JPS63110072A - Power steering device - Google Patents

Abstract

PURPOSE:To improve response property by enabling a valve mechanism work by rectilinear movement part of a gear mechanism, and by having the rectilinear movement part and a piston rod move in a body in the same direction so as to enable the subtle changing operation of the valve mechanism. CONSTITUTION:A gear mechanism 2 consisting of a rack 2a and a pinion 2b is provided at the tip end part of a steering handle axis 1, and the rotary movement of a handle is converted to the rectilinear movement by the gear mechanism. A shaft 5 is slidably inserted in a bush 12, and a pin 16 which is connected to a spool valve 14 is engaged with a spindle of the shaft 5. Four ports 18a-18d are provided at the spool valve 14, and 18a among them constitutes an inflow port of pressure oil from a hydraulic pump, 18b constitutes an outflow port of pressure oil to an oil tank, 18c constitutes an inflow port to a chamber B of a cylinder 7 and 18d constitutes an inflow port to a chamber A of the cylinder 7.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a power steering device, and more particularly to a power steering device that can control the supply and discharge of pressure fluid to and from a power cylinder with high precision.

(Prior Art) Generally, a power steering device includes a rotary valve between an input shaft on the steering wheel side and an output shaft on the steering wheel side, and the steering force from the steering wheel is directly applied to the rotary valve. The signal is transmitted to one control valve element of the valve, and is also transmitted to the other control valve element via a flexible member such as a torsion bar, and the rotary valve is switched according to the relative rotational deviation between them, and the hydraulic pump outputs the signal. The supply and discharge of pressure oil sent to the power cylinder on the output shaft side is controlled, and the steering force amplified by this power cylinder is transmitted to the output shaft via a gear mechanism consisting of a rack and pinion.

(Problems to be Solved by the Invention) In the conventional power steering device having the above configuration, the steering force from the steering handle is transmitted from one control valve element of the rotary valve through a flexible member such as a torsion bar. Since the signal is transmitted to the other control valve element, it is difficult to perform delicate switching operations on the rotary valve.Furthermore, the amplified steering force is transmitted to the output shaft via a gear mechanism, so there are many connections, which can cause problems such as backlash. There are problems not only with response delays due to play in the steering wheel and high costs due to an increase in the number of parts, but also with the difficulty of manual steering operation if an abnormality occurs in the steering hydraulic system. Further, since the input shaft and the output shaft are arranged to intersect with each other via the gear mechanism, it is necessary to take up a large installation space, and the types of vehicles to which the system can be applied are limited.

In view of the above-mentioned points, an object of the present invention is to obtain a power steering device which can be downsized by reducing the number of parts and can also perform delicate switching operations of a valve mechanism.

[Means for Solving the Problems] The power steering device of the present invention includes a gear mechanism that converts rotational motion of a handle shaft into linear motion, and a gear mechanism disposed in the same direction as the movement direction of the linear motion portion of this gear mechanism. a cylinder fixed to the vehicle body side; a hydraulic valve fixing block fixed to the piston bush of the cylinder and movably supporting the linear motion section; A valve mechanism is provided that is operated by the moving section to supply pressure oil from the hydraulic pump to the cylinder and to cause the piston rod of the cylinder to expand and contract in the same direction as the moving direction of the linear moving section.

[Effect]

In the present invention, since the valve mechanism is operated by the linear motion part of the gear mechanism, the ratio of the number of teeth of the gear mechanism, that is, the transmission ratio, is set larger, that is, the number of teeth is greater than the number of teeth of the rotation motion part on the handle shaft side. By setting the linear motion part to have a large number of teeth, delicate switching operations of the valve mechanism are possible, and the piston rod of the cylinder controlled by the human power shaft consisting of the linear motion part and the valve mechanism is Since the output shaft, which consists of .

