JP2599698Y2 - Power steering device - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power steering device for generating a steering assist force by directly using an engine output of a vehicle.

[0002]

2. Description of the Related Art A mechanism for transmitting an output of a hydraulic actuator operated by pressure oil sent from a pump to a steering force transmission mechanism as a steering assist force, a control valve for controlling a hydraulic pressure applied to the hydraulic actuator in accordance with a steering resistance, and And a mechanism for transmitting the output of an electric motor to a steering force transmission mechanism as a steering assist force, and an electric power including means for controlling the output of the electric motor in accordance with a detection value of a torque sensor. BACKGROUND ART A steering device has been conventionally used.

[0003]

The conventional power steering apparatus requires a dedicated hydraulic actuator or an electric motor as a source of the steering assist force, and therefore has a complicated structure and is expensive.

An object of the present invention is to provide a power steering device that can solve the above-mentioned problems of the prior art.

[0005]

SUMMARY OF THE INVENTION The present invention provides a torque sensor for detecting a steering torque, a clutch for transmitting an engine output of a vehicle to a steering force transmission mechanism as a steering assist force, and a transmission power by the clutch for the torque sensor. Rack and pinion type power steering having means for controlling according to a detected value
In the ring device, the steering wheel is connected to both ends.
The ball screw shaft is integrated with the
The ball nut is screwed into the ball screw shaft of
The clutch includes a pair of driven-side rotating members and the
Single drive side rotating member driven by engine output
And the driven side rotating members are arranged in the axial direction of the rack bar.
Are arranged in parallel along the
The material is disposed between the driven side rotating members, and each driven side rotating member is
The members are opposite to each other due to the rotation transmitted from the driving side rotating member.
When the steering wheel is steered to the left,
One of the driven-side rotating members transmitted to rotate from the
The nut and the nut can rotate together.
The other driven-side rotating member whose rotation is transmitted from the driven-side rotating member
And the nut are rotatable together.
And

[0006]

According to the structure of the present invention, since the engine output of the vehicle is directly used as the steering assist force, a dedicated steering assist force source is not required. Moreover, when steering right and when steering left
The clutch for changing the direction of the steering assist force is a pair of clutches.
It is composed of a driven side rotating member and a single driving side rotating member,
Screw into the ball screw shaft integrated with the rack bar
Rotation was transmitted from the driving side rotating member.
Steering assist force acts by rotating along with the driven side rotating member
Small, lightweight, simple structure, and low power loss
Reduction and improvement in fuel efficiency can be achieved.

[0007]

2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A power steering apparatus 1 shown in FIG. 2 includes a pinion 4 connected to a steering handle 2 via a handle shaft 3, and a rack bar 5 having a rack meshing with the pinion 4. Ball joints (not shown) at both ends of the rack bar 5.
Steering wheels are connected via tie rods, knuckle arms, and the like, and the steering of the vehicle is performed by rotating the pinion 4 and moving the rack bar 5 by rotating the handle 2. A power transmission mechanism 10 for transmitting the output of the traveling drive engine 6 of the vehicle to the steering force transmission mechanism as a steering assist force, and a control device 11 for controlling the transmission power by the power transmission mechanism 10 in accordance with a detection value of a torque sensor. Are provided.

As shown in FIG. 1, the power transmission mechanism 10 has an electromagnetic friction clutch 13 mounted inside a rack housing 12 that covers the rack bar 5. The electromagnetic friction clutch 13 includes a clutch case 14 fixed to the rack housing 12 and the clutch case 1.
4, a pair of electromagnetic coils 15 and 16, a clutch rotor 17 facing one of the electromagnetic coils 15,
And a clutch rotor 18 facing the other electromagnetic coil 16. Each of the clutch rotors 17 and 18 is fitted to a ball nut 22 rotatably mounted on the clutch case 14 via a bearing 20 via a spline so as to be rotatable with the ball case and relatively movable in the axial direction. A ball screw shaft 24 inserted into the ball nut 22 via a ball 23 is integrated in the middle of the rack bar 5. Bearing 25 is attached to the clutch case 14.
The power take-out shaft 26 of the engine 6 is supported through the shaft, and a friction wheel 27 is attached to an end of the power take-out shaft 26.

