JPH0686223B2 - Power steering device - Google Patents

Description

The present invention relates to an input shaft and an output shaft, which are coaxially and rotatably supported in a housing and elastically coupled to each other via a torsion bar, and a steering wheel steering wheel. An oil passage switching valve that controls the supply and discharge of hydraulic oil to and from a power cylinder that exerts an assist force on the output shaft according to the relative rotation of the input shaft and the output shaft due to operation, and the oil passage is switched from an oil pump. The high pressure oil passage extending to the valve, the low pressure oil passage extending from the oil passage switching valve to the oil tank, and a part of the hydraulic oil flowing through the high pressure oil passage is guided to the reaction force piston to generate the same pressure due to the hydraulic pressure of the hydraulic oil. In a power steering device including a reaction force mechanism in which a reaction force piston is driven at least in a radial direction of an input shaft or an output shaft to restrict torsion of the torsion bar, a power steering device extends from the high pressure oil passage to the reaction force piston. The parallel oil passage diverged from the middle of the parallel oil passage, the second orifice provided in one of the parallel oil passages, and the discharge amount of the hydraulic oil from both of the parallel oil passages are made variable according to the vehicle speed. A flow rate control valve, a first orifice provided in an oil passage extending to the oil tank downstream of the flow rate control valve to generate a main pilot pressure according to a flow rate, and the second orifice operated by the main pilot pressure. And a pressure control valve for controlling the hydraulic pressure to the reaction force piston upstream of the orifice so that it is constant at each vehicle speed and becomes higher at higher vehicle speeds.

The present invention also provides an input shaft and an output shaft, which are coaxially rotatably supported in a housing and elastically coupled to each other via a torsion bar so that they can rotate relative to each other, and the input shaft associated with a steering handle steering operation. And an oil passage switching valve that controls the supply and discharge of hydraulic oil to and from a power cylinder that applies an assisting force to the output shaft according to the relative rotation between the output shaft and the output shaft, and high-pressure oil that extends from the oil pump to the oil passage switching valve. Passage, a low-pressure oil passage extending from the oil passage switching valve to the oil tank, and part of the hydraulic oil flowing in the high-pressure oil passage is guided to the reaction force piston, and at least the reaction force piston is input by the oil pressure of the operation oil. In a power steering device including a reaction force mechanism that drives in a radial direction of a shaft or an output shaft to regulate the torsion of the torsion bar, in an oil passage extending from the high pressure oil passage to the reaction force piston Parallel oil passage, a second orifice provided in one of the parallel oil passages, a flow rate control valve for varying the discharge amount of hydraulic oil from both of the parallel oil passages according to the vehicle speed, and the same flow rate. A first orifice provided in an oil passage extending to the oil tank downstream of the control valve to generate a main pilot pressure according to a flow rate, and the reaction piston upstream of the second orifice operated by the main pilot pressure. Is provided between the pressure control valve that controls the oil pressure of the oil passage to the vehicle to be constant at each vehicle speed and becomes higher at higher speeds, and the oil passage extending to the reaction force piston and the high pressure oil passage, and does not steer at high speed. Only in the vicinity of the neutral position, the pilot pressure generated between the second orifice provided in one of the parallel oil passages and the flow control valve operates in the closing direction to set the oil pressure of the oil passage to the reaction piston to a predetermined value. Price increase And it includes a change-over valve to.

Further, according to the present invention, an input shaft and an output shaft, which are coaxially rotatably supported in a housing and elastically connected to each other via a torsion bar so as to be rotatable relative to each other, and the input according to a steering operation of a steering wheel. Oil passage switching valve that controls the supply and discharge of hydraulic oil to and from a power cylinder that applies an assist force to the output shaft in accordance with the relative rotation between the output shaft and the output shaft, and a high pressure that extends from the oil pump to the oil passage switching valve. Part of the hydraulic oil flowing through the oil passage, the low-pressure oil passage extending from the oil passage switching valve to the oil tank, and the high-pressure oil passage is guided to the reaction force piston, and the reaction force piston causes at least the reaction force piston to move at least. In a power steering device including a reaction force mechanism that drives in a radial direction of an input shaft or an output shaft to control the torsion of the torsion bar, in an oil passage extending from the high pressure oil passage to the reaction force piston Parallel oil passage, a second orifice provided on one of the parallel oil passages, a flow control valve for varying the discharge amount of hydraulic oil from both of the parallel oil passages according to the vehicle speed, and the same flow rate. A first orifice provided in an oil passage extending to the oil tank downstream of the control valve to generate a main pilot pressure according to a flow rate, and the reaction piston upstream of the second orifice operated by the main pilot pressure. A pressure control valve for controlling the oil pressure to the vehicle so that it is constant at each vehicle speed and becomes higher at higher speeds; an oil passage extending downstream of the pressure control valve; and an oil passage extending to the oil tank downstream of the flow control valve. Corresponding to an increase in the flow rate from the downstream side of the pressure control valve to the low pressure oil passage, which is provided in the middle of the oil passage connecting to the low pressure oil passage, from the first orifice on the downstream side of the flow control valve to the low pressure oil passage. Decrease And comprising a third orifice to adjust to increase if.

The object of the present invention is to keep the hydraulic pressure to the reaction force piston low and constant at the time of stopping and low speed to give a light steering feeling,
On the contrary, at high speeds, the hydraulic pressure can be kept high and constant to provide an appropriate response. Further, the discharge pressure from the oil pump can be positively increased even in the vicinity of the neutral position of the steering rig handle that is not steered at high speed, and a sense of rigidity can be obtained. Further, another object of the present invention is to provide a power steering device that can make the flow of hydraulic oil from the high-pressure oil passage to the oil passage switching valve constant and stabilize the control characteristics of the oil passage switching valve.