〔Example〕

Hereinafter, the power steering device of the present invention will be explained based on the drawings. FIG. 1 is a front view showing the overall configuration of the apparatus of the present invention, and FIG. 2 is an enlarged perspective view showing the main parts thereof. In the figure, (1
) is the steering wheel shaft with a transmission ratio of approximately 12 at its tip.
:Rack (2a) and pinion (2b) set to 1
A gear mechanism (2) is provided, and the rotational movement of the steering handle shaft (1) is converted into linear movement by the gear mechanism. Reference numeral (3) is a steering boosting mechanism, which, in conjunction with the rotation of the steering handle shaft (1), connects the piston bush (4) at its tip to the shaft (3a) on which the rack (3a) is formed. 5) and are designed to move forward and backward in unison.

However, (6) is the gear box (2C) of the gear mechanism (2).
) and the cylinder (7), a fixed guide for fixing the cylinder (7), (
8) is a cylinder stay for fixing the cylinder (7) to the vehicle body (not shown); (9) is a cylinder stay for fixing the cylinder (7) to the vehicle body (not shown);
), (10a) and (]Ob) are cylinder ports that communicate with the two chambers (A) and (B), respectively, defined in the cylinder by this piston rod (9), and (11) is the above-mentioned piston rod. This is a hydraulic valve fixing block with one side of the tip side fixed to the piston bush (4) at the tip of the piston rod (9), and the rack of the gear mechanism (2) is inside the bush (12) fixed to the rear end side. (2a)
IIk (5) is slidably inserted, and the bracket M
(5) Annular stopper members (13a) on both sides of the bushing
, (13b) are fitted and fixed. The distance between the stopper members (13a), (+3b) and both end faces of the bushing (12) is set to about 4 to 5 mm in total, and the shaft (5) is inserted between the bushing (12) and the bushing (12) within this gap. - It is provided so as to be movable relative to the piston bush (4) of the body. (14) is II of axis (5) above! ll
The spool valve is arranged on the tip side along line I and fixed to the hydraulic valve fixing block (11), and the protruding end of the spindle (15) protruding toward the shaft (5) side has a spool valve as shown in Fig. 2. As shown, a bottle (16) is provided through the shaft (16) in the radial direction, and the bottle (16) extends from the vertical slit (5a) formed at the tip of the shaft (5) to the horizontal direction carved at the proximal end of the slit. It is designed to fit into the groove (5b) in the direction and be secured thereto.

The spool valve (14) has four boats (+8
a) , (18b) , (18c) , (18d
), these are (18a) an inflow boat for pressure oil from the hydraulic pump P (Fig. 3), (18b) an outflow boat for pressure oil to the oil tank T (Fig. 3), and (18c) is the inflow and outflow boat of pressure oil to the chamber (B) of the cylinder (7), (
18d) respectively constitute inflow and outflow boats for pressure oil into the chamber (8) of the cylinder (7), and the cylindrical portion (18d)
7) has an annular groove (19a) on the inner peripheral surface thereof, as shown in FIG. 3(a).

(19b), (19c), (19d), (
A plurality of grooves (19e) and (19f) are provided at predetermined intervals in the sleeve direction, and these grooves (19b).

(19c) connects to the outflow boat (18b) via passages (20a) and (20b), and groove (19d) connects to passage (20b).
0c) to the inflow/outflow boat (18c) and the groove (1
9e) enters the inflow boat (18) via the passageway (20d).
a) and the groove (19f) communicate with the inflow/outflow port (18d) via the passageway (20e), and the grooves (19e) and (19a) communicate with the bypass passageway (2O
f). Further, the spool valve (14) has annular grooves (21a) and (21b) on the outer peripheral surface of the other spindle (15).

(21c) are formed in a plurality of strips in the axial direction, and a cavity (22) is provided in the axial center of the spindle (15), and this cavity (22) is provided at multiple locations in the circumferential direction on one end side of the spindle (21c). the groove (21b) through the hole (23) drilled in the
Furthermore, holes (24) are drilled at multiple locations in the circumferential direction on the other end side.
These grooves (21b) and holes (24
) and constitutes a bypass passage (25).

Note that (26) is a pressure control valve, and the oil pressure to the cylinder (7) is adjusted at the time when pressure oil is discharged from the hydraulic pump P, that is, before it reaches the spool valve (14). ing.

