JPH03159880A - Power vehicle - Google Patents

Abstract

PURPOSE:To carry out safe steering operation by furnishing a control means to change over a transmission to the low speed side when steering of the machine body is set in any mode other than the front wheel steering mode and when the gearing is shifted to the reverse high-speed range side. CONSTITUTION:A managerial tractor of four-wheel drive type is operable in three modes; i.e., front wheel steering mode I, front/rear wheel same-phase steering mode II, and front/rear wheel opposite phase steering mode III. Steering operation is made upon selecting one of these modes, and the transmission is provided with a forward/reverse changeover device and an aux. transmission selectable from at least two positions, high and low. A CPU 20 controls a control valve 28 to control hydraulic clutches 32, 35 of the mentioned forward/ reverse changeover device and another control valve 29 to control hydraulic clutches 39, 40 of the aux. transmission. Controls shall be made so that only the hydraulic clutch 39 on the low speed side is engaged in the modes II, III in which the front and rear wheels are steered simultaneously, and thereby high speed backing of the machine body is checked.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a high-speed reversing restraint mechanism for a power vehicle suitable for passenger management work and the like.

[Prior art and its problems] For maintenance tractors that work across ridges, not only front wheel steering is required. A vehicle capable of air rear transport steering is known. To switch between these steering modes,
The operator switches the steering mode as appropriate depending on the content of the work such as inter-tilling, weeding, and pest control, and the surrounding work conditions such as sloped or flat land. The steering mode and the anti-phase steering mode, in which the front and rear wheels are turned in opposite directions, are generally not familiar to even those who are used to driving cars, so it is dangerous to move the aircraft backwards at high speed.

[Means for Solving the Problems] The present invention is proposed in view of the above problems, and takes the following technical measures.

That is, forward steering mode (I) and longitudinal steering mode (II).
) (III) In a power vehicle configured to enable switching, the traveling transmission section is equipped with a forward/reverse switching device 7 and transmissions 9, 10 capable of switching between at least two high and low gears, The aircraft's steering mode is nose wheel steering mode (I).
), and when the aircraft is shifted to the reverse high speed range side, the transmission device 9 and gear O are switched to the low speed side -2-. Vehicle configuration.

[Embodiments] Hereinafter, embodiments of the present invention will be described with reference to the drawings. First, to explain the configuration, l is a four-wheel immediate-action type management tractor, and the front I! It is equipped with 2, 2 and a later transport 3, 3. The 101 rotational force of the engine 5 is appropriately decelerated via the transmission mechanism in the transmission case 6, and is transmitted to the front transports 2, 2 and the rear transports 3, 3. That is, inside this mission case 6, there is a hydraulic forward/reverse switching device 7 and a 4:. Variable gear 9 and oil K
A sub-transmission device IO capable of switching between two high and low speeds is provided in series. Reference numeral 11 shown in FIG. 2 is a rear differential differential device;
12, No. 2 is the rear shaft final gear mechanism. In addition, in Fig. 2, the front 1lI! Although the drive system is not shown, similar to the rear wheel drive system, reduced rotation is transmitted to the front wheels 2, 2 by transmissions 9, 10 inside the mission case 6. The front wheels 2, 2 and the rear wheels 3, 3 are steered by two hydraulic cylinders 13, 14 of a front wheel steering system and a rear wheel steering system.
! Front wheel steering mode (I) where only 2 and 2 are steered, and front wheel steering mode (I) where front wheels 2 and 2 and rear wheels 3 and 3 are operated in the same direction.
112 in-phase steering mode (II), front transport 2, 2 and rear l
II! A front and rear wheel reverse phase steering mode (II) is provided in which wheels 3 and 3 are steered in opposite directions, and each mode can be switched by the operator using a mode switching dial 16 provided on the side of the steering handle 5 as appropriate. The selection is made based on the

When the operator selects one mode, the hydraulic cylinders l3 and 1 that make up the front wheel steering system and the rear wheel steering system
The oil passage flowing in and out of the cylinder chamber 4 is automatically switched, and when the operator looks at the steering wheel 15 to the right or left, only the direction of the hydraulic oil flowing through that oil passage is switched and the steering is performed in the desired direction. A transaction is made.