Next, the power steering device of the present invention will be described with reference to FIGS.
This will be described with reference to an embodiment shown in the figure. First, the outline will be described with reference to FIG. 1. (1) is an oil pump driven by an engine (not shown).
Has a constant flow rate (about 7 / min) and a variable discharge pressure (5k
It is an oil pump of g / cm ^{2 to} 70 kg / cm ² . Also (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 force pistons, and (6) is each reaction force piston (5 )
A chamber (7a) formed behind the high pressure oil passage extending from the oil pump (1) to the oil passage switching valve (2),
(8a) extends from the oil passage switching valve (2) to the oil tank (4), and low pressure oil passages (9a) and (10a) extends from the oil passage switching valve (2) to the power cylinder (3). Oil passage, (a) is a main orifice provided in the middle of the high pressure oil passage (7a), and (7b) is a bypass connected to the high pressure oil passage (7a) upstream and downstream of the main orifice (a). Oilways, (11)
Is a changeover valve (COV), (12) that constitutes hydraulic pressure increasing means interposed in the middle of the bypass oil passage (7a)
Is a pressure control valve connected to the oil passage (7b) upstream of the changeover valve (11) via the oil passage (7c),
(13) is a flow control valve, (7d) is an oil passage extending from the pressure control valve (12), and a pair of parallel oil passages (7e) (7e ') diverged from the oil passage (7d) are the above. Solenoid valve (1
It extends to 3). Further, (7d ₁ ) is a sub pilot oil passage extending from the middle of the oil passage (7d) to the pressure control valve (12), and (7d ₂ ) is a portion of the oil passage (7d) from the reaction piston (5). ), An oil passage extending to the chamber (6) behind
(7d ₃ ) is an oil passage extending from the middle of the oil passage (7d) to the low pressure oil passage (8b), and (b) and (c) are second and fourth oil passages provided in the middle of the oil passage (7e), respectively. Is the COV pilot oil passage (7e ₁ ) extending from the oil passage (7e) between the orifices (b) and (c) to the changeover valve (COV) (11), and (e) is the above. A third orifice provided in the middle of the oil passage (7d ₃ ), an oil passage (7f) extending from the solenoid valve (13) to the low pressure oil passage (8b), and (d) an oil passage (7).
The first orifice, (7f ₁ ), provided in the middle of f), is the first
Main pilot oil passage extending from the oil passage (7f) upstream of the orifice (d) to the pressure control valve (12), (14) a vehicle speed sensor, (15) a control device, and (16) an ignition. Switch, (17) is ignition coil, (18a) (1
8b) is a wiring extending from the control device (15) to the electromagnetic coil of the solenoid valve (13), the vehicle speed sensor (14) detects the vehicle speed, and a pulse signal (responding to the vehicle speed) obtained as a result is detected. So that the pulse signal) is sent to the control device (15), and the control device (15) responds to the current corresponding to the pulse signal (current zero at a predetermined high speed (i = 0) to current when the vehicle is stopped). (Current corresponding to vehicle speed up to maximum (i = 1))
Is sent to the electromagnetic coil (57) of the solenoid valve (13) to hold the plunger (52) and the spool (51) of the solenoid valve (13) at a predetermined position according to the current value.

Next, the oil passage switching valve (2), the changeover valve (11), the pressure control valve (12), and the solenoid valve (1
3) and will be specifically described with reference to FIGS. 2 to 21. 2 to 7 shows a valve housing (20), and the valves (2), (11), (12) and (13) are incorporated in the valve housing (20).

First, the oil passage switching valve (2) will be described in detail with reference to FIG. 2. (21) is an input shaft operated by a steering handle (not shown), and (23) in FIGS. 2 and 3 are upper and lower bearings. A cylinder block (22) constituting an output shaft rotatably supported in the valve housing (20) by means of a torsion bar inserted in the input shaft (21), and the upper portion of the torsion bar (22) is the input. The upper part of the shaft (21) is fixed to the cylinder block (23), and the lower part is fixed to the cylinder block (23). The relative rotation angle difference between the input shaft (21) and the cylinder block (23) due to the torsion of the torsion bar (22) is shown. It is configured to allow. Also, (21a) is the input shaft (2
The cylinder block (23) is provided with a plurality of vertical grooves on the lower outer peripheral surface of 1) so as to face the vertical grooves (21a), and the reaction pistons ( 5) is inserted and the projection provided at the tip of each reaction force piston (5) is engaged with each vertical groove (21a). The chamber (6) behind each reaction piston (5) is formed between the cylinder block (23) and the valve housing (20) and communicates with the annular groove (6 '). Further, (23a) is a pinion integrated with the cylinder block (23), (24a) is a rack meshing 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 directly above the cylinder block (23). Of the oil passage switching valve (2) fixed in the valve housing (20) of (2), oil passages (28a) (28b) (28c) provided on the outer peripheral surface of the sleeve (28), and (27) of the same sleeve. A valve body (23b) fitted between (28) and the input shaft (21) connects a lower end of the valve body (27) with an upper end of the cylinder block (23),
(27a) (27b) (27c) are oil passages provided on the outer peripheral surface of the valve body (27). In the above configuration, when the steering handle is in the neutral position, the high pressure oil passage (7
a) is the valve body (27) oil passage (27a) and sleeve (2)
The hydraulic oil from the oil pump (1) communicates with the chamber (29) between the input shaft (21) and the torsion bar (22) via the oil passage (28a) in (8). ) → Oil passage (28a) → Oil passage (27a) → Chamber (29) (The oil passage between the oil passage (27a) and the chamber (29) is not shown)
→ The low pressure oil passage (8a) → the oil tank (4) → the oil pump (1) circulates. When the steering handle is turned to the right and the input shaft (21) is rotated to the right relative to the valve body (27), the high pressure oil passage (7
a) is through the oil passages (27a) (27b) of the valve body (27) 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 power cylinder (3) through the oil passage (27c) of the chamber (29), the valve body (27) and the oil passage (28c) of the sleeve (28).
Hydraulic fluid from the oil pump (1) communicates with the respective oil chambers (10a) of the high pressure oil passage (7a) → oil passage (27a) →
Oil passage (28b) → oil passage (9a) → oil in the right chamber of the power cylinder (3) is sent to the left chamber of the power cylinder (3) while oil passage (10a) → oil passage (28c) → oil passage (27c) → Chamber (29) → Low pressure oil passage (8a) → Return to tank (4), piston rod of power cylinder (3) moves to the right, and steering to the right is performed. When the steering handle is turned to the left and the input shaft (21) is rotated to the left relative to the valve body (27), the high pressure oil passage (7a) causes the oil passage (27a) of the valve body (27) and the sleeve ( 28) oil passage (28
c) to the oil passage (10a) of the power cylinder (3),
Low pressure oil passage (8a) Chamber (29) and valve body (27)
The hydraulic oil from the oil pump (1) communicates with the oil passage (9a) of the power cylinder (3) through the oil passage (27b) and the oil passage (28b) of the sleeve (28), respectively. Oil passage (7
a) → oil passage (27a) → oil passage (28a) → oil passage (10a) → sent to the right chamber of the power cylinder (3), while the oil in the left chamber of the power cylinder (3) flows to the oil passage (9a) → oil passage (28b) → oil passage (2
7b) → chamber (29) → low pressure oil passage (8a) → returned to the tank (4), the piston rod of the power cylinder (3) moves to the left, and steering to the left is performed. .