As a result, when one electromagnetic coil 15 is excited, as shown in FIG.
The rotation of the power take-out shaft 26 of the engine 6 is transmitted from one clutch rotor 17 to the ball nut 22, and the rotation of the ball nut 22 in one direction causes the rotation of the power take-out shaft 26 to be integrated with the ball screw shaft 24. The steering assist force to the left or right is transmitted to the rack bar 5. Further, when the other electromagnetic coil 16 is excited, FIG.
As shown in FIG.
The rotation of the power take-out shaft 26 of the engine 6 is transmitted from the other clutch rotor 18 to the ball nut 22, and the rotation of the ball nut 22 in the other direction causes the rack bar 5 integrated with the ball screw shaft 24 to rotate.
The steering assist force is transmitted to the other side. A spring for applying an elastic force to urge the clutch rotors 17, 18 in a direction away from the friction wheel 27 may be provided between the clutch rotors 17, 18 and the ball nut 22.

The control device 11 is constituted by a computer, and changes the exciting current applied to each of the electromagnetic coils 15 and 16 of the electromagnetic friction clutch 13 in accordance with the detected steering torque and the detected vehicle speed, thereby changing the electromagnetic current. The power transmitted by the friction clutch 13 is controlled in accordance with the detected steering torque and the detected vehicle speed.

That is, the handle shaft 3 includes an input shaft 3a that rotates together with the steering handle 2, an output shaft 3c that rotates together with the pinion 4, and a torsion bar connecting the input shaft 3a and the output shaft 3c. 3b, and the torsion bar 3b is twisted by a torque acting based on the steering torque. A torque sensor 30 for detecting the torsional torque of the torsion bar 3b is provided. The torque sensor 30 and a vehicle speed sensor 31 for detecting the vehicle speed are connected to the control device 11. As the torque sensor 30, for example, the one disclosed in Japanese Utility Model Laid-Open Publication No. 4-43236 can be used.

The pressing force of the clutch rotors 17 and 18 pressing the friction wheel 27 is P, and the clutch rotors 17 and 1
Assuming that the friction coefficient of the contact surface between the friction clutch 8 and the friction wheel 27 is μ and the average diameter of the contact surface is D, the transmittable torque T of the electromagnetic friction clutch 13 is theoretically T = μPD / 2, and the pressing force thereof P is proportional to the exciting current I applied to each of the electromagnetic coils 15 and 16. Therefore, as shown in FIG. 5, the exciting current I and the transmittable torque T of the electromagnetic friction clutch 13 are determined.
Is proportional to Thereby, as shown in FIG. 6, the engine torque taken out from the engine 6 via the power take-out shaft 26 is shown by a broken line Te, and the transmission torque converted into the steering assisting force acting on the rack bar 5 is shown by a solid line. When Tc as the value of the transmission torque Tc is up to equal to the engine torque Te increases in proportion to the exciting current I, the exciting current I becomes equal to the engine torque Te reaches the I ₁ 6 The transmission torque Tc does not change even if the exciting current I increases. While the transmission torque Tc increases in proportion to the exciting current I, each clutch rotor 1
There is a relative slip between the friction wheels 7, 8 and the friction wheel 27. When the transmission torque Tc reaches a certain value, the clutch rotors 17, 18 and the friction wheel 27 rotate together without relative slip. Its engine torque Te usually is not constant but varies, the excitation current I is smaller than the current value I ₁ in which the transmission torque Tc engine torque decreases than the value Te as indicated by a dashed line reaches a certain value I ₂
Next, the excitation current I of the transmission torque Tc engine torque also increases from the value Te as indicated by the two-dot chain line reaches a certain value becomes a large value I ₃ than the current value I _1. Therefore, by setting the maximum value of the excitation current I of the electromagnetic friction clutch 13 so that the transmission torque Tc does not become larger than the minimum value of the fluctuation range of the engine torque, the transmission torque Tc proportional to the excitation current I is generated. be able to.