Next, the control means, which is the main part of the present invention, will be explained based on the control diagram shown in FIG.

20 is a control device consisting of a CPU, and its -3- human power side is connected to a mode changeover switch 21, a switch 25 operated by a control lever 23 for forward/forward changeover, and a white/manual changeover switch 26. has been done.

On the other hand, a control valve 28 that controls the hydraulic clutch of the forward/reverse switching device 7 and a control valve 29 that controls the hydraulic clutch of the auxiliary transmission 10 are connected to the output side. That is, when the left solenoid 3 of the control button 28 is energized, pressure oil flows into the cylinder chamber of the forward hydraulic clutch 32, and the forward hydraulic clutch 32 is engaged. On the other hand, solenoid 3 on the right side
3 is excited, the reverse hydraulic clutch 35 is connected.

Further, the sub-transmission device 10 is switched between high speed and low speed by moving a sub-transmission lever (not shown) back and forth and operating a high/low speed changeover switch 4. That is, the control valve 29
When the left solenoid 37 is energized, the low-speed hydraulic clutch 39 is activated, and when the right solenoid 38 is energized, the high-speed hydraulic clutch 40 is activated. In addition, in the figure, the reference numeral 45 is a diversion valve, 46 is a hydraulic pump, and 47 is a leaf-4-leaf valve. Further, the control means 20 described above has a built-in program that prevents the aircraft from moving backward at high speed in a mode other than the front wheel steering mode (I).

In this program, the steering mode is the front/rear wheel synchronized phase steering mode (■) or the front/rear wheel reverse phase steering mode (II1).
), when the forward/reverse switching device 147 is switched to the reverse side and the traveling speed is at a high speed, the traveling speed is reduced to a safe speed. A control program is built in to forcibly shift to the lower speed side when the speed is connected to the lower speed side.

In the embodiment described above, when the mode changeover switch 2l is operated to set the front wheel steering mode (I), the front wheel steering mode (I) is set to 1.
, 2 is set to a state in which only the aircraft can be steered, and in this case, the aircraft can be moved forward and backward at the same speed.

However, in the case of modes (II) and (III), in which the forward and backward transports 2, 2, 3, and 3 are simultaneously steered, the safety device that prevents the aircraft from moving backward at high speed is activated, so the aircraft cannot move backward at high speed. Even if the operator attempts to do so, only the low-speed hydraulic clutch 39 is engaged, and therefore there is no danger of the operator being thrown off the aircraft during high-speed retreat.

[Effects of the Invention] Since the present invention is constructed as described above, it has the following technical effects. That is, in the case of the front and rear wheel simultaneous steering modes (I1) (III) with which the operator is not familiar, the control means 2
0 prevents the aircraft from retreating at high speed, so the operator can safely operate the aircraft sideways without feeling uneasy.

4. The diagrammatic explanatory drawings show the embodiments of the present invention; the No. 1 construction drawing is an overall side view, the No. 2 power transmission diagram with some parts omitted, and the No. 3 plan view of the main parts; FIG. 4 is a schematic diagram of the control.

Explanation of symbols Engineering Power vehicle (tractor) 2,2 Pre-export 3, 3 Post-export 7 Forward/forward switching device 7- 1 0 D2 2 0 Main transmission Sub-transmission control means

Claims (1)

[Claims] Front wheel steering mode (I) and front and rear wheel steering mode (II) (II
A power vehicle configured to enable switching of I),
In an aircraft equipped with a forward/reverse switching device 7 and a transmission device 9, 10 capable of switching between at least two high and low gears in the traveling transmission section, when the steering mode of the aircraft is operated to a mode other than the front wheel steering mode (I), and the aircraft is A power vehicle characterized in that a control means 20 is provided for switching the transmission devices 9 and 10 to a low speed side when a speed change operation is performed to a reverse high speed range side.