JPS61129365A - Power steering device - Google Patents

Abstract

PURPOSE:To enhance the feeling of reaction over the whole range of running speed, by providing a vehicle speed responsive type flow control valve, and a bypass means for deenergizing an unloader valve upon high speed running of a vehicle. CONSTITUTION:When a vehicle comes to be in its high speed condition, a control device 15 receives a pulse signal from a vehicle speed sensor 14, and shifts a flow control valve 13 into the position H. Then the hydraulic pressure of an oil passage 7f comes to be lowest, which is transmitted to a pressure control valve 12. Therefore, the hydraulic pressure of the oil passage 7d comes to be highest, which is transmitted to a change-over valve 11 that therefore selects the position H. Thus, bypass passages 7b1, 7b2 are closed while passages 7c2, 7c3 are communicated to the passage 7b2 so that the hydraulic pressure from an oil pump 1 is fed into a passage selector valve 2 to increase the output hydraulic pressure by a set value. With this arrangement even if an loader valve 19 is closed, the hydraulic pressure of an oil passage 7d is held at a predetermined high level in the closing operation of the change-over valve 11.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to improvements in power steering devices used in automobiles.

(Prior Art) The present applicant proposed a high-pressure oil line that was transmitted from the oil pump to the oil passage switching valve by transmitting the information to the oil passage switching valve via the dynamic torque torsion bar of the steering handle, and from the oil passage switching valve to the oil tank. In a power steering device that operates a power cylinder in a predetermined steering direction by switching between an extended low-pressure oil passage and a part of the hydraulic oil flowing in the same high-pressure oil passage to a reaction piston to restrict twisting of a torsion bar, a bypass oil passage K that bypasses the orifice of the high-pressure oil passage;

The invention is characterized in that a change-over valve is provided that closes the bypass oil passage and increases the oil pressure in the oil passage to the reaction piston by a predetermined value only when the vehicle is near a neutral position where no steering is performed at high speed. A power steering device has already been proposed (if necessary, please refer to Japanese Patent Application No. 58-86599).

(Problems to be Solved by the Invention) In the power steering device, the bypass oil passage is closed only when the steering is not performed at high speed and near the neutral position, and the oil pressure in the oil passage to the reaction piston is adjusted to a predetermined value (+tsky). /- degree) and increase the steering wheel torque near the above neutral position to reduce the reaction force feeling (response) during minute steering at high speeds.
- However, if you continue to turn the steering wheel further to the right (or left), the output surface oil pressure of the oil passage switching valve (oil pump discharge pressure) will change to a quadratic curve as shown in Figure 16. The influence of this discharge pressure is directly reflected in the oil path of this control system, that is, the oil path to the reaction piston, and the 5 pilot oil path from the same oil path to the change over valve. The oil pressure in each oil passage increases, causing the change
Move the over valve to the open position (L position), open the bypass oil passage, and reduce the oil pressure in the oil passage to the reaction piston by the predetermined value above, reducing the reaction force feeling (response) during high-speed steering.・There was a frequent problem of unstable steering.

(Means for Solving the Problems) The present invention addresses the above-mentioned problems by transmitting the movement of the steering wheel through the torsion bar to the oil passage switching valve so that the movement is transmitted from the oil pump to the oil passage switching valve. The high-pressure oil passage extending from the oil passage to the oil tank and the low-pressure oil passage extending from the oil passage switching valve to the oil tank are operated to operate the power cylinder in a predetermined steering direction, and a portion of the hydraulic oil flowing through the high-pressure oil passage is used as a reaction force. In a power steering device that guides the piston to the torsion bar and regulates the torsion of the torsion bar, the main orifice (
α) A change-over valve that closes the t-detour bypass oil passage and increases the oil pressure in the oil passage to the reaction piston by a predetermined value, and a change-over valve that closes the bypass oil passage to the reaction piston and increases the oil pressure in the oil passage to the reaction piston at a high speed of a predetermined speed or higher. Completely close the oil passage leading from the low-pressure oil passage, increase the oil pressure in the oil passage to the scale capiston, and the pilot oil passage from the same oil passage to the change-over valve, and close the change-over valve. an unloading knob that closes the oil passage to the reaction piston when the pump discharge pressure increases due to steering, and an unloading knob that closes the oil passage to the reaction piston when the pump discharge pressure increases due to steering; The nosewheel steering device is characterized by having an unload valve bypass means that substantially deactivates the 9 valves, and its purpose is to reduce the feeling of reaction force throughout the entire range when driving at high speeds. The object of the present invention is to provide an improved power steering device that can improve steering response (response = steering sensation).

