JPH0790711B2 - Stopping device for variable displacement pump in industrial vehicle - Google Patents

Description

TECHNICAL FIELD The present invention relates to a stop device for a variable displacement pump in an industrial vehicle.

[Conventional technology]

Among the industrial vehicles, the skid steer system includes a drive unit as shown in FIG. That is, a pair of hydraulic motors 53, 54 are provided corresponding to the front and rear wheels 51, 52 respectively provided on the left and right of the vehicle 50, and the hydraulic oil from the variable displacement oil pump 56 driven by the start of the engine 55 is used. Each motor 5
3, 54 rotate, and this rotation is transmitted to the wheels 51, 52 via the chain-sprocket mechanism. Then, as shown in FIG. 5, a pair of steering levers 59 (only one is shown) are provided corresponding to the respective motors 53 and 54, and as shown by the chain double-dashed line, by operating the levers 59 forward and backward, When the swash plate angle of the pump 56 is changed via the steering rod 60, the rotation directions of the motors 53 and 54 change, and the vehicle 50 moves forward and backward. When the lever 59 is released and the operation is stopped, the trunnion lever 62 rotatably provided on the outer wall of the oil pump 56 is urged by the spring S in the spring holder 61, as shown by the solid line. The lever 59 is held in the neutral position and the vehicle 50 is stopped.

[Problems to be Solved by the Invention]

However, the neutral range of the steering lever 59 is possible only when the trunnion lever 62 is held by the spring in the upright posture and the posture slightly inclined from this.
Even if it deviates slightly from this range, the neutrality is not maintained. As described above, in the skid steer loader, it is mechanically difficult to bring the vehicle 50 into the neutral position and accurately stop and hold the vehicle 50.

Further, in the above configuration, the engine 55 is connected and fixed to the pump 56, and the pump 56 is driven at the same time when the engine 55 is started, so that the load applied to the engine 55 becomes extremely large especially at low temperature start, and the engine 55 starts. Cause deterioration of sex.

The present invention has been made to solve the above-described problems, and an object thereof is to stop the vehicle in a stable state and to significantly reduce a load applied to the engine at the time of starting the engine to start the engine. It is an object of the present invention to provide a connecting mechanism for a drive device in a skid steer loader capable of maintaining good performance.

[Means for Solving the Problems]

In order to solve the above-mentioned problems, the first invention of the present application is arranged adjacent to an engine, and is rotatably driven by a variable displacement pump driven by the engine and hydraulic oil supplied from the variable displacement pump, A right drive hydraulic motor that rotates the drive wheel on the right side of the vehicle, a left drive hydraulic motor that rotates the drive wheel on the left side of the vehicle that is rotationally driven by the hydraulic oil supplied from the variable displacement pump, a drive position, and By the switching operation between the stop positions, the switching operation means for the right drive for controlling the variable displacement pump to rotate and stop the hydraulic motor for the right drive, and the switching operation between the drive position and the stop position are performed. In an industrial vehicle equipped with a left drive switching operation means for controlling the variable displacement pump to rotate and stop the left drive hydraulic motor, both of the switching operation means are stopped. When held in location, detection means for detecting this, is interposed between the engine and the pump,
The gist of the invention is to provide a contacting / separating means that connects the two in a detachable manner, and a drive means that drives the contacting / separating means according to the detection result of the detection means to release the connection between the engine and the pump.

Further, the second invention of the present application is a right pump which is disposed adjacent to an engine and is driven to rotate by a variable displacement pump driven by the engine and hydraulic oil supplied from the variable displacement pump to rotate a drive wheel on the right side of the vehicle. Driven by a hydraulic motor and hydraulic fluid supplied from the variable displacement pump,
By the left drive hydraulic motor that rotates the drive wheel on the left side of the vehicle and the switching operation between the drive position and the stop position,
By controlling the variable displacement pump to rotate and stop the right drive hydraulic motor, the right drive switching operation means and by switching between the drive position and the stop position,
In an industrial vehicle equipped with a left drive switching operation means for controlling the variable displacement pump to rotate and stop the left drive hydraulic motor, when both of the switching operation means are held at the stop position, First detecting means for detecting, second detecting means for detecting the leaving of the operator in the driver's seat, contacting / separating means interposed between the engine and the pump for detachably connecting them, and The gist of the invention is to provide an operating means for driving the contacting / separating means to disconnect the engine from the pump in accordance with the detection result of at least one of the first and second detecting means.

