electromagnetic coil (solenoid) interposed between the sleeve 50
57, 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, a spring 60 interposed between the bolt 59 and the plunger 52, and a solenoid valve 13. 3D valve housing 20
As shown in FIG. 21, the sleeve 50 has an oil passage 50a communicating with the oil passage 7d on the valve housing 20 side (see FIG. 5) and a lock nut 61 on the valve housing 20 side. It has an oil passage 50b communicating with the oil passage 7e, and an orifice c is provided in the oil passage 50b. Further, the spool 51 has an oil passage 51a having an oblique groove 51a' and a through hole 51b.
2 is provided with an oil passage 52a, a through hole 52b, and an axial oil passage 52c communicating with the through hole 51b, respectively. 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. 5 is the oil passage 5 in FIG.
0a, the valve housing 20 shown in FIG.
The hydraulic oil flowing toward the solenoid valve 13 through the oil passage 7e on the side enters the oil passage 50b in FIG. 21. FIG. 21 shows the state at high speed, and in this state, only the hydraulic oil that has entered the oil passage 50b flows through the orifice c → oil passage 51a → through hole 51b → oil passage 52a → through hole 52.
b → Member 45 on the orifice d side via the oil path 52c
I will be heading to Further, when the vehicle is at high speed and then at low speed, the spool 51 is lowered to reduce the opening amount of the orifice c, while increasing the opening amount of the oil passage 50a, and when the vehicle is stopped, only the oil passage 50a is opened.
Q ₀ in Figure 1 is the flow rate on the discharge side of oil pump 1,
Q ₁ is the oil amount in the high pressure oil path 7a, Q ₂ is the flow rate in the oil path 7c,
Q ₃ indicates the flow rate of oil passage 7d (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 approximately 6:1. .Furthermore, the flow rate Q ₂ of the oil passage 7c is Q ₂ =Q ₃ +Q ₄ +Q ₅
It is. (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 in 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. I did it this way,
This is to reduce frictional resistance when inserting the sleeve 50 together with the O-ring 62 into the sleeve insertion hole of the valve housing 20, thereby making it easier to insert the sleeve 50 into the sleeve insertion hole. Also the 22nd, 2nd
The filter 70 is shown in Figures 3 and 24. This filter 70 consists of a frame 71 and a wire mesh 72,
Notch 4 provided in sleeve 40 of pressure control valve 12
0b (see FIGS. 9 and 13), that is, it is fitted into the entrance of the control system oil passage to prevent foreign matter such as dust from entering the control system oil passage. Note that foreign substances such as dust can be prevented from entering the control system oil passage by using the inlet (fourth
(see the arrow in the figure), but in that case, the entire discharge flow rate of the pump passes through, so the filter needs to be larger, and it is difficult to accommodate the filter in the space shown. The reason why the entrance of the high-pressure oil passage 7a is made larger is to make it easier to insert a drill from here and machine the orifice a and the oil passage 7b, which are branched in two directions, and at the same time to make it easier to connect the piping (not shown). This is to facilitate the joining work. In addition, other oil passages 7b (oil passages 7b, 7 on the downstream side of the change-over valve 11)
As can be seen from Figures 3, 4 and 5, holes c, 7d, 7e, etc. are formed by drilling and plugging holes in the valve housing 20 in the vertical and horizontal directions. It's summery. Second,
Z in FIGS. 3, 4, 6, and 7 is the central axis of the oil passage switching valve 2, and Z ₁ in FIGS. 2 and 5 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
83 is an error amplifier circuit, 83 is a transistor, 84 is a reset circuit that resets the timer circuit 87 when the vehicle speed is other than zero, and sets the timer circuit 87 when the vehicle speed is zero.
5 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 that 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. Engine speed setting circuit, 88
is the vehicle speed input disconnection detection circuit that is ON without a vehicle speed pulse, 89 is a transistor, 90 is a relay, 91
is a negative feedback circuit that stabilizes the current flowing through the electromagnetic coil 57 of the solenoid valve 13. According to the present control device 15, the following effects can be obtained. In other words, the engine speed is 2000 rpm at zero vehicle speed.
The above situation is normally not possible. 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
Turn ON to stop energizing the solenoid valve 13 (electromagnetic coil 57). Therefore, the steering wheel becomes difficult to operate at high speed (it has 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
(discharge pressure) P _p of the valve body 27 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 51c
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 the above stoppage, the oil pressure in oil passage 7d will
P _c starts to rise. Then, the oil pressure in the oil passage 7f also increases by the same value. This oil pressure is applied to the spool 4 of the pressure control valve ₁₂ via the main pilot oil passage 7f1.
1 (the small diameter end of the spool 41), 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 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 above 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 pressure _Pc of the oil passage 7d (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), the oil passages 7a, 7b,
Even if the oil pressure P _p 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 P _c in the oil passage 7d continues to be maintained at the low constant level. . Therefore, when increasing the relative angle to obtain a large output oil pressure P _p , the handle torque T determined by the oil pressure P _c of the reaction piston side chamber 6 and the torsion angle of the torsion bar 22 does not become large (as shown in FIG. 27). (see b). During the above-mentioned stationary cutoff, even though the oil pressure P _c 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 passage 7e is closed. Hydraulic oil does not flow. Therefore, the pressure in the pilot oil passage _7e1 becomes the same pressure as _Pc , but this pressure causes the change-over valve 11 to overcome the elasticity of the spring 33 and open the bypass oil passage 7b, as shown in FIG. It is held in the L position. 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, orifice c (sleeve 50 side oil passage 50b)
is still blocked, and due to the decrease in the opening amount of the oil passage 50a, the flow rate Q ₃ passing through the orifice d is reduced.
( _Q4 is almost zero in this state), which is lower than the flow rate from the oil passage 50a when the vehicle is stopped. Note that this decrease is the flow rate from orifice e to low pressure oil passage 8b.
Q ₅ 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 oil is stopped, the oil pressure in the oil passage 7f on the upstream side of the orifice d is stopped. lower than the time. If you start turning the steering wheel to the right (or left) at low speeds above, the oil pressure in oil passage 7d will
P _c starts 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 4
The opening degree of 0b' 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 lower than when the spool 41 is stopped, and the amount of rise of the spool 41 is correspondingly smaller (through hole 40
b') is correspondingly larger), 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 turn the steering wheel further to the right (or left),
Even if the oil pressure P _p 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 P _c of the oil passage 7d continues to be lower than when the vehicle is stopped. is also maintained at a high constant level. Therefore, by increasing the relative angle, a large output oil pressure can be obtained.
When obtaining P _p , the handle torque T becomes larger than when the vehicle is stopped, but not 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. When the steering wheel starts turning to the right (or left) at the above high speed, 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 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. Then, 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. P _c becomes 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 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 via the orifice a, and the output oil pressure is P _p 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 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. , oil passage 7 between c
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 P _p in the oil passages 7a, 7b, and 7c will further rise, but the pressure control valve 12 will open the through hole 40b'. The oil pressure P _c in the oil passage 7d is maintained at the highest constant level. Therefore, when increasing the relative angle to obtain a large output oil pressure P _p , the handle torque T becomes large (see FIG. 27B).

