JPS6234586B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention basically consists of
Patent application filed on January 17, 1983, Japanese Patent Application No. 56-5763 ``Forklift with selectable steering attitude''
This invention is related to Japanese Patent No. 121599 (hereinafter referred to as the previously filed invention), and relates to a device for properly maintaining the turning angle of a driving wheel in a turning position on the spot.

The above-mentioned previously filed invention is a forklift that steers the front two wheels as idle wheels and the rear wheel as a driving wheel, in which a steering mechanism using a hydraulic motor as a drive source is incorporated in each of the left and right idle wheels, and the turning angle of the idle wheels and the driving wheel is determined by a voltage value. By installing a circuit that controls the hydraulic motor by comparing these voltage values, it is possible to take any one of the following three steering positions. It is.

(1) Standard steering position As shown in Figure 1, the turning angles of the left and right idle wheels are both set to zero, and the driving wheels are turned to steer. In this case, the turning angle of the left and right idle wheels always turns in line with the longitudinal direction of the car body, regardless of the turning angle of the driving wheels, and the car body turns in the direction shown by arrow _A1 , similar to the turning position of a general forklift. proceed.

(2) Oblique steering position As shown in Figure 2, the turning angle of the left and right idle wheels is always set to match the turning angle of the driving wheels, and the driving wheels are turned to steer. In this case, the turning angles of the left and right idle wheels follow the turning angles of the driving wheels, and the vehicle body runs diagonally in _{the two} directions of arrow A.

(3) On-the-spot turning position As shown in Figure 3, the turning angles of the right and left idle wheels are set to the optimum on-the-spot turning angles α and β, respectively, and the turning angle of the driving wheels is set to the optimum on-the-spot turning angle γ. and turn the vehicle body on the spot as shown by arrow A ₃ or arrow A ₄ .

By the way, the structure and operation of a reach forklift as an embodiment of the forklift according to the previously applied invention as described above will be explained as follows.

Figure 4 shows the structure around the idler. The idler wheel 1 is pivotally supported by an idler bracket 2, and the turning torque of a hydraulic motor 4 is transmitted via a spur gear 3 fitted to the idler bracket 2 and an intermediate gear 5. The rotated angle is transmitted from the potentiometer spur gear 6 meshing with the spur gear 3 to the control mechanism via the potentiometer 7.

Figure 5 shows the configuration around the driving wheels. The driving wheels 8 are turned by an operator, and turning torque from a hydraulic motor 9 is transmitted via a spur gear 10 . The rotated angle is transmitted to the control mechanism via the potentiometer 12 from the potentiometer spur gear 11 meshing with the spur gear 10.

Fig. 6 shows a hydraulic system diagram of the steering mechanism for the driving wheels and idler wheels. In the figure, P is a pump for the steering mechanism, M _D is a hydraulic motor for driving wheels, M _R is a hydraulic motor for right idle wheels, M _L is a hydraulic motor for left idle wheels, and V _R is a directional control valve for right idle wheels. , S ₁ is V _R
S ₂ is the solenoid for the left direction of V _R , V _L is the left idler directional control valve, S ₃ is the V _L
S4 is a solenoid for the left direction of _VL , and C is a driving wheel turning direction control device.

Figure 7 shows the electrical system diagram of the steering mechanism. In the figure, PB ₁ is a push button switch for standard steering attitude, PB ₂ is a push button switch for oblique steering attitude, PB ₃ is a push button switch for spot turning attitude, S ₁ , S ₂ , S ₃ , _S4 is each solenoid switch explained in Fig. 6 above, P
_R and P _L are the voltage comparison circuit devices for the right and left idle wheels respectively, VR ₁ is the voltage value obtained by the resistance value corresponding to the zero turning angle of the right and left idle wheels, and VR ₂ is the right idle wheel turning angle that is optimal for turning on the spot. VR 3 is the voltage value obtained by the resistance value corresponding to the angle, VR ₃ is the voltage value obtained by the resistance value corresponding to the optimum turning angle for the left idler wheel, VP ₀ is the voltage generated in the driving wheel potentiometer when turning, VP _R is the voltage generated in the right idle wheel potentiometer when turning, and VP _L is the voltage generated in the left idle wheel potentiometer when turning.

