JPS60226359A - Power steering device in industrial vehicles - Google Patents

Abstract

PURPOSE:To secure a motor-operated power steering device, by using an electric motor for a power source of a booster. CONSTITUTION:When a steering main shaft is operated in rotation clockwise, this turning force is transmitted to a driven shaft 14 from a driving shaft via an elastic body 18. At that time, with elastic deformation in the elastic body 18, a driving plate 9 turns a limit switch R1 for right steering detection use at the first set, to ON operation whereby a motor shaft 11 is rotated clockwise. And, in the case where steering load is large enough, deformation in the elastic body 18 is also large so that another limit switch R2 at the second set is also operated. If so, the electric motor is energized with current through a high torque circuit. That is to say, the electric motor outputs torque by stages in a manner conformable to the steering load.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a power smearing (hereinafter simply abbreviated as PS) device installed in an industrial vehicle such as a forklift or a shovel loader.

Conventional PS systems for vehicles are known to most commonly use hydraulic pressure as a power source. In addition to requiring a considerable amount of space for routing the piping, there is a risk of oil leakage, and the structure is complicated and costs are high. In particular, in the case of a type of PS device called hydrostatic steering, there is no mechanical connection between the steering wheel side and the tire side, so oil leakage may cause the relative position of the steering wheel and tire to shift. ,
There were problems such as damage to the piping, which caused the aircraft to become unable to steer.

OBJECTS OF THE INVENTION An object of the present invention is to provide an electric PS device that uses an electric motor as a power source for a booster, thereby eliminating the problems of the conventional hydraulic PS devices described above.

Structure of the Invention The present invention includes an electric motor disposed between a steering main shaft V-foot and an output shaft, and one end of the electric shaft of the electric motor connected to an end of the steering main shaft 1 shift with an elastically deformable elastic member. The other end of the electric shaft is connected to the output shaft through a gear train, and the connecting part between the steering main shaft and the electric shaft is connected to the electric motor by detecting the elastic deformation of the elastic body. A detector is provided to output an actuation signal, and the electric motor is actuated in response to rotation of the steering wheel, thereby reducing the steering force.

Example 1 Example 1 of the present invention will be specifically described below with reference to FIGS. 1 to 4.

The electric PS device of the present invention is implemented, for example, in a reach-type forklift with one steering wheel, and 1 in FIG. 1 is a steering wheel rotatably attached to a vehicle body frame (not shown). A main shaft is shown, and a switch box 2, an electric motor 3, and a gear box 4 are disposed below the steering main shaft 1 in this order from above, and these are fixed to the vehicle body frame via a bracket 5. A drive shaft 7 housed in the switch box 2 and rotatably supported at its upper end by a bearing 6 has an upper end connected to the steering main shaft 1 via a universal joint 8, and a lower end. is equipped with two drive plates 9 symmetrically across its axis.

The electric shaft 11 of the electric motor 3, on which the armature core coil 10 is wound, is rotatably supported by the switch box 2 and the gear box 4 via bearings 12 at the upper and lower parts. The upper end of the electric shaft 11 is inserted into the switch box 2, and the upper end of the electric shaft 11 is fitted concentrically through a bushing 13 so that it can rotate relative to the drive shaft 7. A boss portion of the driven shaft 14 is fitted on the lower side and is fixed via a key 15. The driven shaft 14 is formed into a substantially bottomed cylindrical shape, and a bifurcated driven plate 17 is formed symmetrically between the outer ring portion 16 and the boss portion with its axis in between. . The drive plate 9 is inserted into the bifurcated space of the driven plate 17, and an elastic body 18 made of rubber or synthetic resin is interposed between both plates 9.17 with a predetermined preload applied thereto. ing. Rinawachi,
The drive shaft 7 and the driven shaft 11 are connected via an elastic body 18.