In the power steering device of the present invention configured as described above, when no steering operation is performed or when the steering load is light, the pressure oil supplied from the hydraulic pump P is as shown in FIG. 3(a). As shown by the arrow, the inflow boat (18a) passes through the passage (20d) and connects to the groove (19e) of the cylindrical portion (17) and the spindle (1).
5), enters the annular passage formed by the groove (21c), and passes from this annular passage through the bypass passage (2Of) to the cylindrical part (17
) grooves (19a), (19b) and spindle (15
) and a groove (21a), from which the oil flows back to the oil tank T via a passage (20a) and an outflow boat (18b).

In addition, when a load is applied during a steering operation in which the shaft (5) shifts to the left, the shaft (5) moves relative to the hydraulic valve fixing block (11) and moves the spindle (15) to the third position.
Push the spindle (15) as shown in Fig. 3(b) and move the spindle (15) from the state shown in Fig. 3(a) to the left by a distance of 1! II ((:I) and performs a switching operation of the spool valve (14). By this switching operation, the groove (21a) of the spindle (15) and the cylindrical portion (17)
communication with the groove (19b) is cut off, and the spindle (1
The groove (21b) of 5) is the groove (19b) of the cylindrical part (17).
, (19c), and the groove (21c) is the groove (19d) of the cylindrical part (17), (19e), and the hole (24) is the cylindrical part (17).
The pressure oil from the hydraulic pump P passes through the groove (19e) from the passage (20d) to the spindle (15), as shown by the arrow in FIG. 3(b).
passes through the groove (21c) and enters the groove (19d), and from this groove (19d) passes through the passage (20c) to the inflow/outflow port (
18c) to the cylinder (7) boat (Job)
is supplied into the chamber (B). On the other hand, when the cylinder (7) operates and its piston rod (9) extends in the direction of the load applied from the shaft (5), the chamber (A) of the cylinder (7)
The oil inside is discharged from the boat (]Oa), and the oil is discharged from the boat (]Oa).
(18d) through the passage (20e) to the groove (19f)
The cylinder enters the groove (19f), passes through the hole (24) of the spindle (15), passes through the bypass passage (25), passes from the hole (23) on the tip side through the groove (21b), and communicates with this. The grooves (19b) and (19c) of part (I7) are reached, and from these grooves (19b) and (19c), the outflow boat (18
It flows back to the oil tank T via b). And the hydraulic valve fixing block (1) integrated with the piston rod (9).
1) is the axis (5) in the direction (leftward) that reduces the steering load.
) to return the spool valve (14) to its non-steering operation state (FIG. 3(a)).

Additionally, if a load is applied during a steering operation in which the shaft (5) shifts to the right, the shaft (5) moves relative to the hydraulic valve fixing block (11) and moves the spindle (15) to the third position.
The spindle (15) is moved from the state shown in FIG. 3(a) by a distance Ill (C2) to the right with respect to the cylindrical portion (17), and the spool valve (14) is pulled as shown in FIG. Perform the switching operation. With this switching operation,
Communication between the groove (19a) of the cylindrical portion (17) and the groove (21a) of the spindle (15) is cut off, and the groove (19a) of the spindle (15) is cut off.
) groove (21b) is the groove (19c) of the cylindrical part (17),
(19d) and the groove (21c) is the groove (
19e) and (19f), respectively, and the pressure oil from the hydraulic pump P flows as shown by the arrow in FIG. 3(c).
Pass through the groove (19e) from the passage (20d) to the spindle (
It passes through the groove (21c) of the cylinder (7) and enters the groove (19f), and from this groove (19f) it passes through the passage (20e) and the inflow/outflow boat (18d), and then the boat (19f) of the cylinder (7).
0a) into the chamber (A). On the other hand, the cylinder (
7) is working and its piston rod (9) is 11! [
When the cylinder (7) contracts in the direction of the load applied from (5), the cylinder (7
) is discharged from the boat (10b), passes through the passage (20G) from the inflow/outflow boat (18c), and flows into the groove (
19d) and from this groove (19d) spindle (
15) passes through the groove (21b) and reaches the groove (19c),
From this groove (19c), the oil flows back to the oil tank T via the passage (20b) and the outflow boat (18b). The hydraulic valve fixing block (11), which is integrated with the piston rod (9), is mounted in the direction that reduces the steering load (to the right).
The spool valve (1) moves relative to the shaft (5).
4) returns to the state during non-steering operation (FIG. 3(a)).