In the configuration of the previously filed invention as described above, the respective effects depending on the steering attitude selection will be explained.

(1) In the case of standard steering attitude Press push button switch PB ₁ . This closes relays XN ₂ and XN ₃ , so the voltages VP _R and VP _L generated by the turning of the right and left idle wheels are compared with the voltage VR ₁ when the turning angle of the right and left idle wheels is zero (a) Regarding the right idle wheels When VP _R > VR ₁ , S ₁ turns ON and turns to the right, and when VP _R < VR ₁ , S ₂ turns ON and turns to the left.

(b) For the left idle wheel, if VP _L > VR ₁ , S ₃ will turn on and turn to the right, and if VP _L < VR ₁ , S ₄ will turn on and turn to the left.

That is, both the right and left idlers are controlled to have a turning angle of zero, and the direction of the idlers coincides with the longitudinal direction of the vehicle body. In this case, the voltage generated due to the rotation of the driving wheels
It has nothing to do with VP ₀ .

(2) For diagonal steering mode: Press push button switch PB ₂ . This closes relays XC ₂ and XC ₃ , so compare the voltage VP ₀ generated by the turning of the driving wheel with the voltages VP _R and VP _L generated by the turning of the right and left idlers. (a) For the right idler: When VP _R > VP ₀ , S ₁ turns ON and turns to the right; when VP _R < VP ₀ , S ₂ turns ON and turns to the left.

(b) For the left freewheel, if VP _L > VP ₀ , S ₃ will turn ON and turn to the right; if VP _L < VP ₀ , S ₄ will turn ON and turn to the left.

That is, the turning angles of the left and right idle wheels are always controlled to match the turning angles of the driving wheels. By the way, since the driving wheels are turned in the direction requested by the driver, the vehicle body always runs obliquely in the direction requested by the driver.

(3) When ready to turn on the spot: Press push button switch PB ₃ . As a result, relays XR ₂ and XR ₃ are closed, so the generated voltages V _R and V P _L of the right and left idle wheels are compared with the voltages VR ₂ and VR ₃ at the optimum turning angle on the spot, respectively (a) Right Regarding idle wheels, when V _R > VR ₂ , S ₁ is turned on and turns to the right, and when V _R < VR ₁ , S ₂ is turned on and turns to the left.

(b) For the left idle wheel, if VP _L > VR ₃ , S ₃ will turn ON and turn to the right; if VP _L < VR ₃ , S ₄ will turn ON and turn to the left.

In other words, the right and left idlers are controlled to match the optimum angle for turning on the spot. Regarding the driving wheels, the operator turns the driving wheels to the optimum angle for turning on the spot, and after both the driving wheels and idle wheels are at the optimum angle for turning on the spot, the driver operates the accelerator on the vehicle body. If so, the vehicle will turn on the spot clockwise or counterclockwise depending on the direction of the accelerator.

The above is an overview of the structure and operation of the previously applied invention.

By the way, in the case of the above-mentioned forklift according to the previously applied invention, when the forklift is in a turning position on the spot,
The right and left idlers and driving wheels must each be maintained at a predetermined turning angle. However, hydraulic motors generally suffer from some internal leakage compared to cylinder-type hydraulic actuators, and disturbance torque from the tire road surface tends to disturb the turning angles of idle wheels and driving wheels, causing them to shift from the optimal position for turning. . In order to eliminate such drawbacks and maintain the swing angle of the idler properly, a patent application filed by the same applicant on January 21, 1982,
No. 7475 "Device for holding the swing angle of a forklift idler" (hereinafter referred to as related invention), which electrically detects when the swing angle of the idler reaches a predetermined angle and brakes the swing of the idler. The equipment is described in detail. The outline is as follows.