(Embodiment) Next, an embodiment of the power steering system according to the present invention shown in FIGS. 1 to 15 will be explained. First, to explain the outline with reference to Fig. 1, (1) is an oil pump driven by an engine (not shown);
1) is an oil pump with a constant flow rate (about 7 l/min) and a variable discharge pressure (5 kg rad to 70 k19./y). In addition, (2) is a four-way oil passage switching valve (rotary valve), (3) is a steering/thrower cylinder, (
4) is an oil tank, (5) is a plurality of reaction pistons,
(6) is formed behind each reaction force piston (5): +, (7α□) (7α2) is the oil pump (
1) to the oil passage switching valve (2), nine high pressure oil passages, (8
α) is from the same oil passage switching valve (2) to the above oil tank (4)
(9α) and (10α) are oil passages extending from the oil passage switching valve (2) to the power cylinder (3);
(α) is the main orifice provided between the high pressure oil passages (7α□) (7g2), and C7h□) (7b2) are the high pressure oil passages (7α1) (7a1) (on the upstream and downstream sides of the main orifice (α)).
7α2) K-connected bypass oil passage, αυ is a change over valve (COV) that constitutes a hydraulic pressure increasing means inserted between the bypass oil passages (7b1) (7b2), and αυ is the change over valve Oil passage (7b) on the upstream side of the valve housing
1) is connected to the pressure control nozzle 2 via oil passages (7C1) and (7C2), (13) is the flow rate control valve, and (7d) is the oil passage extending from the pressure control valve (lz). (
A pair of parallel oil passages (7e) (7g') branched from 7d) extend to the flow rate control valve αj. Also (7cm3
) is the oil passage extending from the H@ port of the change over valve αυ to the wave passage (702”), (C) is the third orifice provided in the same oil passage (7C3)K, and C9 is the oil passage (
Unlow P valve interposed between 7C1) (7C2),
(7d1) is a sub-4 pilot oil passage extending from the middle of the oil passage (7d) to the pressure control valve C13, Cod2)
is from the middle of the oil passage (7d) to the reaction piston (5).
(b) is the oil passage extending to the chamber (6) behind the oil passage (7#,).
is the COW/COW/
(Ilot oil passage, (7f) is the flow control valve (13)
The oil passage extends from the above-mentioned low pressure oil passage (8h), (→ is the first orifice installed in the middle of the same oil passage (7f), and (7f1) is the oil passage on the upstream side of the first orifice (d'I). A main pilot oil passage extending from (7f) to the pressure control valve α2, α
The mount is the vehicle speed sensor, C9 is the control device, αe is the ignition switch, and η is the ignition coil (18α)
(18b) to the electromagnetic coil of the flow rate control valve r13, the vehicle speed sensor a4 detects the vehicle speed, and the resulting .xi. pulse signal (pulse signal corresponding to the vehicle speed) is sent to the t-control device. It is designed to be sent to α9. Next, the next control device a9 controls a flow control valve to apply a current corresponding to the same pulse signal (a current corresponding to the vehicle speed from zero current (i-O) at a high speed of a predetermined speed to a current maximum current C1-1> when stopped). 0's electromagnetic coil too? ), and the plunger f53 of the flow control valve a3 and the spool 6υ are held at predetermined positions according to the above-mentioned current value.

Next, the oil passage switching valve (2) change over valve, pressure control valve α2, flow rate control valve (13 unload valve, housing 9t) will be explained in detail with reference to FIGS. 2 to 15. The box in Figures 2 to 6 is the valve housing.
Each of the above-mentioned valves (2) aυa2 (13) is built into the same valve housing (manufactured by Co., Ltd.).

First, the oil passage switching valve (see Figure 21t-g2, specifically, Ql) is an input shaft operated by a steering wheel (not shown), and (2) in Figure 2.3 is an upper and lower input shaft. The cylinder block, Ca, which constitutes the output shaft that is rotatably supported in the Ginolup housing by a bearing, is a torsion bar inserted into the input shaft cdυ, and the upper part of the torsion bar device is connected to the input shaft Qυ. The upper part of the torsion bar (A) and the lower part thereof are fixed to the cylinder block @, respectively, so as to allow the relative rotation angle difference between the input shaft I2υ and the cylinder block (to) due to the torsion of the torsion bar (A). It is configured. Further, (21α) is a plurality of vertical grooves provided on the lower outer circumferential surface of the input shaft Qυ, and the cylinder block g3 is provided with cylinders facing each of the vertical grooves (21α)K, and each cylinder The reaction pistons (5) are fitted into the reaction pistons (5), and the projections are engaged with the vertical grooves (21cL) at the tips of the reaction pistons (5). The chamber (6) behind each reaction piston (5) is formed between the cylinder block (1) and the valve housing (2) and communicates with the annular groove (1).