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 extends from the oil pump 1 to the oil passage switching valve 2 and the oil passage switching valve. 2 to the low-pressure oil passage 8a extending from the oil tank 4 to operate the power cylinder 3 in a predetermined steering direction, and at the same time, a part of the hydraulic oil flowing through the same high-pressure oil passage 7a is guided to the reaction piston 5 to direct the torsion bar 22.
In a power steering device that regulates the twisting of Road 7e, 7
an orifice b provided on one side 7e of e', a flow control valve 13 that discharges hydraulic oil from the parallel oil passage proportionally according to the vehicle speed, and a pilot installed downstream of the flow control valve 13 according to the flow rate. An orifice d that generates pressure is installed on the upstream side of the branched portions of the parallel oil passages 7e and 7e' in the branch oil passages 7b, 7c, and 7d, and is actuated by the pilot pressure to the reaction piston 5. The engine is equipped with a pressure control valve 12 that controls the oil pressure to be constant and to increase as the speed increases, and the oil pressure to the reaction piston 5 is minimized during stationary turning. 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 the steering matches the steering feel.

In addition, in this proposal, the flow control valve (solenoid valve) 13 is
1) An electromagnetic coil (solenoid) that operates the spring 60 that biases the flow control valve 13 toward the high speed position against the biasing force of the spring 60 toward the low speed position;
57 and a control device 15 that supplies a large current to the solenoid 57 at low speeds and a small current at high speeds, and the following effects can be obtained. 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 to turn on the solenoid valve 13 (electromagnetic valve 13). energization to the coil 57) is stopped. Therefore, the steering wheel becomes difficult to operate at high speed (it has a fail-safe function) and is safe.

[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, 15... ...Control device, 57...Solenoid, 6
0... Spring, a, b, c, d, e... 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 to switch between the high pressure oil passage and the low pressure oil passage extending from the oil pump to the oil passage switching valve to operate the power cylinder in a predetermined steering direction, and the same high pressure In a power steering device that controls torsion of a torsion bar by guiding a portion of hydraulic oil flowing through an oil passage to a reaction piston, a parallel oil branched from the middle of a branch oil passage extending from the high pressure oil passage to the reaction piston. an orifice installed on one side of the parallel oil passage, a flow control valve that discharges the hydraulic oil from the parallel oil passage proportionally according to the vehicle speed, and an orifice for generating pilot pressure; and an orifice disposed in the branch oil passage upstream of the branch part of the parallel oil passage and operated by the pilot pressure to keep the oil pressure to the reaction piston constant and higher at higher speeds. a pressure control valve that controls the flow rate control valve to move toward the low speed position against the biasing force of a spring that biases the flow rate control valve toward the high speed position; A power steering device characterized by comprising a solenoid that is operated to operate the solenoid, and a control device that supplies a large current to the solenoid at low speeds and a small current at high speeds.