As shown in FIG. 7, the control device 11 comprises:
When steering to the left or right, the exciting current I applied to one electromagnetic coil 15 of the electromagnetic friction clutch 13 is increased as the torsional torque Tm of the torsion bar 3b is increased, and the torsional torque Tm is increased when steering to the other left or right. Excitation current I applied to the other electromagnetic coil 16 is increased. In the range where the vehicle speed is low, the rate of increase of the exciting current I with respect to the torsional torque Tm is increased, and in the range where the vehicle speed is high, the rate of increase of the exciting current I with respect to the torsional torque Tm is reduced. As a result, as shown in the control block of FIG. 8, the total steering torque To, which is the sum of the torsional torque Tm and the transmission torque Tc acting on the output shaft 3c of the handle shaft 3, increases as the torsional torque Tm increases. The rate of increase with respect to the torsional torque Tm increases as the speed decreases, and the torsional torque Tm increases as the speed increases.
The rate of increase with respect to is small. Therefore, the rack bar 5
Can be increased as the steering torque increases, and the steering input torque Ti decreases as the steering speed decreases.
Even if the steering torque is small, the steering response can be satisfied by increasing the steering torque, and the steering stability can be satisfied by not increasing the steering input torque Ti as the speed becomes higher unless the steering input torque Ti is increased.

According to the above configuration, since the output of the engine 6 is directly used as the steering assist force, a dedicated steering assist force source is not required, so that the structure can be simplified and the cost can be reduced.

The present invention is not limited to the above embodiment. For example, as shown in FIG. 9, a power transmission mechanism 50 having an electromagnetic powder clutch 53 instead of the electromagnetic friction clutch 13 may be used. That is, the electromagnetic powder clutch 53 includes a clutch case 54 fixed to the rack housing 12, a pair of electromagnetic coils 55 and 56 attached to the clutch case 54, and radially inward of the two electromagnetic coils 55 and 56. Position both electromagnetic coils 5
5 and 56, and a clutch rotor 57 opposed to the clutch rotor 57. The clutch rotor 57 is fitted and fixed to a ball nut 62 rotatably mounted on the clutch case 54 via a bearing 60. The ball nut 62
A ball screw shaft 64 inserted into the rack bar 5 through a ball 63 is integrated with the rack bar 5.
The power take-off shaft 26 of the engine 6 is supported by the clutch case 54 via a bearing 65, and a bevel gear 67 is attached to an end of the power take-out shaft 26. A pair of bevel gears 6 meshing with the bevel gear 67
8, 69 are bearings 70, 7 on the ball nut 62.
1 is supported. The two electromagnetic coils 55, 56 and the clutch rotor 57 are arranged between the two bevel gears 68, 69, and the cylinder 72 located between the one electromagnetic coil 55 and the clutch rotor 57 is integrated with the one bevel gear 68, The other electromagnetic coil 56 and the clutch rotor 5
7 and the other bevel gear 6
9 are integrated. A ring-shaped seal 75 is disposed between the two cylinders 72, 73, and the two cylinders 72, 73
The magnetic powder 80 is housed inside. Other parts are the same as those in the above embodiment, and the same parts are indicated by the same reference numerals.

As a result, when one of the electromagnetic coils 55 is excited, the magnetic powder 80 is solidified between the outer periphery of the end portion 57a of the clutch rotor 57 and the inner periphery of the cylinder 72 by the magnetic flux 90 shown by the broken line in the drawing. The rotation of the power take-out shaft 26 of the engine 6 is transmitted from the one bevel gear 68 to the ball nut 62 via the clutch rotor 57, and the rotation of the ball nut 62 in one direction is performed. Thus, the steering assist force to the left or right is transmitted to the rack bar 5 integrated with the ball screw shaft 64. When the other electromagnetic coil 56 is excited, the magnetic powder 80 is solidified between the outer periphery of the end portion 57b of the clutch rotor 57 and the inner periphery of the cylinder 73 by the magnetic flux 91 shown by a broken line in the figure, and the other cylinder 73 And the clutch rotor 57 are connected, and the power take-out shaft 2 of the engine 6 is connected.
6 rotates from the other bevel gear 69 to the clutch rotor 5.
The steering assist force to the right and left sides is transmitted to the rack bar 5 integrated with the ball screw shaft 64 by the rotation of the ball nut 62 in the other direction.