7'C (23α) is a pinion integrated with the cylinder block (2), (24α) is a rack meshed with the same pinion (23α), C24) is a rack support, the can is a cap, and (C) is the same cap and the sleeve of the oil passage switching valve (2) fixed in the valve housing (2) directly above the cylinder block (2); 28g) (28b)
(28') is the oil passage provided on the outer peripheral surface of the sleeve (to), the valve body is inserted between the sleeve □□□ and the input shaft Qυ, <234) is the valve The pins (27α), (27h), and (27C) connecting the lower end of the body and the upper end of the cylinder block are oil passages provided on the outer peripheral surface of the nozzle body.
□ In the above configuration, when the steering handle is in the neutral position, the high pressure oil passage (7α) is connected to the input shaft Qυ via the oil passage (27α) of the valve body and the oil passage (28α) of the sleeve ■. The hydraulic oil from the oil pump (1) flows through the high pressure oil path (7α) → oil path (28α) → oil path (27α) →
The oil circulates from the chamber @ (the oil path between the oil path (27 cL) and the chamber (A) is not shown) → low pressure oil path (8α) → oil tank (4) → oil pump (1). It has become. Also, when the steering wheel is turned to the right and the input shaft +211 is rotated to the right relative to the valve body @, the high pressure oil passage (7α) is connected to the oil passage (27α) (27h) of the valve body f@ and the sleeve ( 2) Oil passage (
28A) to the oil passage (9α) of the power cylinder (3)
, the low pressure oil passage (8α) connects the chamber (to), the oil passage (27C) of the valve body (5), and the oil passage (2) of the sleeve (to).
8C) and the oil passage (10
α), and the hydraulic oil from the oil pump (1) is connected to the high-pressure oil passage (7α) → oil passage (27α) → oil passage (
28, 6) → Oil passage (9α) → The oil in the right chamber of the power cylinder (3) is sent to the left chamber of the power cylinder (3), while the oil in the right chamber of the power cylinder (3) is sent to the oil passage (10a) → Oil passage (28C) → Oil passage ( 27C)→Chamber exhaust→Low pressure oil passage (8α)→Return to tank (4), the piston rod of the power cylinder (3) moves to the right, and steering to the right is performed. Also, if you turn the steering wheel to the left and rotate it to the left relative to the input shaft ant valve body fin, the high pressure oil passage (7α) will move between the valve body oil passage (27α) and the sleeve (toward) oil passage. (
28C) of the power cylinder (3).
α), the low pressure oil passage (8cL) is connected to the oil passage (27A) between the chamber wall and the valve body, and the oil passage (28A) between the sleeve (toward).
A) and the oil passage (9α) K of the power cylinder (3).
, are in communication with each other, and the hydraulic oil from Oil Bon Pro) is passed through the high pressure oil path (7α) → oil path (27a) → oil path (28C) →
Oil passage (10α) → is sent to the right chamber of the power cylinder (3), while oil in the left chamber of the power cylinder (3) is sent to the oil passage (9α).
) → Oil passage (28b) → Oil passage (27A) → Chamber wire →
The low pressure oil passage (8α) is returned to the tank (4), and the piston rod of the power cylinder (3) moves to the left, so that leftward steering is performed.

Next, the change O+-+ constituting the oil pressure increasing means;
S valve (11) and unroll r pal 7' (19t-
To explain specifically, the same change over valve αυ
As is clear from FIGS. 3 to 7, is interposed between the bypass oil passages (7h1) (7b2) of the main orifice (α). The change over valve aυ has an annular groove (30b
) corresponds to a part of the oil passage (7C, ), and the annular groove (30C) corresponds to a part of the oil passage (7g1), respectively) t-The provided spool c! It has 13. In addition, the unload 9 valve a9 incorporated in the change oats 5 valve body is tightly fitted to the inner circumferential surface of the spool (to), and is axially inserted into the fixed sleeve (to) and the same sleeve (to). It has 9 spools (to) that are fitted to allow movement of the spools, and the spools (to) have oil passages C7h, ) (7C1) and oil passages (74
? 2) An annular oil passage (36a) that communicates with and shuts off the
(See Figure 7). In addition, 611 is a fixed cap fixed to the nozzle housing (A), (to) is a movable cap fitted under the fixed cap 01) so as to be movable in the axial direction, and (to) is each of the same caps 0υ (To)
The spring inserted between the above movable cap (to)
and the above-mentioned unloading 9 valve (19 spool (to)) with a hole inserted between Nolot oil passage (7g1) (
(see Figure 1) increases, the spool (to) moves to the 4th position.
It rises from the position shown in the figure to the position shown in Fig. 56 against the spring (to) to cut off the bypass oil passages (7b1) (7h2), and when the oil pressure of the pilot oil passage (711) decreases. , the spool (end) descends due to the spring (end),
The bypass oil passages (7h1) and (7h2) are communicated with each other. Also, when the oil pressure in oil passage C741) (see Figure 1) increases, the spool (to) rises from the position shown in Figure 4.5 to the position shown in Figure 6 against the spring (2), and
7b1) (7C,)
When the oil pressure of 7h1) decreases, the spool (to) will release the spring (
B) K] It is a trap that descends and connects the oil passages (7A,) (71?1). The outer circumferential surface of the spool (end) of the change oats valve αυ is finished to the micron level, but if the inner circumferential surface is also finished to this degree, it will not be easy to process, so the unload valve α9's The inner circumferential surface on which the sleeve (to) slides is made of brass,
A soft metal sleeve made of aluminum or the like is tightly fitted and fixed to facilitate finishing of the inner circumferential surface of the spool.

