JPS61160361A - Steering force control device of power steering gear - Google Patents

Abstract

PURPOSE:To prevent damage to a steering system and the like by warningly enabling an operator to be sensible of such a condition, when it occurs, as operational resistance beyond a normal sphere of functioning works and steering input exceeds a definite value and further the quantity of twist of a torsion bar is remarkably increased. CONSTITUTION:Under a condition where a turning wheel is not steerable due to its contact with an obstacle, when an operator turns a handle strongly and continues a handle turning motion beyond limits of normal steering motion, quantity of twist of a torsion bar 9 connecting an input shaft 3 and a screw shaft 6 grows larger. Then, a notch groove 31 of a cylindrical elastic body 30 and a projection 32 of the input shaft 3 are brought into a condition of being engaged with each other. In this condition, however, the torsional reaction force of the torsion bar 9 added with torsional reaction force of the cylindrical elastic body 30 is fed back to the handle side through the input shaft 3. Accord ingly, a feeling different from one in a normal condition is given to the driver, who senses it and stops operation of steerage.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a device for limiting steering force in a power steering device for a large vehicle or the like.

(Prior Art) In a power steering system, the steering output is proportional to the magnitude of the steering resistance acting on the turning vehicle and the steering angle.
As the steering resistance increases, the steering output theoretically tends to increase to infinity.

On the other hand, in order to limit the operating range of the power steering device, a suitable stopper has conventionally been generally provided as a steering force limiting device (steering wheel stopper) at the steering limit angle (steering wheel turning limit angle) or wheel turning limit angle. The operating range is until a part of the steering system comes into contact with this stopper, in other words, the steering angle is limited. For this reason,
If the steering operation is restricted at the steering limit, the operator has no choice but to stop inputting to the handle at that position, and at this time the control valve of the power steering device returns to the neutral position. However, the operation of the power steering stops and the steering output is also reduced.

(Problems to be Solved by the Invention) However, with this restriction device, as described above, the steering operation is suddenly restricted at the steering limit, giving the driver a sense of discomfort, resulting in a problem with the steering feel. In addition, within the normal steering range, if steering resistance suddenly increases temporarily due to wheel 111 hitting an obstacle when stationary, the torsion angle of the torsion bar will be adjusted even though the wheels are not actually turning. In addition, the steering input also increases, resulting in an abnormally large steering output.Therefore, in order to cope with such a situation, it was necessary to increase the mechanical strength of each component of the steering system in advance. Even though it is a power steering device, even if it is within the normal steering operation range, the wheel hits an obstacle and it is difficult to turn the wheel by operating the steering wheel. There is no need to provide an output and the mechanical strength of each component to ensure this output, and if this happens, the driver can be made to foresee this and limit the steering output. If so, it is possible to prevent damage to the steering system or reduce weight by eliminating unnecessary material strength.

The present invention was proposed to solve such problems.
It is.

(Means for Solving the Problems) Therefore, the present invention includes a control valve that switches according to the input signal, and selectively supplies pressure oil to the power cylinder connected to the wheel side via the control valve. In the power steering device, a part of the input shaft is inserted into the low pressure passage in the cylindrical screw shaft, and the two are connected by a tone bar to allow for a relative rotation difference. A first engagement means is formed on the other free end of the cylindrical elastic body, which is located on the inner surface of the screw shaft and has one axial end fixed to the screw shaft, and a first retainer is formed with a certain gap in the shaft rotation direction. A second engagement means that can be engaged with the engagement means is provided on the input shaft inserted into the screw shaft, and when the input steering angle of the input shaft reaches a certain level, an elastic reaction is caused to the input shaft by engagement contact between the two. I tried to give it power.

(Effect-) By imparting elastic warpage to the input shaft, the input torque is greater than the normal steering resistance (the operator can sense it in advance to prevent excessive steering, and the driver can prevent damage to the hydraulic system). This avoids the generation of the necessary high pressure, thereby preventing damage to the steering system and making it lighter and smaller.

(Example) The present invention will be explained below with reference to Examples.

To describe the embodiment shown in FIGS. 1 to 5, 1 is a sill housing, 2 is a differential mechanism, and 3 is an input shaft connected to a handle (not shown). 4 is a sector gear, which is connected to the pitman arm of the steering wheel (not shown), and is finally connected to the rotation (manpower) of the input shaft 3.
, the first instar of the mountain-white 1st year of the year. Inside the cylinder housing 1 is a piston 5 that meshes with the sector gear 4.
are arranged to define working chambers A and B on both sides.