[Operation] By adopting the above means, the first invention of the present application makes the engine and the variable displacement pump contact each other when at least one of the right drive switching operation means and the left drive switching operation means rotates the hydraulic motor. When the switching means is connected by the separating means and both the switching operation means are in positions to stop the hydraulic motor, this is detected by the detecting means, and the contacting / separating means releases the connection between the engine and the variable displacement pump by the driving means. By avoiding the operation of the variable displacement pump,
It prevents the hydraulic motor from rotating to start the vehicle.

Further, in the second invention of the present application, when both of the switching operation means are at positions to stop the hydraulic motor, this is detected by the first detection means, and when the driver leaves the driver's seat, The detection means of detects this. The contacting / separating means disconnects the engine from the pump by the action of the driving means according to the detection result of at least one of the first and second detecting means.

〔Example〕

An embodiment in which the present invention is embodied as a stop device for a variable displacement pump in a skid steer loader will be described in detail below with reference to FIGS.

In FIG. 1, an engine 2 is provided at a rear portion (lower portion) of a vehicle 1 of a skid steer loader, and a variable displacement oil pump 4 is connected to the engine 2 via an electromagnetic clutch 3 as a contacting / separating means. There is.

In addition, storage chambers 5 and 6 are provided on both the left and right sides of the vehicle 1, and right and left hydraulic motors 7 and 8 are disposed corresponding to the storage chambers 5 and 6, respectively. Each of the motors 7, 8 is connected to the pump 4 via an oil feed pipe 9 and a return pipe 10, and flows through these pipes 9, 10 to drive the pump 4 and the motors 7, 8
The motors 7 and 8 are rotated by the hydraulic oil circulating between and.

The output shafts 11 and 12 of the motors 7 and 8 respectively enter into the accommodation chambers 5 and 6, and a friction force is applied from a brake drum (not shown) to the brake discs 13 and 14 provided at the entry ends of the motors 7 and 8, respectively. The rotation of 7,8 is stopped. In the storage chambers 5 and 6, the output shafts 11 and 12 of the motors 7 and 8 are the rotary shafts 1 of the front wheels 15 and 16.
7, 18 and the rear wheels 19, 20 are connected to the rotary shafts 21, 22 via the chains 23, 24, and the sprockets (not shown) provided on the rotary shafts 17, 18, 21, 22 and the chains 23, 24 By the action
The rotations of the motors 7 and 8 are transmitted to the front wheels 15 and 16 and the rear wheels 19 and 20 to drive the vehicle 1.

As shown in FIG. 2, a pair of steering levers 26 (only one is shown) serving as a right driving switching operating means and a left driving switching operating means are provided in the driver's cab of the vehicle 1 and are located below the floor F. By rotating back and forth around the provided rotation support shaft 27, the forward and backward positions indicated by the two-dot chain line and the neutral position indicated by the solid line can be continuously switched.

A contact piece 28 is integrally rotatably attached to the upper surface of the rotary support shaft 27, and a changeover switch LS1 (L1L
The electromagnetic clutch 3 is excited and demagnetized by being brought into contact with and separated from the contact of S2). A connecting piece 29 is integrally rotatably attached to the lower surface of the rotation support shaft 27, and a steering rod 30 extending substantially horizontally is attached to the connecting piece 29.
Has one end rotatably attached. The other ends of these steering rods 30 are rotatably supported on the upper portions of a pair of trunnion levers 31 whose central portions are axially supported by the outer wall of the oil pump 4. And the oil pump 4
A spring holder 33 is mounted between a support 32 provided at the end on the engine 2 side and the lower end of the trunnion lever 31, and a spring S provided therein holds the steering lever 26 at a neutral position. Therefore, the trunnion lever 31 is held upright. The center of rotation of the trunnion lever 31 is connected to the swash plate of the pump 4, and when it is rotated, the inclination angle of the swash plate is changed to change the discharge amount of the pump 4.