Next, to specifically explain the pressure control valve α2, the pressure control valve α2 is composed of a sleeve (41, a spool (41), a cap G43, a stopper (43, and these It has a spool head, a cap (spring G44 interposed between the four springs), and an orifice (d-) provided in the spoon.The spool head also includes:
As shown in Figure 11, there are three annular grooves (41α') (4
1b) (41C) is provided, and the annular groove (41α) is connected to the change oil passage (7h1) (12).
Oil path branched from the upstream side of over valve αυ (7C1)
It is facing (7C2). In addition, (414) is a chamber that extends upwardly within the spool @D from the orifice <d'I, and (41g) is an oil passage connecting the chamber (41d) and the annular groove (41'). (41
1i) (41g) (41C) is a part of the low pressure oil passage (8h)), and the annular groove (41c') is located directly above the valve body slope of the oil passage switching valve (2) shown in Figure 2. The valve housing (
A) side low pressure oil passage (8A) is opposite to K.

In addition, as shown in FIGS. 12 to 15, the sleeve QQK has cutout portions having through holes from the upper part to the lower part with different phases in the circumferential direction on the outer circumferential surface, that is, through holes (4
0α') T-notch (401 and through hole C40b'
) with a notch (40A) and a through hole (40'> (4
0c'') fc notch (40C) and orifice*(h
)t-4 notches (40d) are provided.

Each of the above grooves etc. has a hole (40α') having a through hole (40α').
) connects the annular groove (41C) of spool 01) and the low pressure oil passage (8h) on the valve housing (a) side, and connects the through hole C
A notch (40b) with a groove (40b') connects the annular groove (41α) of the spool and the oil passage ('IC2') on the valve housing ω side.
), and the notch (40C) with the through hole (40C') (40c'') connects the annular groove (4m) of the spool (4m).
1α) (41j) t connected, orifice <h> 1-
The notch (40ct) has a spool (4m) O annular groove (
41j) and the oil passage (7e) on the valve housing (end) side, and the notch (40C) with through holes (40t') (40c'') connects with the annular groove (41j) of the spool holder (Fig. 466). Oil passage (7d) on the valve housing ■ side shown in
) are connected. Then, the oil that came out from Oriais (14) to the chamber (41d) of spool I is in the oil path (41g
) → Annular groove (4C) → Through hole (40α') → Notch (4
0α)→Low pressure oil passage on the valve housing ■ side (8A) t
Hydraulic oil enters the through hole (404') through the oil tank (4)K through the oil tank (4)K, and from the bypass oilway Cab1) through the oilway (7C1) (7C,)t-through the notch (40A)K.
→ Annular groove (41α) → Notch (40C) - + Through hole (4
(C') → Annular groove (41b) -+ Through hole (40t')
→ Notch (40g) → Oil passage of valve housing ■ (7c)
L) through the flow control valve (13) and the reaction piston (5
) is configured to face in the direction of Also, a part of the hydraulic oil flowing inside the annular groove (41A) is orifice <b>.
→ Notch (40d) → Oil passage on the valve housing ■ side (7
e), which acts as a pilot pressure behind the spool (to) of the change-over valve housing (see Cuel in Figure 5), and an oil passage (to which is provided at the rear end of the spool). 30A) (see Fig. 7) - The flow rate control knob (13
It is now heading in the direction of.