Note that the deviation m(C+ +C2) of the spindle (15) is
) are each of the aforementioned stopper members (13a) (13b)
Needless to say, it is within the range of the total gap (4 to 5 mm) between the bushing (12) and the bushing (12).

FIGS. 4(a), (b), and (c) show other embodiments of the present invention. In this embodiment, wide arcuate grooves (27a), (27b), and (27c) are formed on the circumferential surface of the spindle (15) of the spool valve (14), so that when no steering load is applied, the hydraulic Pressure oil from the pump P flows into the arcuate grooves (27b), (27a) of the spindle (15) and the grooves (19e), (19d) of the cylindrical portion (17), as shown by the arrows in FIG. 4(a).

(19c) and the meandering passage between the arcuate groove (27b) of the spindle (15), (27c) and the groove (19f) of the cylindrical portion (17). A hole (24) similar to that described above is provided protruding from the arcuate groove (27c).
”) and a second passage leading to the bypass passage (25), the oil flows back from the outflow boat (18b) to the oil tank T, thereby eliminating the need for the bypass passage on the cylindrical part (17) side. is different from that of the previous embodiment.

In this embodiment, the spool valve (14) can be made smaller, and the deflections ff1 (C3) and (C4) of the spindle (15) shown in FIGS. 4(b) and (C) can be shortened. This has the advantage of improving responsiveness.

Note that the flow behavior of the pressure oil indicated by the arrows in Fig. 4(b) and (C) is basically the same as that shown in Fig. 3(b) and (c), so the explanation thereof will be omitted. do.

As described above, in the power steering device of the present invention, the rack shaft (5) of the gear mechanism (2) and the piston rod (9) of the steering booster mechanism (3) are integrally connected, and these Because they are configured to operate in the same direction, even if some abnormality occurs in the steering hydraulic system and it becomes locked,
By cutting off the oil supply path to the cylinder (7) and draining the oil from the cylinder, the locked state can be released, and manual steering operations can also be easily performed.

(Effects of the Invention) As described above, according to the present invention, the valve mechanism is operated by the linear motion part of the gear mechanism, and
This linear motion part and the piston rod of the cylinder controlled by the above-mentioned valve mechanism are configured to move integrally in the same direction, making it possible to perform delicate switching operations of the valve mechanism, resulting in good responsiveness and steering control. When there is an abnormality in the oil pressure system, the effect is that manual steering operations can be easily performed by simply draining the oil in the cylinder.

[Brief explanation of the drawing]

FIG. 1 is a front view showing the overall configuration of the power steering device of the present invention, FIG. 2 is a perspective view showing the main part of the power steering device of the present invention, and FIG.
a), (b), and (C) all show an example of the valve mechanism; Fig. 3 (a) is a sectional view showing its non-operating state, and Fig. 3 (b) and (C) are its sectional views. Cross-sectional views showing the operating states, Fig. 4 (a), (b), (C
) all show other examples of the valve mechanism, and are views corresponding to FIGS. 3(a), 3(b), and 3(c), respectively. (1) --- Handle shaft, (2) --- Gear mechanism, (
2a) - Rack (linear motion part), (2b)...
Pinion, (7)... Cylinder, (9) -...
・Piston rod, (+1)--Hydraulic valve fixing block, (14)--
・Spool valve (valve mechanism), P...hydraulic pump. In each figure, the same reference numerals indicate the same or corresponding parts.

Claims (3)

[Claims] (1) A gear mechanism that converts the rotational motion of the handle shaft into linear motion, a cylinder arranged in the same direction as the movement direction of the linear motion part of this gear mechanism and fixed to the vehicle body, and a piston rod of this cylinder. a hydraulic valve fixing block that is fixed to the side and slidably supports the linear motion section; A power steering device comprising: a valve mechanism that extends and contracts a piston rod of the piston rod in the same direction as the movement direction of the linear motion section. (2) The power steering device according to claim 1, wherein the gear mechanism is composed of a rack and a pinion. (3) The power steering device according to claim 2, wherein the valve mechanism comprises a spool valve whose switching is controlled by the rack shaft.