JPH03153477A - Steering system for crawler type vehicle - Google Patents

Abstract

PURPOSE:To achieve steerage with the same sense as in an automobile by connecting each of symmetrical hydraulic pumps to a gear shaft of a sun gear in a symmetrical pair of traveling planetary reduction gear mechanism directly, and installing a solenoid relief valve, where setting pressure is controlled in proportion to a current-energization value, in each discharge route of these hydraulic pumps. CONSTITUTION:In this steering system, there are provided with a symmetrical pair of traveling planetary reduction gear mechanisms 5, 6 to which output of an engine 1 is transmitted via bevel gears 2, 3, and symmetrical hydraulic pumps 10, 11 are directly connected to a gear shaft 9 of a sun gear 8 in these reduction gear mechanisms 5, 6. Solenoid relief valves 15, 16 in which setting pressure is controlled in proportion to a current-energization value are installed in each discharge route of these hydraulic pumps 10, 11. Then, each setting pressure of these solenoid relief valves 15, 16 is controlled by a controller 17 according to output of a steering angle sensor 19 interlocking with a steering wheel 18 whereby each load of these hydraulic pumps 10, 11 is enlarged, thereby making it act as a brake to drive of a crawler and so as to achieve steerage.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a steering device for a crawler-type vehicle that uses a crawler as a traveling means.

(Prior Art) Crawler-type vehicles such as bulldozers, excavators, and cranes are steered by a skid steer system, which is an indirect steering system. In this skid steer type steering, when the vehicle is slowly turned, the rotational speeds of the left and right crawlers are made different. Also, when making a sharp turn, the left and right crawlers are completely stopped.

Conventionally, skid steer type steering devices for roller type vehicles have been provided with left and right steering clutches and brakes that transmit engine output to the left and right crawler drive wheels, and these steering clutches and brakes are It was controlled by left and right steering levers.

(Problem to be Solved by the Present Invention) However, in such a conventional device, since steering control is performed while tilting the steering lever back and forth, the inclination angle of the steering lever and the turning angle of the vehicle are If you don't know it from experience, you won't be able to perform smooth steering control. Therefore, there is a problem in that a skilled person is required to steer a vehicle equipped with this type of device.

In addition, since steering control is performed via the steering clutch and brake, for example, if the steering control is repeated within a range of minute rotation angles, the steering clutch and brake will slip more, resulting in loss. There are no problems with horsepower generation.

The first object of the present invention is to provide a steering device for both crawlers LFJ and TLT that provides a smooth operation feeling and does not generate loss of horsepower even when making repeated small-angle turns eastward.

(Top step to solve the problem) The crawler type eastward steering device of the present invention includes a left steering speed reduction device that transmits the engine output to the left and right crawler drive wheels, and a left steering speed reduction device that transmits engine output to the left and right crawler drive wheels, and connected,
The left and right hydraulic pumps rotate by their output, the left oil passage connecting the discharge side of these hydraulic pumps and the oil tank, the left electromagnetic relief valve sunk into these oil passages, and the steering angle of the steering wheel. The electromagnetic relief valve is characterized in that it is configured to change the set pressure in accordance with the amount of energization.

(Action of the present invention) In the device of the present invention, when the vehicle travels, the hydraulic pump is driven via the steering speed reduction device. At this time, the set pressures of the left and right electromagnetic relief valves change depending on the rotation angle of the steering wheel. Therefore, the loads on these left and right hydraulic pumps change depending on the set pressure of the electromagnetic relief valve.

Since the rotational speed of the steering reduction gear is controlled by the load on the hydraulic pump, the traveling speed of the left Ji crawler also differs as a result. Therefore, the vehicle will be steered in the desired direction.

(Embodiment of the present invention) In the illustrated embodiment, the output of the engine 1 is transmitted to the main shaft 4 via a pair of hevel gears 2.3. This main shaft 4
The rotational force is transmitted to the left crawler drive wheel (not shown) via left and right steering planetary reduction devices 5.6 disposed at both ends of the main shaft 4.

Note that a main clutch and a transmission (not shown) are interposed between the engine 1 and the main shaft 4. Therefore, when the main clutch is in the on state, the output of the engine 1 is shifted by the transmission, and the -L shaft 4. It is transmitted to the left and right crawler drive wheels via the left B steering planetary reduction device 5.6.

The planetary speed reduction device 5.6 for both steering inputs the engine output to each planetary gear 7 and outputs it from the sun gear 8.
A shaft 9 of this sun gear 8 is connected to each crawler drive wheel.

-F The left and right hydraulic pumps 10.11 are directly connected to the sun gear shaft 9 of both planetary reduction gears 5.6. Therefore, both hydraulic pumps 10, 11 are operated by the rotation of the sun gear shaft 9. And an oil passage 13.14 connecting this hydraulic pump 10.11 and the tank 12.
are provided with electromagnetic relief valves 15 and 16. The set pressure of the electromagnetic relief valves 15, 16 is controlled in proportion to the amount of current supplied thereto.