A cylindrical screw shaft 6 is threadedly engaged with the inner peripheral surface of the piston 5 via a ball screw assembly, and is connected to the input shaft 3 via a torsion bar 9 by a pin 7.8.

As the differential gear mechanism C, an M star gear mechanism is used, and a rotatable disk 10 is sandwiched between the input shaft 3 and the screw shaft 6 on the peripheral surfaces thereof.

Sun gears lla and llb are carved symmetrically, respectively, and a plurality of planet gears 12a and 12b meshing with these are symmetrically arranged on both sides of the disk 10 with pins 13. Each planet gear 12a, 12b similarly corresponds to the ring gear 14.
One ring gear 14a, which is meshed with and rotatably supported by the other ring gears 14b1.
is fixed to the differential end housing 2. The control valve 17 is connected to each boat P of RJ and IT as the spool 16 moves.

1' 1M 1-M2 are connected as appropriate to selectively supply pressure fluid to the working chamber A or B defined within the Schillinghausong 1.

As shown in FIG. 3, the impact shaft 3 loosely inserted into the screw shaft 6 switches the control valve 17 by twisting the torsion bar 9 according to the human force value, but the torsion shaft is set to a constant value. Both sides of the input shaft 3 are cut off at a certain angle to form symmetrical side walls 22a, 22b, and correspondingly, engaging side walls 23a, 23b are also formed on the inner periphery of the screw shaft 6. is formed, and when the relative rotational difference between the two reaches a certain value, the side wall portion 22a (22b) comes into contact with the engaging side wall 23a (23b).

Due to this twisting of the input shaft 3, the side wall portion 22a (
An elastic steering reaction force other than the tone 3 member 9 is applied to the input shaft 3 directly when the input shaft 22&> comes into contact with the engaging side wall 23a (2" 3b), so that the continuous shooter can understand the situation. As is clear from Figs. When the relative rotational difference between the input shaft 3 and the screw shaft 6 reaches a constant value, the input shaft 3 and the screw shaft 6 engage with each other.

That is, a notch groove 31 (first engagement means) is formed at the tip of the cylindrical elastic body 30 into which the torsion bar 9 is inserted, while a protrusion 32 (second engagement means) is formed at the tip of the input shaft 3. and both are connected to the <11II wall portion 22 as described above.
a (22b) is in an engaging relationship with a constant gap in the shaft rotation direction such that both abut against the moe that abuts the engagement side wall 23a (2:(b)), and the amount of twist of the torsion bar 9 is When it reaches a certain level, it engages and adds to the steering reaction force.

However, when the steering wheel is rotated and the input shaft 3 is rotated, the sector gear 4 connected to the steering wheel before turning is in a fixed state due to ground resistance, so the screw shaft 6 is stationary when the piston 5 engages with the sector gear 4. and
One sun gear 11b is fixed similarly to the ring gear 14b. Therefore, the sun gear of input shaft 3
Due to the rotation of the planet gear 12a, the disk 10
Since the other planet gear 12 & connected via the planet gear 12 & cannot revolve, it does not revolve but rotates at that position, rotates the ring gear 14a, and moves the spool 16. The control valve 17 switched in this manner supplies pressurized oil from the hydraulic pump to one of the working chambers A and B defined by the piston 5, and at the same time communicates the other to the low-pressure tank side. In this way, a pressure difference is created between both ends of the piston 5, and at the same time the other end is moved to the low pressure tank side? A pressure difference is created between both ends of the piston 5 as if passing through the piston, and at the same time, the rotational force (steering force) of the input shaft 3 is transmitted to the other screw shaft 6 while twisting the torsion bar 9. Sun gear 11b starts rotating at the same rotational speed as sun gear Ila with a slight phase lag. Therefore, the planet gear 12a, which had been only interlocking with its rotation, rotates and moves in tandem with the other planet gears 12b, and as a result, the ring gear 14a is stopped at that position.6 In other words, the control valve 17 is switched. This state is maintained, and from then on, pressure fluid continues to be supplied into the working chambers A (B) until the input shaft 3 stops.

As the screw shaft 6 rotates, the screw thread 5 that is engaged with the screw shaft 6 moves by an amount proportional to the pitch, but the working chamber A
Alternatively, the above-mentioned pressure oil supplied to B allows this transition operation to be performed smoothly, and the person who is hoisting can rotate the sector gear 4 and turn the steered wheels with extremely little force. While the input shaft 3 is rotating, the piston 5 is moved and follows the pitch by an amount proportional to the pitch.