First, the electrical system shown in FIG. 8 will be explained. This diagram is based on the electrical system diagram shown in Figure 7, with some circuits added.The basic parts are shown using the same symbols as in Figure 7, and the added parts are mainly shown on the right side of the diagram. It is shown. In the additional circuit, X _A is the coil that operates when the solenoid is energized,
D ₁ , D ₂ , D ₃ , D ₄ , and D ₅ are diodes, XR ₄ is a switch that turns on when the driving wheels reach the appropriate turning angle, and PL ₁ , PL ₂ , and PL ₃ are each in the standard steering position. , an appropriate angle indicator lamp for diagonal steering mode and on-the-spot turning mode, and _S5 is a solenoid for operating the idler wheel proper angle holding device. In a circuit like the one above, S ₁ ~
While any of _S4 is energized, the _coil
Since all of S ₁ to _{S 4} are de-energized, coil X _A
is turned off, relay _XA is turned on, and the appropriate angle display lamp PL ₁ , PL ₂ or PL ₃ is displayed for each steering position
lights up, relay XN ₁ is turned on in the standard steering position, switch XR ₄ and relay XR ₁ are turned on in the spot turning position, and solenoid S ₅ for operating the holding device is energized.

As mentioned above, when the solenoid _S5 is energized, the turning angle of the idler wheel can be maintained by a device using an electromagnetic brake, a device using a solenoid valve and a stopper, or a device using a hydraulic cylinder and a stopper. The brake system is activated.

The above is a summary of inventions related to existing applications.

Incidentally, the turning angle of the driving wheels is also disturbed due to internal leakage of the hydraulic motor and disturbing torque from the tire road surface, and when the driving wheels are in the on-the-spot turning position, they tend to deviate from the optimum position. In such a case,
If the turning angle of the driving wheels deviates from the optimal position and the vehicle turns on the spot, problems such as increased lateral tire slippage, shortened tire life, and increased turning radius will occur. do. .
A similar phenomenon occurs when the vehicle body starts turning with the driving wheels not in the optimum position for turning on the spot. Therefore, while the vehicle is turning, the operator must always keep the driving wheels at the optimum angle and, if necessary, turn the steering wheel to correct the turning angle of the driving wheels.

The present invention eliminates the above-mentioned drawbacks, lights up an indicator light indicating that the driving wheels are at the optimum angle when the vehicle body starts turning in the on-the-spot turning position, and at the same time prevents the turning angle from being disturbed during the turn. The object of the present invention is to provide a device that correctly holds the lens at an optimal angle.

Embodiments of the present invention will be described below with reference to the drawings. In FIGS. 9 and 10, members that are the same as or equivalent to those shown in FIGS. 1 to 8 are designated by the same reference numerals.

In FIG. 9, a striker 14 is attached to a spur gear 10 attached to a portion 13 that rotates together with the driving wheel 8.
to fix. On the other hand, a limit switch 16 is attached to the fixed part 15 of the driving wheel drive device, and the striker 1
4 is arranged so that the limit switch 16 is energized. Further, a solenoid valve 17 is attached to the fixed part 15, and its pin 18 is slidably supported by a slide metal bearing 20 fitted into a bracket 19 attached to the fixed part 15.
A fixing hole 20 is drilled in the pin 1, and when the limit switch 16 is energized, the solenoid valve 17 is activated and the pin 1 is energized.
8 slides on the slide metal bearing 20 and is arranged so as to fit into the fixing hole 20. Therefore, when the driving wheel reaches the optimum angle for turning on the spot, the limit switch 16 is energized and the pin 18 of the solenoid valve 17 is fitted into the fixing hole 20, thereby fixing the runout of the turning portion of the driving wheel. and keep the tires at the optimal turning angle.