Next, the flow rate control valve fi3 will be explained in detail.
As is clear from Fig. 45.6.8, the flow rate control valve 0 is disposed directly under the pressure control valve (2) so that their axes coincide with each other.
j is a sleeve (to), a spool 6υ, a plunger 51 made of a non-magnetic material, a member made of a magnetic material (not shown) integrated with the plunger 51, and the spool 6υ connected to the plunger 63.
The lock nut 54) is tightened to fix the pressure control valve αa, and the seat plate (to) that contacts the sleeve (4G) and the backup spring (to) interposed between the seat plate (to) and the sleeve (a) are tightened. ) and an electromagnetic coil 6η, and as shown in FIG. It has an oil passage (50A) communicating with the oil passage (7t).Also, the spool 61)K
is an annular oil passage (51g) with an oblique groove (51α')
The plunger 6a has a through hole (51A), an annular oil passage (510), and a through hole (51j).
51A) An oil passage (52α) communicating with (51d), a through hole (52A), and an axial oil passage (52C) are provided, respectively. As already mentioned, the oil passage (7 cL) on the valve housing ■ side shown in Figure 4a6 → oil passage (7 g'
) from the flow control valve α enters the oil passage (505 in Figure 8), and then flows from the oil passage (7cL) on the valve housing (A) side to the oil passage (7-) shown in Figure 446. The hydraulic oil flowing from the flow control valve C13 to the flow control valve C13 flows through the oil path (50'
)to go into. However, Figure 8 shows the state at high speed.
In this state, the oil passage (5'1α) (51α and the oil passage (51C) are closed by the spool 51 of the flow rate control valve (13)). However, when the speed of the vehicle decreases, the control device α9 receives a pulse signal from the vehicle speed sensor I, sends a current corresponding to the vehicle speed at that time to the electromagnetic coil mark of the flow control valve α, and the plunger 5
z and spool 6υ descend from the upper limit position, and the oil passage (
51α) (51α') connects the oil passage (50b) to the oil passage (5C)
are connected to the oil passage (50α), respectively, and the oil passage (7g')
Hydraulic oil entering the oil passage (50b) from the oil passage (51α')
Hydraulic oil enters oil passage (52α) via oil passage (51α) → oil passage (51j), and enters oil passage (50α) from oil passage (7e) → oil passage (51C) → oil passage (51d). Via the oil road (5
2α), and then from the same oilway (52α) to the oilway (52
A)→Go to Oriais (d) via oil route (52C).

Note that the slope in Figure 2.3 is the central axis of the oil passage switching valve (2).

(action).

Next, the operation of the power steering device will be explained. The output oil pressure of the oil passage switching valve (2) (discharge pressure of the oil pump (1)) Pl) is determined by turning the handlebar from the neutral position to the right or left, and adjusting the relative angle of the input shaft QJ) to the valve body. If it becomes larger, it will rise in a quadratic curve as shown in (m) in Figure 16. This oil pump (1) is pushed in the direction of the arrow in FIG. At the same time, the hydraulic pressure P0 of the hydraulic oil passing through the annular groove (41j) t of the spool (41) pushes the spool 01)f in the direction of the arrow in FIG. 11 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 @9 gradually rises against the spring 04, and the through hole (44
0A') gradually becomes smaller, and when the hydraulic pressure pushing in the direction of the arrow above and the spring force are balanced, the spool @υ stops. In this state, the oil pressure PC of the oil passage (7d) (reaction piston side chamber (6)) is the lowest. Turn the handle further to the right (1& is left) and turn the oil path (7α) (
7b) When the oil pressure P of (7C) further increases, the pressure control valve α2 increases the oil pressure Pp acting on the annular groove (41b).
Due to the difference in the pressure receiving area of the spool G11), the through hole (4
0A') is further moved in the closing direction, and the oil pressure Pc of the oil passage (7t) is maintained at the constant low level. Therefore, when increasing the relative angle to obtain a large output oil pressure PF, the torque must be increased by the torque determined by the torsion angle of the hydraulic pressure PC and dosion bar device in the reaction piston side chamber (6). (see Fig. 6), during the above stationary cutoff, the oil pressure 'PC of the oil passage (7d) is low, as already mentioned, and the spool (end) of the change-over valve αυ is affected by the elasticity of the spring (end). (Also held at the L position in FIG. 1 and the position in FIG. 4, opening the bypass oil passage C741)<7h,'). At this time, the spool (to) of the unload valve device is held in the position shown in Fig. 4 by the elasticity of the spool (to),
C□) (7C2) t-open. Note that the change over valve αυ in FIG. 1 shows the H position.

When the automobile enters a low-speed running state, the control device α9 receives a pulse signal from the vehicle speed sensor a4, and sends a current corresponding to the vehicle speed at that time, for example, −1 α8, to the flow rate control valve a3. plunger 62 and spool 61)
It is raised nine distances from the t-lower limit position corresponding to the above current value (moved to the right in FIG. 1), and the opening amount of the sleeve opening side oil passages (50α) (50b) shown in FIG. 8 is reduced. Therefore, the flow rate coming out of the flow control valve (13t) will be lower than the flow rate from the oil passages (50α) (50b) when the vehicle is stopped, and the oil pressure in the oil passage (7f) on the upstream side of the oriswiss (d) will decrease. When stopped, the steering wheel will also become lower.If you start turning the I-wheel to the right (or left) at low speeds, the oil passage (7
d) Hydraulic pressure PC starts to rise. Then, the oil path (7
f) oil pressure also increases. This oil pressure is applied to the main pilot oil path (
7f), the spool @9 (small diameter end of spool @D) of the pressure path control valve a2 is viewed, and the spool is pushed in the direction of the arrow in FIG. At the same time, the hydraulic oil passing through the annular groove (4]j) of the spool presses the spool in the direction of the arrow shown in Fig. 2 due to the difference in pressure receiving area.

