JPS6112469A - Steering force control device in power steering unit - Google Patents

Abstract

PURPOSE:To simplify the arrangement of a power steering unit and to aim at reducing the cost of the power steering unit, by forming, in a reaction mechanism in the power steering unit, two pressure chambers for applying fluid pressure to the front and rear of a movable piston, and by communicating both chambers with sections upstream and downstream of a control restrictor valve. CONSTITUTION:A power steering unit 10 has a pinion shaft 21 to which steering force is transmitted from an input shaft 23 through a torsion bar 24, in a housing body 11, and a servo-valve 30 is disposed in a hole in a valve housing 12 within the housing body 11. Further, a reaction mechanism 50 is disposed between the rotary valve member 31 of the servo-valve 30 and the pinion shaft 21, and has a movable piston 51 and a ball 52 as main component members. In this arrangement first and second reaction chambers 54, 55 are defined between the movable piston 51 and the pinion shaft 21 as well as the input shaft 23. Further, these reaction chambers 54, 55 are communicated with sections upstream and downstream of a control restrictor valve 79 disposed in a supply passage 72 for the servo-valve 30, through introduction passages 80, 81.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention is directed to a power steering system that is provided with a reaction force mechanism and allows the driver to sense the optimum steering force according to various driving conditions such as the traveling speed of the vehicle. The present invention relates to a steering force control device.

<Prior Art> Generally, a power steering device equipped with a reaction force mechanism requires a fluid supply source for supplying pressure fluid to the pressure chamber of the reaction force mechanism.

Conventionally, the fluid supply sources for this reaction force chamber include: (1) supplying pressure fluid from a steering gear pump to a servo valve; (1) branching a part of the passage on the road side; and supplying pressure fluid to the reaction force chamber via this branch passage; Fluid pressure is introduced into the system, allowing the driver to sense a certain steering reaction force.

However, in the conventional device, in order to generate fluid pressure in the reaction force chamber according to the vehicle speed, a control valve for reaction force control is inserted in the branch passage, and the fluid supplied to the reaction force chamber is In order to prevent the fluid pressure of the servo valve from fluctuating as the servo valve is steered, a switching valve must be inserted to fluidically separate the servo valve and the reaction chamber, which complicates the circuit configuration and increases costs. It becomes a factor.

<Object of the Invention> The present invention has been made in order to solve such conventional problems, and its purpose is to achieve optimal steering force control with a simple and low-cost device i'/. It is to do so.

<Structure of the Invention> In order to achieve the above object, the present invention has a first method that applies fluid pressure to the reaction force mechanism before and after a movable piston that engages with the input shaft. The structure is characterized in that a second reaction force chamber is provided and the first and second reaction force chambers are communicated with the upstream side and the downstream side of the control throttle inserted on the supply path of the servo valve, respectively. It is.

<Example> Embodiments of the present invention will be described below based on the drawings.

As shown in FIG. 1, the present invention includes a power steering device 10, a fluid supply circuit 70 that supplies fluid to a servo valve 30 and a reaction force mechanism 50 incorporated in the power steering device 10, and a power cylinder. Consists of 90.

First, the configuration of the power steering device 10 will be described. The power steering device 10 includes a housing body 11 and a valve housing 12 fixed to the housing body 11. A pinion shaft 21 (
The output shaft (output shaft) is rotatably supported, and each pinion shaft 21 has a rank shaft 22 that can slide in a direction crossing the pinion shaft 21.
The rack teeth 22a are in mesh with each other. This rack shaft No. 22; 1 is connected to the piston 91 of the power cylinder 90,
Its ends are connected to steering wheels via the required steering linkage.

The servo valve 30 housed in the large circle of the valve housing 12 is
The main components are a rotary valve member 31 formed integrally with the input shaft 23 as a steering shaft, and a sleeve valve member 32 fitted to the outer periphery of the rotary valve member 31 concentrically and rotatably relative to each other.

The rotary valve member 31 is flexibly connected to the pinion shaft 21 via a torsion bar 24 which is integrally connected to the input shaft 23 and whose other end is connected to the pinion shaft 21 .