Next, the changeover valve (11) that constitutes the hydraulic pressure increasing means will be described in detail. The changeover valve (11) is, as shown in FIGS. 4 and 7, an orifice (a). It is installed in the middle of the bypass oil passage (7b). The changeover valve (11) has an annular groove (30a) (this annular groove (30a) is part of the oil passage (7b)).
Spool (30) (note that this spool (30) shows the position when not steered at high speed), cap (31) and these spools (30) and cap (3
1) has a spring (33) and an O-ring (34) interposed, and when the oil pressure in the pilot oil passage (7e ₁ ) (see FIG. ₁ ) increases, the spool (30) causes the spring (33) ) To move forward,
When the oil pressure in the pilot oil passage (7e ₁ ) decreases so that the bypass oil passage (7b) is opened, the spool (30) causes the spring (3
It retreats by 3) and closes the bypass oil passage (7b).

Next, specifically explaining the pressure control valve (12),
The pressure control valve (12) includes a sleeve (40), a spool (41), a cap (42), a stopper (43), and these spools (41), as is clear from FIGS. 5, 6, 7, and 8. And a spring (44) interposed between the stopper (43) and a first orifice (d) fixed in the spool (41). As shown in FIGS. 9, 10, and 11, the spool (41) is provided with three annular grooves (41a) (41b) (41c), and the annular groove (41a) is provided in the bypass oil passage (7b). ) Changeover valve (11) upstream from the oil passage (7
Facing c). Further, (41d) is a chamber that extends upward from the first orifice (d) in the spool (41), and (41e) is an oil passage that connects the chamber (41d) and the annular groove (41c). These (41d) (41e) (4
1c) is a part of the low-pressure oil passage (8b), and has the same annular groove (41c)
Is a valve housing (20) side that extends obliquely downward from the low pressure oil passage (8b) formed immediately above the valve body (27) of the oil passage switching valve (2) shown in FIG. 2 as shown in FIG. It faces the low pressure oil passage (8b).

The annular groove (41a) communicates with the chamber (41d) via a third orifice (e). Further, as shown in FIGS. 11 to 17, the sleeve (40) has a notch portion (40d) having a through hole (40d ′) and a through hole (40d ′) with different phases in the circumferential direction of the outer peripheral surface. Hole (40c ') (40
notch (40c) having a c ″), a notch (40d) having a second orifice (b), and a notch (40) having a through hole (40e ′).
e) is provided.

In the above grooves and the like, the notch (40a) having the through hole (40a ') has an annular groove (41c) of the spool (41) and a valve housing (2
The notch (40b) connecting the low pressure oil passage (8b) on the 0) side and having the through hole (40b ') has the annular groove (41a) of the spool (41) and the oil passage (7c on the valve housing (20) side. ) And the notch (40c) with the through holes (40c ′) (40c ″) is connected to the spool (4
The notch (40d) connecting the annular grooves (41a) and (41b) of 1) and having the second orifice (b) has an oil groove (41b) on the spool (41) and an oil passage (20) on the valve housing (20) side. 7e) and a notch (40e) having a through hole (40e ′) is formed in the annular groove (41b) of the spool (41) and the oil passage (7d on the valve housing (20) side shown in FIGS. ) Is connected to. And the first
Oil from the orifice (d) to the chamber (41d) of the spool (41) is oil passage (41e) → annular groove (41c) → through hole (40a ') → notch (40a) → valve housing (20)
Return to the oil tank (4) via the low pressure oil passage (8b).
Further, the hydraulic oil that has entered the cutout portion (40b) from the bypass oil passage (7b) through the oil passage (7c) passes through the through hole (40b ') → the annular groove (41
a) → notch (40c) → through hole (40c ″) → annular groove (41b)
→ through hole (40e ′) → notch (40e) → configured to go toward the solenoid valve (13) through the oil passage (7d) on the valve housing (20) side, and from the notch (40c) It is configured to go toward the reaction force piston (5) via the oil passage (7d ₂ ). Further, a part of the hydraulic oil flowing in the annular groove (41b) is transferred from the orifice (b) to the notch (40
d) → acts as pilot pressure behind the spool (30) of the changeover valve (11) via the oil passage (7e) on the valve housing (20) side (see (7e ₁ ) in Fig. 5) , And further toward the solenoid valve (13) via the oil passage (30b) provided at the rear end of the spool (30) (see FIG. 7) → the oil passage (7e) on the valve housing (20) side. It has become.