On the other hand, the spring ■ side passes through the low pressure oil passage (8b) K, and the spool @D gradually rises against the spring K, and the through hole <
40b''') gradually decreases, and when the hydraulic pressure pushing in the direction of the arrow above and the spring force are balanced, the spool (41) stops, but the hydraulic pressure pushing the small diameter end of the spool head is the same as when the spool is stopped. The height of the oil passage (7d) (reaction piston side chamber (6)) is also low, and the amount of rise of the spool (4υ) is correspondingly small (the opening amount of the through hole (40b') is correspondingly large). The oil pressure Pc becomes higher than when the vehicle stopped.This condition remains the same from then on, and the steering wheel is further turned to the right (or left) to open the oil passage (°7α1)C7h,)C
When the oil pressure Pp of TCl)CrO2) further increases and the oil pressure of the annular groove (41b) is about to further increase, the pressure control valve H moves the spool cut- further to control the opening degree of the through hole (4OA'). The oil pressure PC in the oil passage (7 cL) is maintained at a high constant level even when the vehicle is stopped. Therefore, by increasing the relative angle, a large output oil pressure Pp
When obtaining t-, the steering torque T also increases (as when the vehicle is stopped), but it does not become as large as when the vehicle is at high speed as described later.

In the above-mentioned fixed-off state or in the low-speed running state, when the handle is turned significantly, the pump discharge pressure becomes large and flows through the pressure control valve a3 and from the flow rate control valve αj to the low-pressure oil passage (8b). Hydraulic oil increases. At this time, the oil pressure on the upstream side of the orifice (4) increases, but due to this effect, the oil pressure acting on the oil passage (7g1) at the end of the spool (to) of the change-over valve housing increases. Similarly, the change oats Z has a tendency to increase due to the oil pressure.
- The valve αυ may operate upward, making the operation unstable, and the oil pressure of the reaction piston 1N chamber (6) becomes large, which causes the handle torque to become large. For this reason, an orifice <h> located on the upstream side of the oil passage (7g□) is provided so that the oil pressure in the oil passage (7g□) is maintained lower than the COV operating oil pressure and the operation is stabilized. ing.

When the vehicle enters a high speed state at a predetermined speed, the control system ff
1tQs receives the Norse signal from the vehicle speed sensor α, sends a current of imo, 5 (or i<0.5) to the flow rate control valve αj, and causes the plunger 63 and spool 6υ to
1 to the upper limit position (in FIG. 1, it is moved to the H position shown in the figure), and the oil passage (50α) (soh) of the sleeve (to) in FIG. 8 is fully closed. At this time, the flow rate from the flow rate control valve (13t) becomes zero, so the oil pressure at the wave path on the upstream side of the oriice (d) becomes the lowest.

This oil pressure is transmitted to the spool (4 m) (small diameter end of spool 0) of the pressure control valve σ2 via the main pilot oil passage (7f), so the urging force pressing the spool is zero. become. At the same time spool (41)
The hydraulic oil passing through the annular groove (41A) pushes the spool (41) in the direction of the arrow in FIG. 11 due to the difference in pressure receiving area.

On the other hand, the spring [4g4 is connected to the low pressure oil path' (8A)]
, the spool Ill gradually rises against the spring ■, the opening degree of the through hole (40) gradually becomes smaller, and when the hydraulic pressure pushing in the direction of the arrow above and the spring force combine, the spool 0
D stops. However, the hydraulic pressure pushing the small diameter end of the spool (4a) becomes zero and the amount of rise of the spool Ql is very small (the opening amount of the through hole (40A') is the maximum), and the oil passage (7d) The oil pressure PC of the C reaction piston side chamber (6) becomes the highest. This oil pressure is transmitted to the spool (to) of the change over valve (111) through the orifice (b) and the pilot oil passage (7g1), and the spool (to) moves from the position shown in Fig. 4 to the position shown in Fig. 5. (In Figure 1, H position et- is selected)
) (7b') is closed and the oil passage (7C2) (
7Ca) and the oil passage (7h2) are connected, and the hydraulic oil from the oil pump (1) is sent to the oil passage switching valve (2) via the main orifice (cL), so that the output oil pressure Pp is equal to the set pressure. Rise. This means that even when not steering at high speed (steering wheel in neutral position), oil passages (7α1) (7b1) (7b
2) Hydraulic pressure Pp of (7C1) (7C2) (7C3)
(see Pp1 in Figure N), this oil pressure is applied to the chamber (6) on the opposite side of the piston via the pressure control valve α2 and the oil passages (7d) (7d1). ), which improves the feeling of reaction force (response) during minute steering at high speeds. If you continue to turn the handle further to the right (t or left), the oil passages (7a1) (7h1) (7b2) (
7e1) (7c,) (7e,) The oil pressure Pp further rises (for example, rises to about 15 to 9/-) and the oil passage (
7d) The oil pressure P further increases during the above-mentioned operation, and in this case, it increases by the above-mentioned set pressure, resulting in an overall higher pressure than during stationary shut-off operation. Then, the oil pressure in the oil passage (7e) on the downstream side of the orifice (A) increases beyond the set value.