Further, as is well known, a plurality of lands extending in the axial direction are formed at equal intervals on the outer periphery of the rotary valve member 31, and similarly, a plurality of lands extending in the axial direction are formed on the inner periphery of the sleeve valve member 32. A plurality of lands and grooves are formed at equal intervals. Therefore, when the servo valve 30 is in the middle 1'f state, the pressure fluid supplied from the supply boat 35 is evenly distributed to the grooves on both sides of the land part, and the discharged fluid is discharged from the steering shaft 23 and the 1-john. a communication path 25 between the bars 24;
Steering shaft 24 &:: Il'J 13E sat1. 1irll1839, low fE chamber 38 (IJ
It is discharged to the first boat 36. In this case, the redistribution board L3
3 and 34 are at the same pressure in the low mode, and the power cylinder 90 is not operated.

When the servo valve is displaced from the middle) °f state, pressure fluid is supplied from one groove to the power cylinder 90 via the distribution boat 33, and fluid discharged from the power cylinder 90 is transferred from the distribution boat 34 to the other groove. After applying the fluid to
Furthermore, it is discharged into the discharge boat 36 via the communication passage 25° 39 and the low pressure chamber 38.

The reaction force mechanism 50 provided between the rotary valve member 31 and the pinion shaft 21 includes a movable piston 51 and a ball 5.
2 is the main component, and this movable piston 51 is slidable in the inner hole 21a of the pinion shaft 21 and has a pin 53.
The first and second reaction force chambers 54 and 55 are fitted between the pinion shaft 21 and the input shaft 23, respectively.
is formed. This first reaction force chamber 54 has an introduction boat 5
Pressure fluid is introduced into the second reaction chamber 55 from the introduction boat 57 through the communication path 59, and the pressure fluid is introduced into the second reaction chamber 55 from the introduction boat 57 through the communication path 59. .5
The movable piston 51 is made to slide with a differential pressure of 5.5 mm. Further, the ball 52 is connected to the movable piston 51 and the flange portion 59 of the input shaft 23, as shown in FIG.
They are inserted at intervals in the circumferential direction between them, and are in contact with the conical hole 51a formed in the movable piston 51 and the conical hole 23a formed in the input shaft 23, respectively. This contact pressure varies depending on the differential pressure acting on the movable piston 51, and is adapted to apply an appropriate operational reaction force when steering the input shaft 23. Note that 60 is a wave-shaped spring that applies repulsive force to the movable piston 51 in the direction of the input shaft 23 .

- The power fluid supply circuit 70 includes a rudder 1' (M device pump 71 (1Mi) driven by an automobile engine, and controls the flow rate in a supply passage 72 connecting (1) this bomb shift 1 and the supply boat 35). A valve 73 is inserted.The flow rate control valve 73 is controlled by the valve chamber 75 due to the above-mentioned differential pressure of the fixed throttle 74.
The opening of the bypass passage 77 is adjusted by sliding the spool 76 in the axial direction, thereby bypassing the excess flow to the bypass passage 77, thereby keeping the supply flow rate to the power steering device 10 constant. to control.

Furthermore, a control throttle 79 is inserted in the supply passage 72 in series with the flow control valve 73, and a pressure difference ΔP is generated between the control throttle 79 and the fixed throttle 74 of the flow control valve 73. . The pressure on the upstream side of the control throttle 79 and the flow rate control valve 73 is introduced into the first reaction chamber 54 via the introduction passage 80 and the introduction boat 56, and the pressure on the downstream side is introduced into the first reaction force chamber 54 through the introduction passage 81 and the introduction boat 57. It is designed to be introduced into the second reaction force chamber 55 via.

At this time, the differential pressure ΔP is not influenced by the steering of the servo valve 30 as shown in FIG.
41 shows changes in differential pressure due to both the control aperture 79 and the fixed aperture 74. Therefore, the movable piston 51 slides in accordance with this differential pressure ΔP, and applies a steering reaction force to the input shaft 23 that is proportional to the engine speed.

Note that 82 is a discharge passage for discharging the discharged fluid from the servo valve 30 to the tank T.

Next, control of steering force in the power steering system having the above configuration will be explained.