The amount of current supplied to the electromagnetic relief valves 15 and 16 is controlled by control signals C1 and C2 from a controller 17, which is connected to a steering angle sensor 19 that detects the steering angle of the steering wheel 18. ing.

When the steering wheel 18 is kept in the neutral position, the amount of current flowing through the electromagnetic relief valves 15 and 16 is zero.

When the amount of current applied to the electromagnetic relief valves 15, 16 is zero, the set pressures of both electromagnetic relief valves 15, 16 are similarly set close to zero. For example, when the steering wheel 18 is turned to the right,
The set pressure of the electromagnetic relief valve 15 on the right side becomes high, and the set pressure of the electromagnetic relief valve 16 on the left side becomes low. Further, when the steering wheel 18 is turned to the left, the set pressure of the left electromagnetic relief valve 16 becomes high, and the set pressure of the right electromagnetic relief valve 15 becomes low.

Next, the operation of this embodiment will be explained.

When driving engine 1 to drive the vehicle,
The rotational force of the single shaft 4 is transmitted to the sun gear 8 via the planetary gear 7, and the rotational force is transmitted to the shaft 9 of the sun gear 8.
is output from. Therefore, a crawler (not shown) linked to the sun gear shaft 9 is driven to cause the vehicle to travel.

When the crawler is driven in this manner, the hydraulic pump 10.11, which is also connected to the sun gear shaft 9, also rotates and discharges a flow rate corresponding to its rotational speed. This hydraulic pump 10.1
The flow rate discharged from 1 flows into the tank 12 via the electromagnetic relief valve 15.16, but the relief valve 1 at this time
5.16 The higher the set pressure, the more the hydraulic pump 10
．． 11 load increases. The loads of the hydraulic pumps 10 and 11 act as a brake on the drive of the crawler.

If the steering wheel 18 is kept in the middle q position, the set pressures of both electromagnetic relief valves 15 and 16 will similarly be close to zero, so the load on the internal hydraulic pump 10 and 11 will also be close to zero. . In this way, the internal hydraulic pump 1
If the load on O111 is the same, the braking force on the crawler will also be the same. Therefore, at this time, the vehicle will be traveling straight.

If the steering wheel 18 is turned to the right, for example, the steering angle sensor 19 detects this and transmits it to the controller 17. The controller 17 that receives the signal from the steering angle sensor 19 outputs a control signal C according to the signal.
I and C2 are output, the set pressure of the electromagnetic relief valve 15 on the right side is made high, and the set pressure of the electromagnetic relief valve 16 on the left side is kept low.

Therefore, a braking force corresponding to the increased load acts on the right crawler, and the braking force does not act on the left crawler. Therefore, the drive speed of the right crawler becomes H compared to the left crawler, so the vehicle is steered to the right.

On the other hand, if the steering wheel 18 is turned to the left, the set pressure of the left electromagnetic relief valve 16 will be higher, so the vehicle will be steered to the left based on the same principle as described above.

5 As mentioned above, according to the device of this embodiment, by turning the steering wheel 18, the electromagnetic relief valve 1
5.16 set pressure and hydraulic pump 10
．． Since the load pressure of 11 is controlled, the loss in power transmission is reduced compared to the conventional system using a clutch and brake.

In addition, since the steering can be controlled by turning the steering wheel 18, the steering feeling becomes smoother.
Even non-experts can easily operate it.

(Effects of the present invention) According to the device of the present invention, since it is possible to perform steering using the steering wheel, even when performing minute angle control, it does not require much skill, and smooth steering can be achieved as a whole. .

Furthermore, since the braking force is controlled by controlling the load on the hydraulic pump, there is no loss in power transmission due to slipping, which occurs in conventional systems that use clutches and brakes.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an embodiment of the present invention. 1... Engine, 5.6... Planetary reduction gear for steering,
10.11-... Hydraulic pump, 12... Tank, 13
．． 14... Oil passage, 15.16... Electromagnetic relief valve, 18... Steering wheel.

Claims (1)

[Claims] The left and right steering reduction devices transmit engine output to the left and right crawler drive wheels, the left and right hydraulic pumps that are connected to these steering reduction devices and rotate by their output, and the discharge sides of these hydraulic pumps and oil Left and right oil passages connecting the tank, left and right electromagnetic relief valves installed in these oil passages,
A crawler comprising: a controller that controls the amount of electricity supplied to the electromagnetic relief valve according to the steering angle of a steering wheel, and the electromagnetic relief valve is configured to change a set pressure according to the amount of electricity supplied Steering device for type vehicles.