The transmittable torque T of the electromagnetic powder clutch 53 is, as shown in FIG.
6 can be expressed as a function of the exciting current I applied to one of them. Further, the transmission torque of the electromagnetic powder clutch 53 is hardly affected by the relative rotation speed between input and output, as shown in FIG. Therefore, by controlling the exciting current I, the transmission torque of the electromagnetic powder clutch 53, which is converted into the steering assist force acting on the rack bar 5, can be controlled in the same manner as in the above embodiment.

[0018]

According to the power steering apparatus of the present invention, the engine output can be used as a steering assist force via the clutch , and the clutch can be used as a small steering power.
Type lightweight it is possible to use a structure as simple Runode,
The structure can be simplified and the cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view for explaining the configuration of a power transmission mechanism of a power steering device according to an embodiment of the present invention.

FIG. 2 is a configuration explanatory view of the power steering device according to the embodiment of the present invention;

FIG. 3 is a sectional view for explaining the operation of the power transmission mechanism of the power steering device according to the embodiment of the present invention;

FIG. 4 is a sectional view for explaining the operation of the power transmission mechanism of the power steering device according to the embodiment of the present invention;

FIG. 5 is a diagram showing a relationship between a clutch coil exciting current and a clutch transmittable torque of the power steering device according to the embodiment of the present invention;

FIG. 6 is a diagram showing the relationship between the clutch coil exciting current, the engine torque, and the transmission torque of the power steering device according to the embodiment of the present invention;

FIG. 7 is a diagram showing a relationship between a clutch coil exciting current and a torsional torque of the power steering device according to the embodiment of the present invention;

FIG. 8 is a control block diagram of the power steering device according to the embodiment of the present invention;

FIG. 9 is a cross-sectional view for explaining the configuration of a power transmission mechanism of a power steering device according to a modification of the present invention.

FIG. 10 is a diagram showing a relationship between a clutch coil exciting current and a clutch transmittable torque of an electromagnetic powder clutch according to a modification of the present invention.

FIG. 11 is a diagram showing the relationship between the input / output relative rotation speed of the electromagnetic powder clutch and the clutch transmission torque according to a modification of the present invention.

[Explanation of symbols]

 6 Engine 11 Control device 13 Electromagnetic friction clutch 53 Electromagnetic powder clutch

Claims (1)

(57) [Scope of request for utility model registration] A torque sensor for detecting a steering torque;
La comprising a clutch for transmitting the engine output of the vehicle as a steering assist force to the steering force transmission mechanism, and means for controlling response transmission power by the clutch on the detected value of the torque sensor
In a pinion type power steering device, a ball bar is attached to a rack bar to which steering wheels are connected at both ends.
The screw shaft is integrated, and the ball nut is screwed into the ball screw shaft.
Is, the clutch includes a pair of driven side rotational member thereof, the engine
A single driving-side rotating member that is rotationally driven by the
Having both driven side rotating members along the axial direction of the rack bar.
The driving-side rotating members are arranged in parallel, and the driving-side rotating members are disposed between the driven-side rotating members.
Are each driven side rotational member to the transmission of rotation from the prime mover rotating member
When the steering is performed to the left, the rotation is transmitted from the driving side rotating member.
One of the driven-side rotating members and the nut can rotate together.
When steering to the right, rotation is transmitted from the driving side rotating member.
The other driven side rotating member and the nut are rotated together.
A rack-and-pinion type power steering device, which is made possible .