Next, the solenoid valve (13) will be described in detail. As shown in FIGS. 5, 8, and 21, the solenoid valve (13) has its axes aligned directly below the pressure control valve (12). It is arranged to do. The solenoid valve (13) includes a sleeve (50), a spool (51), a non-magnetic material plunger (52), a magnetic material member (53) integrated with the plunger (52), and the spool (51). A lock nut (54) tightened and fixed to the plunger (52) and a seat plate (5) abutting against the sleeve (40) of the pressure control valve (12).
5) a backup spring (56) and an electromagnetic coil (57) interposed between the seat plate (55) and the sleeve (40).
Between the nut (58) fixed to the casing of the same electromagnetic coil (57) and the plunger pressing force adjusting bolt (59) screwed to the nut (58), the bolt (59) and the plunger (52). It has a spring (60) and a lock nut (61) for fixing the assembly of the solenoid valve (13) to the valve housing (20) by fastening. The sleeve (50) is attached to the valve housing (2) as shown in Fig. 21.
An annular oil passage (50a) communicating with the oil passage (7e ′) on the 0) side (see FIG. 5) and an oil passage (7e) on the valve housing (20) side
And an annular oil passage (50b) communicating with the oil passage (50b)
There is an orifice (c). Further, the spool (51) has an oblique groove (51a ') formed only in a part in the circumferential direction and has an annular oil passage (51a) and a through hole (51b) formed all around. The plunger (52) has an oil passage (52a) communicating with the through hole (51b), a through hole (52b), and an oil passage (52c) in the axial direction.

As already mentioned, the valve housing (20) shown in FIG.
The hydraulic oil flowing from the side oil passage (7d) to the solenoid valve (13) via (7e ') enters the oil passage (50a) in FIG.
The hydraulic oil flowing through the oil passage (7e) on the valve housing (20) side shown in FIG. 5 toward the solenoid valve (13) enters the oil passage (50b) shown in FIG. FIG. 21 shows the state at high speed. In this state, only the hydraulic oil entering the oil passage (50b) is in the fourth orifice (c) → oil passage (51a) → through hole (51b).
→ Oil passage (52a) → Through hole (52b) → Oil passage (52c) to the member (45) on the orifice (d) side. Also, at high speed → low speed, the spool (51) descends and the opening amount of the orifice (c) decreases, while the opening amount of the oil passage (50a) increases, so that the stopped vehicle is equipped with the oil passage (50a). ) Only open.

In Fig. 1, Q ₀ is the flow rate on the discharge side of the oil pump (1), Q ₁ is the amount of oil in the high pressure oil passage (7a), Q ₂ is the flow rate in the oil passage (7c), and Q ₃ is the oil passage (7d). (Oil passage (50a) flow rate, Q ₄ is the flow rate on the downstream side of orifice (c), Q ₅ is the flow rate on the downstream side of orifice (e), and Q ₁ : Q ₂ is about 6: 1. . Also, the flow rate Q of the oil passage (7c)
₂ is Q ₂ = Q ₃ + Q ₄ + Q ₅ (see Fig. 30).

The diameter of the sleeve (50) of the solenoid valve (13) is
As shown in FIG. 21, the upper part, the middle part, and the lower part are different, and the upper part is smaller, and there is a difference (D ₁ ) (D ₂ ) between them. On the other hand, the sleeve fitting hole on the side of the valve housing (20) is also formed so as to match it. This is because when the sleeve (50) is inserted into the sleeve (50) together with the O-ring (62), the frictional resistance is reduced to facilitate the insertion of the sleeve (50) into the sleeve fitting hole.
This is to prevent each O-ring (62) from protruding and being caught between the sleeve (50) and the valve housing (20) when the sleeve (50) is inserted. Also the 22,23,
Figure 24 shows the filter (70). This filter (7
0) consists of a frame (71) and a wire mesh (72), and is a notch (40b) provided in the sleeve (40) of the pressure control valve (12).
(See FIGS. 9 and 13) That is, it is inserted into the inlet of the control system oil passage to prevent foreign matters such as dust from entering the control system oil passage. It should be noted that foreign matter such as dust is prevented from entering the control system oil passage by providing this kind of filter at the inlet of the high pressure oil passage (7a) (see the arrow in Fig. 4) provided in the valve casing (20). However, in this case, since the entire discharge flow rate of the pump passes, it is necessary to use a large filter, and the spacer shown makes it difficult to store the filter. Note that the inlet of the high-pressure oil passage (7a) has a large diameter because a drill is inserted from here to facilitate the machining of the orifice (a) and the oil passage (7b) branched in two directions, and at the same time the piping This is for facilitating the connection work with (not shown). In addition, other oil passages (7b) (oil passage (7b) downstream of the changeover valve (11)) 7
c) (7d), (7e), etc. are also formed by making holes in the valve housing (20) from the vertical and horizontal directions and plugging them, as is clear from Figs. However, processing of oil passages is easy. Incidentally, Z in FIGS. 2, 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).