Further, the driven plate 17 includes limit switches R1 and R2 for detecting right steering and a limit switch L for detecting left steering.
1. L2 and L2 are arranged symmetrically. That is, as shown in FIG. 2, each set of limit switches R1, L
R2, L2 are mounted on the driven plate 17 so as to face each other with the driving plate 9 in between, and the coarse limit switches R1, Ll have their actuators 19 separated from the driving plate 9 by a small gap S1. The second coarse limit switches R2 and L2 are set so that their actuators 20 face the drive plate 9 with a gap S2 larger than that in the case of the second coarse limit switch. Therefore, - coarse and second coarse limit switches R1, Ll and R2
, L2 are turned on in stages according to the steering force (steering load), as shown in the graph of FIG. That is, FIG. 4 shows the relationship between the steering force, the elastic deformation of the elastic body 18 corresponding to the steering force (relative displacement between the driving plate and the driven plate 17), and the activation timing of the limit switch. , - The coarse limit switches R1 and Ll are turned on first.

Further, a power supply ring 21 is attached to the outer peripheral surface of the outer ring portion 16 of the driven shaft 14 in correspondence with each limit switch, and a power supply terminal 22 corresponding to each power supply ring 21 is attached to the switch box 2. There is. The upper and lower ends of the motor yoke 24 equipped with the field coil 23 are fixed to the switch box 2 and the gear box 4, and a brush holder 26 for holding the brush 25 is attached to the motor yoke 24.

On the other hand, the electric shaft 11 inserted into the gear box 4
A pinion 27 is fixed to the lower end of the
The pinion 27 is meshed with an internal gear 30 fixed to the upper end of the output shaft 29. The output shaft 29 is rotatably supported by a bearing 31, and has a sprocket wheel 32 at its lower end.
is fixed to the sprocket wheel 32, and a steering chain 33 for driving a tire-side steering wheel (not shown) is hung from the sprocket wheel 32.

FIG. 3 shows an electric circuit for controlling an electric motor, and the rotation direction of the electric motor 3 is controlled by changing the direction of energization to the field coil 23.
The current direction is the contact MR of the electromagnetic contactor MR for clockwise rotation.
It is determined by which contact point MLa of the electromagnetic contactor ML for counterclockwise rotation is brought into contact with the power supply side terminal. The field coil 23 is energized by a low torque circuit 34 including a resistor RE or a high torque circuit 3 not including a resistor.
The low torque circuit 34 is connected to the coarse limit switch R.
1, the first and second relays MQ connected in series to Ll
1. The first regular contact points MaIal and MO2a1 of MO2 are installed in parallel, and the high torque circuit 35 has third and fourth limit switches connected in series to the second coarse limit switches R2 and L2.
Relay Mo3. Mo2 first normally open contact MQ3a1゜M
q4a1 is installed in parallel. Further, the electromagnetic contactor MR for clockwise rotation includes first and second relays MQ1. M
The second constant contact point MG1a2゜Mq3a2 of Cl3 is installed in parallel, and the second and fourth relays M(]2゜1'14f7) are installed in the electromagnetic contactor ML for counterclockwise rotation.
(12a2.MO4a2 are installed in parallel.KEY is a key switch, and B is a battery.

This embodiment is constructed as described above, and its operation will be explained below.

Now, when the steering main shaft 1 is rotated clockwise, this rotational force is transmitted from the drive shaft 7 to the driven shaft 14 via the elastic body 18, but due to the elastic deformation of the elastic body 18 due to the steering load. Since the drive plate 9 of the drive shaft 7 turns on the limit switch R1 for detecting rough right steering, the first relay M (Jl) is energized and its normally open contacts Mg1a1.M (71a2) are turned on. Therefore, in order to excite the electromagnetic contactor MR for clockwise rotation and bring it into contact with its contact MRaeRa side terminal, the field coil 23 of the electric motor 3 is energized through the low torque circuit 34 including the resistor RE, and the electric shaft 11 is rotated to the right. This rotation is transmitted to the output shaft 29 via the pinion 27 and internal gear 30, and the tire is thereby steered via the steering chain 33.

Furthermore, when the steering load is large, the deformation of the elastic body 18 is correspondingly large, so that not only the -coarse limit switch R1 but also the second coarse limit switch R2 are turned on. Therefore, in this case, the third relay Mg3 is also energized and its normally open contacts MO3a1. Mg5a2 O
N, the high torque circuit 2 in which the field coil 23 of the electric motor 3 is energized does not include the resistor RE! As a result, the current value becomes large and high torque is generated. In other words, the electric motor 3 outputs one herk in stages in response to the steering load, thereby enabling smooth steering.