At this time, in the power steering device described in the specification of Japanese Patent Application No. 58-86599,
The force acting on the spool (to) through spring C1
3, the spool (to) of υ to the changeover valve selects the L position, the pino-signature oil passages (7b1) (7b2) are opened, and the reaction piston (5)
The oil pressure in the oil path (7 cL) to the specified value (+151'9/
- degree). In addition, this was done because
Orifice (α) and change over hole αυ
The increase in pressure caused by the closing of the is effective in improving the feeling of reaction force at high speeds.
2>E % Power cylinder (3) K causes pressure loss, but when using K as above, pressure loss occurs during high-speed steering that requires output above a certain value in the power cylinder (3). This is because it is possible to significantly improve the reaction force feeling only near the neutral position of the steering wheel where the output oil pressure is low, without causing this. However, in this case, there are six problems that make the steering unstable except near the neutral position of the steering wheel.
In the present invention, oil passage (7α1) (74,) (7C construction) (7
-2) When the oil pressure Pp increases as described above, the changeover valve I is constantly connected to the oil passage (7A1') and C
ab,) t- is closed, so the oil pressure to the reaction force screw) y (5) is always kept high, that is, the handle torque T is kept high.

Furthermore, during stationary operation and low speed operation, if the pump discharge pressure Pp becomes higher than the maximum control pressure by the flow rate control valve C13, for example 12 to 131QF/-, for example 15 to 9/-, the unload valve ( lI is closed. Therefore, the pressure downstream of the unload valve member becomes all O, and the spool (41) of the pressure control valve a5 (regardless of the flow rate control valve L3) is closed by the spring force. It is lowered to the lower end as shown in the figure.

At this time, the oil pressure supplied to the reaction piston is O.
The handle torque is the minimum value (lightest) with 6 torsional torques of the torsion bar device only. On the other hand, during high-speed operation, even if the unlower valve is closed in response to steering, the oil passage (703) is closed as described above due to the closing operation of the changeover valve αυ. 7C, ) (7b
,) through the oil passage (7α2)K, and the same oil passage (7α2)
g2) oil pressure Pp is transmitted to the oil passage (7C3), and the oil pressure Pp of oil passage (7C3) is transmitted to the oil passage (7C3).
7d) oil pressure PC continues to be held at the highest constant level.

Therefore, when the relative angle is increased to obtain a large output oil pressure, the steering torque is increased, and the reaction force feeling (response and steering sensation) is improved over the entire range during high-speed running.

It should be noted that the working oil pressure of the unload valve α9 is preferably set low when driving at low speeds and high when driving at high speeds; Slightly large1
If set to about 5klI151, the same pressure will often be exceeded when running at low speed and the unload valve will close easily, and the same pressure will rarely be exceeded when driving at high speed and the unload valve will open and close. It is less affected by fluctuations in handle torque due to

(Effects of the Invention) As described above, the present invention provides a high-pressure oil passage and an oil passage extending from the oil pump to the oil passage switching valve by transmitting the movement of the steering handle to the oil passage switching valve via the torsion bar 2-. The low-pressure oil passage extending from the switching valve to the oil tank is switched to operate the power cylinder in a predetermined steering direction, and a portion of the hydraulic oil flowing through the high-pressure oil passage is guided to the reverse piston to restrict twisting of the torsion bar. In the power steering device, the change-over valve closes a bypass oil passage that bypasses the main orifice (α) of the high-pressure oil passage and increases the oil pressure in the oil passage to the reaction piston by a predetermined value; At high speed, the oil passage from the middle of the oil passage to the reaction piston to the low-pressure oil passage is completely closed, and the oil pressure of the oil passage to the intermediate capiston and the Neulot oil passage from the same oil passage to the change-over valve is reduced. a flow rate control valve of the vehicle speed reactor that increases the change-over valve to maintain the change-over valve in a closed position, an unload valve that closes the oil passage to the reaction piston when the pump discharge pressure increases due to steering, and a predetermined At high speeds, the above-mentioned nine unload valves are substantially inactivated (it is equipped with a through unload valve bypass means, and the above action is performed, so at high speeds, the change over φ valve is closed and always You can control the steering wheel in the direction of maximum torque,
Improves steering stability. In addition, at low speeds, the change over valve is open, and the steering torque can be constantly controlled to a small value, and when steering, the unload valve is closed, which further reduces the steering torque and improves the feeling of lightness.