An example of the control device (15) is shown in FIG. (8
0) 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, (83) is a transistor, and (84) is a timer circuit when the vehicle speed is not zero. (87) Reset the timer circuit at zero vehicle speed (87)
Reset circuit for resetting the voltage, (85) pulse-voltage conversion circuit for sending a voltage proportional to the engine speed, (86)
When the engine speed is 2000 rpm or more, the timer circuit (8
Engine speed setting circuit that turns the timer circuit (87) to OFF when the engine speed is 2000 rpm or less, and the vehicle speed input disconnection detection circuit that the (88) is ON without the vehicle speed pulse, (89) Is a transistor, (90) is a relay, (9
1) is a negative feedback circuit that stabilizes the current flowing through the electromagnetic coil (57) of the solenoid valve (13). In general, it is usually impossible for the vehicle speed to be zero and the engine speed to be 2000 rpm or more. Therefore, if this state continues for 5 to 10 seconds or longer, it is judged that some kind of failure (for example, failure of the vehicle speed pulse system) has occurred, the relay (90) is turned on, and the solenoid valve (13) (electromagnetic coil Stop energizing (57)).

Therefore, according to this control circuit, the solenoid valve (13) is de-energized at the time of failure, and the steering wheel operation becomes heavy at a high speed (having a fail-safe function), which is safe.

Next, the operation of the power steering device will be described. The output hydraulic pressure (discharging pressure of the oil pump (1)) P _P of the oil passage switching valve (2) is set to the relative angle of the input shaft (21) with respect to the valve body (27) by turning the steering handle from the neutral position to the right or left. When becomes larger, it rises by drawing a quadratic curve as shown in Fig. 26. Discharge pressure P _{P of} this oil pump (1)
Is influenced by the oil passages (7a), (7b) and (7c) and the pressure control valve (12) and the oil passage (7d) (orifice (b) (e) and solenoid valve (13) on the downstream side. Oil passage (7d) upstream from the force piston side chamber (6)
The oil pressure P _C of the oil passage (7d) appears with the same tendency.
Will rise as well. The pressure control valve (12) controls the discharge pressure P _P of the oil pump (1) by the sub pilot oil passage (7d ₁ ) on the downstream side of the pressure control valve (12) to limit the control oil pressure P _C to a predetermined maximum oil pressure or less. In addition, the maximum hydraulic pressure of the control hydraulic pressure P _C is controlled as shown in FIG. 29 by the main pilot hydraulic pressure of the oil passage (7f ₁ ) downstream of the flow control valve (13). When the vehicle is stopped, the control device (15) receives a pulse signal from the vehicle speed sensor (14) and sends a current of i = 1A (see Fig. 29) to the solenoid valve (13) to cause the plunger ( 52) and the spool (51) are lowered to the lower limit position (moved to the L position in FIG. 1) and the oil passage (50
Oil only (a) on the spool (51) side (51a) (51b) (51
via the oil passage (7) upstream of the first orifice (d)
The hydraulic pressure of the oil passage (7f) is set to the same value as the hydraulic pressure P _C of the oil passage (7d) by communicating with the oil passage (7f). When the steering handle is turned to the right (or left) when the vehicle is stopped, the hydraulic pressure P _C of the oil passage (7d) starts to rise. Then, the oil pressure in the oil passage (7f) also rises with the same tendency. This oil pressure is transferred to the spool (41) of the pressure control valve (12) via the main pilot oil passage (7f ₁ ).
It is directly transmitted to (the small diameter side of the spool (41)) and the spool (41) is pushed in the direction of the arrow in FIG. At the same time, the hydraulic pressure P _C of 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), the spool (41) gradually rises against the spring (44), and the opening degree of the through hole (40b ') gradually decreases. Yuki, when the hydraulic pressure pushing in the direction of the arrow and the spring force balance,
The spool (41) stops. In this state, the oil passage (7d)
The maximum value of the hydraulic pressure P _C of (the reaction force piston side chamber (6)) becomes the lowest. This state is the same from then on, when the steering wheel is further turned to the right (or left) and the discharge hydraulic pressure P _{P of} the oil passages (7a) (7b) (7c) further rises,
The pressure control valve (12) is moved in the direction to further close the opening of the through hole (40b ') due to the difference in pressure receiving area of the discharge hydraulic pressure P _P acting on the annular groove (41b), and the hydraulic pressure of the oil passage (7d) is moved. P _C
Is maintained at the above low constant level. Therefore, when the relative angle is increased to obtain a large discharge hydraulic pressure P _P , the handle torque T determined by the hydraulic pressure P _C of the reaction force piston side chamber (6) and the twist angle of the torsion bar (22) does not increase ( (See (a) in Fig. 27). At the above stationary operation, the spool (51) (see Fig. 21) is descending even though the oil pressure P _C of the oil passage (7d) is low as described above. Therefore, the fourth orifice (c) is closed,
No hydraulic oil flows into the oil passage (7e). Therefore, the pressure in the COV pilot oil passage (7e ₁ ) becomes the same as Pc, but this pressure causes the changeover valve (11) to spring (33).
The bypass oil passage (7b) is opened by overcoming the resilience of (1) and held at the L position in FIG. Note that FIG. 1 shows the H position.

In addition, if the car enters a low speed running state, the control device (15)
Receives a pulse signal from the vehicle speed sensor (14), sends a current corresponding to the vehicle speed at that time, for example, a current of i = 0.8 to the solenoid valve (13), and lowers the plunger (52) and spool (51) to the lower limit. Raise from the position by the distance corresponding to the above current value (moved to the right in FIG. 1),
The opening amount of the oil passage (50a) on the sleeve (50) side shown in the figure is reduced. At this time, the fourth orifice (c) (sleeve (50) side oil passage (50b)) is still closed, and the first orifice (d) is changed due to the decrease in the opening amount of the oil passage (50a). The passing flow rate Q ₃ (Q ₄ is almost zero in this state) is
It is smaller than the flow rate from the oil passage (50a) when the vehicle is stopped.
The reduced amount is absorbed by the increase in the flow rate Q ₅ from the third orifice (e) to the low pressure oil passage (8b). As described above, the flow rate Q ₃ (Q ₄ ≈ 0) exiting the solenoid valve (13) is smaller than the flow rate Q ₃ from the oil passage (50a) when the vehicle is stopped, so that the first upstream of the orifice (d) Oil pressure on the side oil passage (7f) becomes lower than when the vehicle was stopped.