At the same time as starting the engine of the hairdresser, the pump 71 supplies pressurized fluid to the servo valve 30 from the supply 1ffl line 72 via the control throttle 79, the flow rate control valve 73, and the supply boat 35. When the automobile engine rotates at a low speed (during low-speed running), the rotation of the pump 71 is also low, and as shown in FIG. 3, a large differential pressure ΔP is not generated across the control throttle 79 and the fixed throttle 74. Therefore, the contact pressure of the ball 52 with respect to the input shaft 23 is small, and a small steering force creates an opposing burr between the pinion shaft 21 and the input shaft 23, causing the servo valve 30 to operate.
The steering wheel can be operated easily with the assistance of the power cylinder 90.

However, when the engine speed increases (il'li i
In the running state), the rotation of the pump 71 increases and its discharge flow rate increases, generating a large pressure difference ΔP before and after the control throttle 79 and the fixed throttle 74, as shown in FIG. difference j
The ball 5 relative to the input shaft 23 is caused by the emission 11 of 1ΔP.
The contact pressure of the power cylinder 90 increases, and unless a large operating force is applied, the pinion shaft 21 and the input shaft 23 will no longer face each other, and the power assist of the power cylinder 90 will not occur until the relative rotation of the servo valve 30 occurs. I won't be able to work anymore. Therefore, the driver can sense this change in steering force as a steering reaction force, and the stability of steering can be improved.

In the above embodiment, the inner hole 21a is formed in the axial direction of the pinion shaft 21, and the movable piston 51 is moved in the axial direction within this inner hole 21a to generate the steering reaction force, but the present invention is not limited to this. Instead, as shown in FIGS. 4 and 5, a sliding hole 12 is formed in the radial direction of the pinion shaft 21.
1a may be formed, and each movable piston 15 may be slid in the radial direction within the sliding hole 121a. In this case, the first
, second reaction force chambers 154, 155 are formed, and a control aperture 79 and a fixed aperture 7 are formed in the first and second reaction force chambers 1.54, 155.
By introducing the longitudinal pressure of 4, it is possible to generate a steering reaction force proportional to the engine rotational speed, as in the previous embodiment.

<Effects of the Invention> As described in detail above, the present invention provides a first method for applying fluid pressure to the reaction force mechanism before and after the movable piston that engages with the input shaft. A second reaction force chamber is provided, and this first reaction force chamber is provided. Since the second reaction chamber is connected to the upstream and downstream sides of the control throttle inserted in the supply passage of the servo valve, the second reaction chamber is connected to the control valve for reaction force control and the servo valve. This eliminates the need for a switching valve that fluidly separates the vehicle from the power chamber, and has the advantage that optimal steering force control can be achieved with a simple and low-cost device.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, and FIG. 1 is a diagram showing a power steering device of the device of the present invention and a fluid supply circuit that supplies pressure fluid to this power steering device, and FIG. 2 is a diagram showing an embodiment of the present invention. n of
-n line sectional view, FIG. 3 is a diagram showing the relationship between engine speed and differential pressure, FIG. 4 is a partial sectional view of a power steering device showing another embodiment of the present invention, and FIG. FIG. 4 is a sectional view taken along line v-v 1g in FIG. 23...Human power shaft, 30...Servo valve, 31...Lower valve member, 32...Sleeve valve member, 50...
Reaction force mechanism, 51,151...Movable piston, 54,1
54... First reaction force chamber, 55.155... Second reaction force chamber, 71... Pump, 79... Control throttle, 90...
Power cylinder time phase applicant Rishi l l'l 11 Iku Co., Ltd. Toyota Motor Corporation

Claims (1)

[Claims] (1) A power rudder that has a servo valve that controls the distribution of pressure fluid from the pump to the power cylinder by manipulating the input shaft to rotate a pair of valve members relative to each other, and a reaction force mechanism that applies a steering reaction force to the input shaft. In the reaction force mechanism, first and second reaction force chambers are provided for applying fluid pressure before and after the movable piston that engages with the input shaft, and the first and second reaction force chambers are connected to the first and second reaction force chambers. A steering force control device for a power steering device, characterized in that the steering force control device is connected to the upstream side and the downstream side of a control throttle inserted on a supply path of a servo valve.