In addition, even though the unload valve is closed during high-speed steering, the unload valve 9 pass means (oil passage 7b2°7C3,
7C2)) ensures the oil pressure supply to the reaction piston, which also has the effect of improving steering stability.

Although the present invention has been described above with reference to embodiments, it goes without saying that the present invention is not limited to these embodiments, and that various design modifications can be made without departing from the spirit of the present invention. . For example, as shown in Fig. 17, unload valve a! 1 may be provided outside the change 1 over valve aυ. Note that (32 in FIG. 17 is a stopper).

As shown in Figure 18, a valve (19) that opens only during high-speed steering is installed in the bypass oil passage that bypasses the unload valve (19
A shaft may be provided to communicate the oil passage C7h□) (7C,) and the COV pilot oil passage (7e s ) during high-speed steering. As shown in Figure 19, the plunger 52 of the flow control valve α3 is connected to the 9th oil passage (52C).
((71)) (see Figure 4a6) and connect the oil passage (7e) and oil passage (7g') (52α) to the spool 6.
Oil passage (small diameter part) (51') provided at the tip of υ ((7f
)) may communicate with the orifice (d) side. Madai m diagram (drawing showing the low speed neutral position) and the second
FIG. 1 (drawing showing the high-speed neutral position) is another embodiment applied to the power steering device already proposed, and in this case also, the same effects as the power steering device shown in FIGS. 1 to 15 are obtained. can be achieved.

[Brief explanation 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 longitudinal cross-sectional side view showing an oil passage switching valve portion thereof, and Fig. 3 is a transverse plane of the oil passage switching valve portion. Figure 456 is a vertical sectional side view of the change over valve, pressure control valve, flow rate control valve, and unload valve;
Figure 7 is an enlarged longitudinal side view of the Cheno t) Oates valve and unload valve, Figure 8 is an enlarged longitudinal side view of a part of the flow control valve, and Figure 9 is an enlarged longitudinal side view of the pressure control valve. FIG. 10 is a plan view of the pressure control valve; FIG. 11 is a longitudinal side view taken along the line XI-XI in FIG. 10; FIG. 13 is a cross-sectional plan view taken along line 1, Fig. 13 is a cross-sectional plan view taken along arrow ■-hire line in Fig. 11, and Fig. 14 is a cross-sectional plan view taken along arrow xrv-xtv in Fig. 11.
A cross-sectional plan view along the line, Fig. 15 is taken from Fig. 11 in the direction of the arrow X.
FIG. 16 is a cross-sectional plan view taken along the line V-XV, FIG. 16 is an explanatory diagram of the operation of the present power steering device, FIG. 17 is a longitudinal side view showing another example of the unload valve, and FIG. 18 is a diagram of the unload valve. Hydraulic circuit diagram showing still another embodiment, 1st
FIG. 9 is a longitudinal sectional side view showing another embodiment of the flow control valve;
20 and 21 are longitudinal sectional side views showing other embodiments applied to the power steering device already proposed by the applicant. (1)...Oil pump, (2)...Oil passage switching valve,
(3)...←-cylinder, (4)...oil tank, (5)...reaction piston, (7α1) (7z2)
-High pressure oil line, ('11) (7c1) (7c2) (7d)
(7d2)...An oil passage extending from the high pressure oil passage (7α1) to the reaction piston (5), (7b2) (7C3)...An oil passage that holds the change-over valve αυ in the closed position,
(8g) (85)...Low pressure oil path, αυ...Change over valve, a3...Flow rate control valve, (1
1... Unload valve, (α)... Main orifice, (h)... Orifice.

Claims (1)

[Claims] (1) The movement of the steering wheel is transmitted to the oil passage switching valve via the torsion bar, and a high pressure oil passage extends from the oil pump to the oil passage switching valve, and a low pressure oil passage extends from the oil passage switching valve to the oil tank. In a power steering device that controls torsion of a torsion bar by switching the power cylinder to actuate a power cylinder in a predetermined steering direction and guiding a part of the hydraulic oil flowing through the same high-pressure oil passage to a reaction piston, the main orifice of the high-pressure oil passage (a) a change-over valve that closes a bypass oil passage that bypasses the oil passage to increase the oil pressure in the oil passage to the reaction piston by a predetermined value; Fully close the oil passage leading from the low pressure oil passage to the reaction piston and increase the oil pressure in the pilot oil passage from the same oil passage to the change over valve to close the change over valve. an unload valve that closes the oil passage to the reaction piston when the pump discharge pressure increases due to steering, and an unload valve that closes the oil passage to the reaction piston when the pump discharge pressure increases due to steering; A power steering device characterized by comprising an unload valve bypass means for automatically deactivating the power steering device.