At the above low speed, turn the steering handle to the right (or left)
When it starts to turn off, the oil pressure P _C of the oil passage (7d) starts to rise.
Then, the main pilot oil pressure in the oil passage (7f) also rises. This oil pressure is transferred to the spool (41) (spool (41) of the pressure control valve (12) via the main pilot oil passage (7f ₁ ).
(Small diameter end) of 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. Meanwhile, springs (44)
The side communicates with the low-pressure oil passage (8b), the spool (41) gradually rises against the spring (44), and the opening of the through hole (40b ') gradually decreases. When the pushing hydraulic pressure and the spring force balance, the spool (41) stops.
However, the hydraulic pressure pushing the small diameter end of the spool (41) is lower than when the vehicle is stopped, and the amount of rise of the spool (41) is smaller by that much (the amount of opening of the through hole (40b ') is larger by that much). ), Oil passage (7d) (reaction force piston side chamber (6))
The oil pressure P _C becomes higher than that when the _vehicle is stopped. This state is the same from then on, turning the steering handle further to the right (or left), the oil pressure P _{P in} the oil passages (7a) (7b) (7c) further rises, and the oil pressure in the annular groove (41b) increases. When the pressure is increasing, the pressure control valve (12) further moves the spool (41) to limit the opening of the through hole (40b '), and the hydraulic pressure P _C of the oil passage (7d) continues to be higher than when the vehicle was stopped. Is also maintained at a high constant level.

Therefore, when the relative angle is increased to obtain a large discharge hydraulic pressure P _P , the steering wheel torque T becomes larger than that when the vehicle is stopped, but it does not become large as in the high speed described later.

When the vehicle enters a high speed state of a predetermined speed, the control device (15) receives a pulse signal from the vehicle speed sensor (14) and applies a current of i = 0 (see FIG. 29) to the solenoid valve (1).
3), the flanger (52) and the spool (51) are raised by the spring (60) to the upper limit position (moved to the H position shown in FIG. 1), and the fourth orifice (c) shown in FIG. ) Only spool (51) side oil passage (51a) (51b)
It communicates with the oil passage (7f) on the upstream side of the first orifice (d) via (52b). At this time, the fourth orifice (c) is fully opened, and the flow rate of the fourth orifice (c) is increased.
Q ₄ are increased, but only a slight increase compared to the time of the low speed. On the other hand, the flow rate Q ₃ of the oil passage (50a) becomes almost zero, so
This system has the lowest flow rate. This reduction is
Flow rate Q ₅ from the third orifice (e) to the low pressure oil passage (8b)
Is further increased and absorbed (see FIG. 31). As described above, the flow rate leaving the solenoid valve (13) is reduced most, so that the main pilot oil pressure in the oil passage (7f) on the upstream side of the first orifice (d) becomes the lowest. This hydraulic pressure is applied to the oil passage (7f
_Since it is supplied to the pressure control valve (12) via ₁ ),
The maximum pressure of the hydraulic pressure P _C , which is limited by the pressure control valve (12), becomes maximum (see Fig. 29).

At the above high speeds, turn the steering wheel to the right (or left)
When it starts to turn off, the oil pressure P _C of the oil passage (7d) starts to rise.
Then, the oil pressure in the oil passage (7f) also rises. However, since the oil passage (50a) is blocked, the amount of rise is extremely small. This hydraulic pressure is transmitted through the main pilot (7f ₁ ) to the spool (41) (spool (41) of the pressure control valve (12).
It is directly transmitted to the small diameter end) and the spool (41) is
10 Pushed in the direction of the arrow in the figure. 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), the spool (41) gradually rises (moves in the L direction in FIG. 1) against the spring (44), and the through hole ( When the opening of 40b ') becomes gradually smaller and the hydraulic pressure and spring force pushed in the direction of the above arrow balance,
The spool (41) stops. However, the hydraulic pressure that pushes the small diameter end of the spool (41) is the lowest, the amount of rise of the spool (41) is very small (the opening of the through hole (40b) is large), and the oil passage (7d) (reaction force) The maximum pressure of the hydraulic pressure P _C of the piston side chamber (6) is the highest. On the other hand, since the fourth orifice (c) is opened to the oil passage (51a), particularly when the steering handle is near the neutral position and the discharge pressure P _P itself is low, the second and fourth orifices ( The COV pilot pressure in the oil passage (7e) between b) and c) decreases and this is the COV
It is transmitted to the spool (30) of the changeover valve (11) via the pilot oil passage (7e ₁ ), the spool (30) descends (H position is selected in Fig. 1), and the bypass oil passage (7b) is closed, the hydraulic oil from the oil pump (1) is sent to the oil passage switching valve (2) via the main orifice (a), and the discharge pressure P _P rises by the set pressure. This means that the discharge pressure P _{P of} the oil passages (7a) (7b) (7c) rises more than when the _vehicle is stopped or at low speed even when steering is not performed at high speed (handle neutral position) (Fig. 27). P reference _P1), the hydraulic pressure is transmitted to the pressure control valve (12) and the oil passage (7a) (through 7d ₂₎ reaction piston side Chiyanba (6), anti force sensation of the micro steering at the time of high speed (Response) is improved. Continue turning the steering wheel further to the right (or left),
The discharge pressure P _{P of the} oil passages (7a) (7b) (7c) further increases,
As described above, the oil pressure P _C of the oil passage (7d) further rises, and the oil pressure of the oil passage (7e) between the orifices (b) and (c) rises above the set value, and the pilot oil passage ( When the force acting on the spool (30) via 7e ₁ ) becomes larger than the force of the spring (33), the spool (30) of the changeover valve (11) rises (the L position in FIG. Selected),
The bypass oil passage (7b) is opened. Even in this state, if the steering wheel is kept turned to the right (or left), the oil pressure P _{P in} the oil passages (7a) (7b) (7c) will rise further, but the pressure control valve (12) Controls the opening of the through hole (40b ') to keep the hydraulic pressure P _C of the oil passage (7d) at the highest constant level. Therefore, the steering wheel torque T for increasing the relative angle and obtaining the large output hydraulic pressure P _P increases (see (b) in FIG. 27).