When input shaft 3 is stopped, sun gear 1 naturally
1a stops, but the other sun gear llb rotates by an amount corresponding to the negative torsion applied to the torsion bar 9 and then stops. For a short time until this stop, the planet gear 12a,
Since the ring gear 12b continues to rotate, the ring gear 141, which has been stopped until now, rotates in the opposite direction and stops at the initial position. In other words, the ring gear 14a is rotated by an amount equivalent to the amount of torsion of the torsion lever 9 applied when the input shaft 3 rotates.
rotates, and the spool 16 also returns to the neutral position accordingly.

However, during such a steering operation, for example, when the steering wheel hits an obstacle and becomes unable to steer, which tends to happen when the vehicle is stationary at a stop, it is difficult to grasp the situation. Unless the driver is able to do so, the driver will try to turn the steering wheel even harder due to increased steering resistance.

As the steering wheel continues to rotate beyond the normal steering range, that is, as the human effort (steering angle) increases, the amount of twist of the torsion bar 9 becomes proportional to this unit human effort value. Therefore, when the amount of torsion increases and the notch groove 31 of the cylindrical elastic body 30 engages with the protrusion 32 of the input shaft 3, in addition to the torsional reaction force of the torsion bar 9,
The notch groove 31 of this cylindrical elastic body 30 and the protrusion 32 of the input shaft 3 engage, and in addition to the torsional reaction force of the torsion bar 9, the reaction force that twists this cylindrical elastic body 30 is also transmitted via the input shaft 3. ) is fed back to the steering wheel side, giving the driver a feeling that is different from normal conditions.

In other words, when there is no need to apply an input beyond the normal range, either the steering wheel is in a steering state that has just exceeded the normal reversing range and is nearing its steering limit, or the steering wheel is in a steering state where the steering limit has just been approached, or due to some other reason. It can be considered that the wheel side is in a state where it cannot be steered, and there is no need to use power to steer the vehicle even in such a state. The necessary high pressure may occur, leading to damage to various components and reduced durability, but it is possible to detect and notify the driver of such a situation as a large input torque compared to normal steering resistance. This allows the driver to avoid such situations.

Also, when the input shaft 3 is rotated in the opposite direction to the above explanation (rotating counterclockwise in FIGS. 3 and 5), or when the steering wheel approaches its steering limit, Similarly to the above, by applying an elastic reaction force above a predetermined rotation angle of the input shaft, it is possible to make the driver sense a larger input torque than normal steering resistance, and this can be used as a warning signal. I can do it.

(Effects of the Invention) As explained above, according to the present invention, when the steering input exceeds a certain value and the torsion plate of the torsion bar □ increases significantly, that is, the steering resistance exceeds the normal operating range. When the steering system and hydraulic pressure Damage to the system can be avoided, and therefore there is no need to provide unnecessary material strength to each component, so the overall weight and size can be reduced.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of the present invention, Fig. 2 is a sectional view taken along line l-1 in Fig. 1, Fig. 3 is a sectional view taken along line ■-■ in Fig. 1, and Fig. 4 is a sectional view taken along line 1-1 in Fig.
FIG. 5 is an enlarged sectional view of section C in the figure, and FIG. 5 is a sectional view taken along line I-1 in FIG. 3...Input shaft, 5...Piston, 6...
...Screw shaft, 9...Torsion bar, 1
7... Control valve, 21... High pressure passage, 22a, 2
2b...Side wall portion, 23a, 23b...Engagement side wall, 3
0...Cylindrical elastic body, 31...Notch groove, 32...Protrusion. Patent applicant Kayaba Kogyo Co., Ltd. Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] A power steering device is equipped with a control valve that switches according to the input rotation, and selectively supplies pressure oil to a power cylinder connected to the wheel side via the control valve. A part of the input shaft is inserted into the low pressure passage inside the screw shaft, and the two are connected with a torsion bar to allow for a relative rotation difference, while one axial end is fixed to the screw shaft on the inner surface of the screw shaft. A first engaging means is formed at the other free end of the cylindrical elastic body, and a second engaging means capable of engaging with the first engaging means is connected to the screw shaft with a certain gap in the axial rotation direction. A steering force limiting device for a power steering device, which is provided on an input shaft inserted into the input shaft, and applies an elastic reaction force to the input shaft by engaging and abutting the two when the input steering angle of the input shaft reaches a certain value.