Figure 10 shows the electrical system diagram. This figure is an electrical system diagram for the device for maintaining the swing angle of the idler wheels shown in FIG. 8, with the circuit necessary for the device for maintaining the swing angle of the driving wheels added to the right side of the figure. In FIG. 10, _XR4 is a contact of the limit switch 14, _S6 is an electromagnetic coil, and SOL1 is a solenoid coil of the electromagnetic valve 17. As mentioned above, when the idler wheel is at the optimum turning angle, X _A is energized, and when the driving wheel reaches the optimum turning angle, the contact point XR ₄ of the limit switch 14 is turned on.
The indicator light PL ₃ on the instrument panel, which indicates the completion of the on-spot turning posture transition, lights up only when the power is applied and both the idler wheels and the driving wheels reach the optimum turning angle. At the same time, the electromagnetic coil _S6 is energized, the solenoid coil SOL1 of the electromagnetic valve 17 is activated, the pin of the electromagnetic valve is inserted into the fixing hole, and the driving wheel is held at the optimum turning angle.

After the vehicle turns, the purpose is to shift to a steering attitude different from the spot turning attitude by pressing the standard steering attitude push button switch PB ₁ or the diagonal steering attitude push button switch PB ₂ . Immediately, the holding device releases its holding position.

As described above, according to the device for maintaining the driving wheel turning angle of a forklift according to the present invention, by lighting the indicator light, both the idler wheels and the driving wheels are adjusted to the optimum turning angle on the spot before the vehicle body starts turning. By confirming that the driving wheel is at the correct angle, and during turning, the pin of the solenoid valve fits into the fixing hole in the rotating part, the driving wheels are held at the optimum turning angle, and the stirring torque from the road surface and the oil of the hydraulic motor are prevented. This has an extremely excellent effect of preventing displacement and slipping of the driving wheels due to leakage or the like.

[Brief explanation of the drawing]

Figures 1 to 7 relate to the already-filed invention "a forklift with selectable steering positions," in which Figure 1 is a plan view showing the standard steering position, and Figure 2 is a plan view showing the oblique steering position. 3 is a plan view showing the on-spot turning position, FIG. 4 is a sectional front view showing the configuration around the idler wheels, FIG. 5 is a sectional front view showing the configuration around the driving wheels, and FIG. 6 is a sectional front view showing the configuration around the driving wheels. FIG. 7 is a hydraulic system diagram of the driving wheel and idler wheel steering mechanism, and FIG. 7 is an electrical system diagram of the driving wheel and idler wheel steering mechanism. FIG. 8 is an electrical system diagram of the related invention "Forklift idler turning angle holding device". 9 and 10 both relate to an embodiment of the present invention; FIG. 9 is a sectional front view showing the structure around the driving wheels, and FIG. 10 is an electrical system diagram. 14... Striker, 16... Limit switch, 17... Solenoid valve, 18... Pin, 20... Fixing hole.

Claims (1)

[Claims] 1 In a configuration in which the front two wheels are used as idle wheels and the rear wheel is used as a driving wheel for steering, each idle wheel is equipped with a steering mechanism using a hydraulic motor as a drive source, and a device is provided for extracting the turning angle of the idle wheel and the driving wheel as a voltage value, Furthermore, in a forklift equipped with a circuit that controls the hydraulic motor by comparing the voltage values depending on the turning angle of the idler wheels and the driving wheels, when taking a turning position on the spot, the turning angle of the idler wheels and the driving wheels is optimal for turning on the spot. When the angle is reached, the striker 14 attached to the rotating part of the driving wheel activates the limit switch 16 attached to the fixed part, turning on the indicator light on the instrument panel, and at the same time activates the solenoid valve 17 attached to the fixed part. A device for holding a driving wheel turning angle of a forklift, characterized in that the pin 18 is fitted into a fixing hole 20 in a turning part to hold the driving wheel at an optimum position during turning.