The present invention provides a high pressure oil passage extending from the oil pump to the oil passage switching valve by transmitting the movement of the steering wheel to the oil passage switching valve via the torsion bar, and a low pressure oil passage extending from the oil passage switching valve to the oil tank. The steering force of the steering wheel is controlled by switching the power cylinder to operate in a predetermined steering direction and guiding a part of the hydraulic oil flowing through the high pressure oil passage to the reaction force piston to control the torsion of the torsion bar. is there.

Then, a second orifice is provided on one of the parallel oil passages extending from the middle of the oil passage extending from the high pressure oil passage to the reaction piston.
Moreover, by providing a flow rate control valve that makes the discharge amount of hydraulic oil from both parallel oil passages variable according to the vehicle speed, the main pilot pressure generated downstream of the flow rate control valve is changed according to the vehicle speed, Moreover, since the pressure control valve is operated by the main pilot pressure, it is possible to control the hydraulic pressure to the reaction force piston so that it is constant at each vehicle speed and becomes higher at higher vehicle speeds. Therefore, when the vehicle is stopped or at a low speed, the hydraulic pressure to the reaction force piston can be kept low and constant to give a light steering feeling, and conversely, when the vehicle is high speed, the hydraulic pressure can be kept constant to a high level to provide an appropriate response.

Further, between the second orifice and the flow control valve, which are provided between the oil passage extending to the reaction force piston and the high-pressure oil passage, and which are provided on one side of the parallel oil passage only near the neutral position where steering is not performed at high speed. A changeover valve that operates in the circumferential direction by the pilot pressure generated at the wheel to raise the oil pressure in the oil passage to the reaction piston by a specified value is provided so that the oil pump can be operated even near the neutral position of the steering wheel that does not steer at high speed. The discharge pressure from can be positively increased, and a feeling of rigidity can be obtained.

Further, the flow rate of the flow from the downstream side of the pressure control valve to the low pressure oil path is controlled by being provided in the middle of the oil path connecting the oil path extending to the downstream side of the pressure control valve and the oil path extending to the oil tank on the downstream side of the flow rate control valve. By providing the third orifice which adjusts so as to increase if it decreases in response to the increase or decrease from the first orifice on the downstream side of the valve to the low pressure oil passage,
The total flow rate from the oil passage to the reaction force piston to the low pressure oil passage can be made almost constant, that is, the working flow rate from the high pressure oil passage to the reaction force piston becomes substantially constant, so that the high pressure oil passage to the oil passage switching valve This has the effect of making the flow of hydraulic oil constant and stabilizing the control characteristics of the oil passage switching valve.

[Brief description of drawings]

FIG. 1 is a hydraulic circuit diagram showing an embodiment of a power steering device according to the present invention, FIG. 2 is a vertical sectional side view of an oil passage switching valve, FIG. 3 is a bottom transverse plan view thereof, and FIG. FIG. 5 is a vertical cross-sectional side view of the changeover valve, pressure control valve and solenoid valve, and FIG. 6 is a vertical cross-sectional side view of the oil passage switching valve and pressure control valve. Is a vertical cross-sectional side view of the oil passage switching valve and the changeover valve, and FIG. 8 (I) is an enlarged vertical cross-sectional side view of the changeover valve, the pressure control valve, and the solenoid valve. ) Is an end view of the solenoid valve, FIG. 9 is an enlarged longitudinal side view of the pressure control valve, FIG. 10 is an enlarged longitudinal side view of the same, FIG. 11 is an enlarged plan view of the sleeve of the pressure control valve, and FIG.
Fig. 1 is a side view of the enlarged longitudinal section, Fig. 13 is another side view of the enlarged longitudinal section, Fig. 14 is a cross-sectional plan view taken along the line XIV-XIV in Fig. 12, and Fig. 15 is an arrow in the direction of Fig. 13. A cross-sectional plan view along the line XV-XV,
FIG. 16 is a cross-sectional plan view taken along the line XVI-XVI in FIG.
17 is a cross-sectional plan view taken along the line XVII-XVII in FIG.
Fig. 18 is a side view of the sleeve of the pressure control valve, Fig. 19 is a side view of the sleeve and spool showing the spool, Fig. 20 is a side view showing the spool, and Fig. 21 is a sleeve and spool of the solenoid valve. Fig. 22 is an enlarged vertical side view of Fig. 22, Fig. 22 is a cross-sectional plan view of the filter, Fig. 23 is a front view thereof, Fig. 24 is a cross-sectional plan view showing the mounted state thereof, Fig. 25 is a circuit diagram of the control device, and Fig. 26. The figure shows 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 of the oil passage switching valve and the sleeve). Figure 27 shows the output oil pressure and the handle torque. Explanatory diagram showing the relationship with
Fig. 28 is an explanatory diagram showing the relationship between reaction force flange side hydraulic pressure (handle torque) and torsion bar twist angle, and Fig. 29 is an explanatory diagram showing the relationship between reaction force plunger side hydraulic pressure and output hydraulic pressure, 30th. The figure is an explanatory diagram showing the relationship between the handle torque and the torsion angle of the torsion bar,
FIG. 31 is an explanatory diagram showing the flow rate on the inlet side of the control system and the flow rate of each part in the control system. (1) …… Oil pump, (2) …… Oil passage switching valve,
(3) …… Power cylinder, (4) …… Oil tank,
(5) …… Reaction force piston, (7a) …… High pressure oil passage, (7b)
(7c) (7d) ... oil passage extending from the high-pressure oil passage (7a) to the reaction piston (5), (7e) (7e ') ... parallel oil passage,
(8a) (8b) …… Low pressure oil passage, (11) …… Changing over valve, (12) …… Pressure control valve, (13) …… Flow control valve, (a) …… Main orifice, ( b) ... the second orifice, (c) ... the fourth orifice, (d)
…… The first orifice, (e) …… the third orifice.