Note that the counterclockwise rotation operation is a reverse operation of the clockwise rotation described above, and its explanation will be omitted.

Embodiment 2 In Embodiment 2 shown in FIG. 5, the relative rotation between the drive plate 9 and the driven plate 17 is limited by a stopper portion 9a formed on the drive relative. In this case, if the distance S between the stopper portion 9a and the driven plate 17 is set to be slightly larger than the clearance S2 between the actuator 20 of the second coarse limit switch R2, 12 and the driven plate 17, the limit switch ° This is effective in protecting R2 and L2.

Embodiment 3 Embodiment 3 shown in FIG. 6 is a modified example of the gear type reduction section, and as shown in the figure, the electric shaft 11 has a
A ball screw 37 is connected to the ball 3 through the ball 6.
A sector shaft 41 as an output shaft is attached to the rack 40 of the ball nut 39 fitted through the shaft 8.
A sector gear 42, which is fixed to the main body, is engaged with the sector gear 42. Therefore, this embodiment is effective for a drag link type steering device when there are two steered wheels.

It should be noted that the present invention is not limited to the above-described illustrated embodiment; for example, the limit switch for steering detection may be replaced with a reed switch or other switch. Furthermore, the output control of the electric motor 3 is not limited to two stages;
If it increases further, smoother steering becomes possible. Furthermore, if the circuit is constructed using diodes as shown in FIG. 7, the number of relay contacts can be significantly reduced.

Effects of the Invention As described above, the present invention uses an electric motor to
Since it is configured as an S device, it is possible to solve the problems with hydraulic PS devices, such as the difficulty in turning the piping due to space constraints and the risk of oil leakage. Of course, especially since the electric motor is assembled between the steering main shaft and the output shaft, there is an advantage that the structure can be made extremely compact. In addition, since the electric shaft and the steering main shaft are connected through an elastic body, and the elastic body is interposed with a preload, it is possible to prevent vibration-induced chittering. It is effective in
Furthermore, since the steering main shaft is mechanically connected to the tires, safety is guaranteed even if the electric motor, which is the booster, fails.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of the PS device of Example 1 of the present invention, and FIG.
The figure is a sectional view taken along the line ■-■ in Figure 1, Figure 3 is a control circuit diagram of the electric motor, Figure 4 is a graph showing the activation timing of the limit switch, and Figure 5 is a plan view showing Embodiment 2. , 6th
The figure is a longitudinal sectional view showing the third embodiment, and FIG. 7 is a control circuit diagram corresponding to FIG. 3, in which the circuit is constructed using diodes. 1... Sdering main shaft 2... Switch box 3... Electric motor 4... Gear box 7... Drive shaft 11... Electric shaft 14... Driven wheel 18... Elastic body 29... Output shirt 1 to 34... Low torque circuit 35... High torque circuit R1, R2, Ll, L2... Limit switch Applicant Toyota Auto Tan Manufacturing Co., Ltd. Agent Patent attorney Oka 1) Hidehiko

Claims (3)

[Claims] (1) An electric motor is disposed between the steering main shaft and the output shaft, one end of the electric shaft of the electric motor is connected to the end of the steering main shaft through an elastic body that can be elastically deformed, and the electric motor is connected to the steering main shaft. The other end of the shaft is connected to the output shaft via a gear train, and a detector is provided at the connection between the steering main shaft and the electric shaft to detect elastic deformation of the elastic body and output an operating signal to the electric motor. A power steering device for an industrial vehicle, characterized by being provided with. (2) A patent claim characterized in that the detector is configured with a plurality of switches that operate in stages according to the amount of deformation of the elastic body, and the torque of the electric motor is increased according to the steering load. A power steering device for an industrial vehicle according to item 1. (3) The above-mentioned steering wheel main shift] - and electric! II
A power steering device for an industrial vehicle according to claim 1 or 2, wherein the elastic body interposed between the shaft and the elastic body is assembled with a predetermined preload applied thereto.