Claims (3)

[Claims] 1. An input shaft and an output shaft, which are coaxially rotatably supported in a housing and elastically coupled to each other via a torsion bar so as to be rotatable relative to each other, and the input shaft associated with a steering handle steering operation. And an oil passage switching valve that controls the supply and discharge of hydraulic oil to and from a power cylinder that applies an assisting force to the output shaft according to the relative rotation between the output shaft and the output shaft, and high-pressure oil that extends from the oil pump to the oil passage switching valve. Passage, a low-pressure oil passage extending from the oil passage switching valve to the oil tank, and part of the hydraulic oil flowing in the high-pressure oil passage is guided to the reaction force piston, and at least the reaction force piston is input by the oil pressure of the operation oil. In a power steering device including a reaction force mechanism that drives a shaft or an output shaft in a radial direction to restrict twist of the torsion bar, a power steering device extends from the middle of an oil passage extending from the high pressure oil passage to the reaction force piston. Parallel oil passage, a second orifice provided on one side of the parallel oil passage, a flow control valve for varying the discharge amount of hydraulic oil from both of the parallel oil passages according to the vehicle speed, and the same flow control A first orifice provided in an oil passage extending to the oil tank downstream of the valve to generate a main pilot pressure according to a flow rate, and the reaction piston upstream of the second orifice operating by the main pilot pressure. A power steering device, comprising: a pressure control valve for controlling the hydraulic pressure to the vehicle so that it is constant at each vehicle speed and becomes higher at higher vehicle speeds. 2. An input shaft and an output shaft, which are coaxially rotatably supported in a housing and elastically coupled to each other via a torsion bar so as to be rotatable relative to each other, and the input shaft associated with a steering operation of a steering wheel. And an oil passage switching valve that controls the supply and discharge of hydraulic oil to and from a power cylinder that applies an assisting force to the output shaft according to the relative rotation between the output shaft and the output shaft, and high-pressure oil that extends from the oil pump to the oil passage switching valve. Passage, a low-pressure oil passage extending from the oil passage switching valve to the oil tank, and part of the hydraulic oil flowing in the high-pressure oil passage is guided to the reaction force piston, and at least the reaction force piston is input by the oil pressure of the operation oil. In a power steering device including a reaction force mechanism that drives a shaft or an output shaft in a radial direction to restrict twist of the torsion bar, a power steering device extends from the middle of an oil passage extending from the high pressure oil passage to the reaction force piston. Parallel oil passage, a second orifice provided on one side of the parallel oil passage, a flow control valve for varying the discharge amount of hydraulic oil from both of the parallel oil passages according to the vehicle speed, and the same flow control A first orifice provided in an oil passage extending to the oil tank downstream of the valve to generate a main pilot pressure according to a flow rate, and the reaction piston upstream of the second orifice operating by the main pilot pressure. Is provided between the pressure control valve that controls the oil pressure of the oil passage to the vehicle to be constant at each vehicle speed and becomes higher at higher speeds, and the oil passage extending to the reaction force piston and the high pressure oil passage, and does not steer at high speed. Only in the vicinity of the neutral position, the pilot pressure generated between the second orifice provided in one of the parallel oil passages and the flow control valve operates in the closing direction to set the oil pressure of the oil passage to the reaction piston to a predetermined value. Price increase Power steering apparatus characterized in that it comprises a change-over valve which. 3. An input shaft and an output shaft, which are coaxially rotatably supported in a housing and elastically connected to each other via a torsion bar so as to be rotatable relative to each other, and the input shaft associated with a steering handle steering operation. And an oil passage switching valve that controls the supply and discharge of hydraulic oil to and from a power cylinder that applies an assisting force to the output shaft according to the relative rotation between the output shaft and the output shaft, and high-pressure oil that extends from the oil pump to the oil passage switching valve. Passage, a low-pressure oil passage extending from the oil passage switching valve to the oil tank, and part of the hydraulic oil flowing in the high-pressure oil passage is guided to the reaction force piston, and at least the reaction force piston is input by the oil pressure of the operation oil. In a power steering device including a reaction force mechanism that drives a shaft or an output shaft in a radial direction to restrict twist of the torsion bar, a power steering device extends from the middle of an oil passage extending from the high pressure oil passage to the reaction force piston. Parallel oil passage, a second orifice provided on one side of the parallel oil passage, a flow control valve for varying the discharge amount of hydraulic oil from both of the parallel oil passages according to the vehicle speed, and the same flow control A first orifice provided in an oil passage extending to the oil tank on the downstream side of the valve to generate a main pilot pressure according to a flow rate, and to the reaction piston upstream of the second orifice operating by the main pilot pressure. A pressure control valve for controlling the hydraulic pressure of the vehicle so as to be constant at each vehicle speed and to become higher as the vehicle speed increases, an oil passage extending downstream of the pressure control valve and an oil passage extending to the oil tank downstream of the flow control valve. The flow rate from the downstream side of the pressure control valve to the low pressure oil passage, which is provided in the middle of the connecting oil passage, is reduced corresponding to the increase in the area from the first orifice on the downstream side of the flow control valve to the low pressure oil passage. Passing Power steering apparatus is characterized in that third and comprises a orifice to be adjusted to increase.