In the figure, 34 and 35 denote a steering rod and a trunnion lever connected to the other steering lever, and perform the same operation as the above mechanism.

Further, a seat switch 36 as a second detecting means composed of a pressure sensitive switch is provided on the driver's seat 25 arranged on the floor F of the vehicle 1 to detect a change in pressure when the driver sits on or leaves the seat. Then, the electromagnetic clutch 3 is demagnetized and excited.

FIG. 3 shows a drive circuit C as drive means.

That is, in the start switch 37 for turning on and off the electric system of the vehicle 1 by inserting a key, a series circuit of the changeover switch LS1 corresponding to one steering lever 26 and the changeover switch LS2 corresponding to the other steering lever and the seat switch 36. Is connected to the electromagnetic clutch 3 via a parallel circuit composed of. When the electromagnetic clutch 3 is excited, it disconnects the engine 2 from the pump 4, and the changeover switch LS1,
The LS2 is a seat switch 36 which is turned on / off by the contact pieces 28 when the steering lever 26 is in the neutral position and the forward / rearward movement position, and is closed under no pressure.
Is opened and cut when pressure is detected.

Now, the operation of the stop device configured as described above will be described in detail below.

When the driver is seated in the driver's seat 25 and the seat switch 36 is open, the start switch 37 is turned on and the vehicle 1
When both steering levers 26 are held at predetermined positions in order to move straight forward or backward, the current is shut off by the changeover switches LS1 and LS2 that are held open according to this operation, and the electromagnetic clutch 3 Demagnetized, the engine 2 and the oil pump 4 are connected. Therefore, the pump 4 is driven by the operation of the engine 2, the motors 7 and 8 are rotated by the hydraulic oil supplied while the discharge pressure is controlled by the swash plate inclination angle, and the vehicle 1 is moved forward and backward.

When both steering levers 26 are returned to the neutral position in the above state, both selector switches LS1 and LS2 are closed, the electromagnetic clutch 3 is excited, and the connection between the engine 2 and the oil pump 4 is released. Therefore, the neutral state of the steering lever 26 is reliably maintained, and even if an unexpected force is applied to the steering lever 26 and the swash plate tilt angle changes, the contact piece 28 moves and the changeover switches LS1, LS2 are turned off. The vehicle 1 will not start unless the electromagnetic clutch 3 is demagnetized.

When turning the vehicle 1, if one of the steering levers 26 is moved in the front-rear direction from the neutral position, one of the changeover switches LS1 or LS2 is opened, the electromagnetic clutch 3 is demagnetized, and the engine 2 and the oil pump 4 are connected. At the same time, the inclination angle of the swash plate is changed by the steering lever 26, and the operating oil is supplied to the corresponding motors 7, 8, so that either the left or right front wheel 15, 16 and the rear wheel 20, 21 are Is rotated. And the front and rear wheels 15,
The vehicle 1 turns by the rotation of 16, 20, and 21.

Further, since the steering lever 26 is in the neutral position when the start switch 37 is turned on in order to start the engine 2 prior to the start of the vehicle 1, the electromagnetic clutch 3 is in the energized state and the pump 4 for the engine 2 is activated. Has been withdrawn. Therefore, unlike the conventional product, starting of the engine 2 and driving of the pump 4 by the engine 2 are not performed at the same time, and the load on the starting of the engine 2 is reduced.

Further, when the vehicle 1 is temporarily stopped or the like, when the driver gets off the vehicle while the steering lever 26 is held in the neutral position and the engine 2 is operated without turning off the start switch 37, the driver can move from the driver seat 25. As the user leaves the seat, the seat switch 36 is turned on and the electromagnetic clutch 3 is excited. Therefore, the connection between the engine 2 and the pump 4 is released, the operation of the pump 4 is stopped, and even if a part of the driver's body touches the steering lever 26 in a small driver's cab, the steering lever 26 is tilted and the vehicle 1 is tilted. Will never start.

〔effect〕

As described above in detail, according to the present invention, the vehicle of the skid steer system in which the right drive wheel and the left drive wheel are independently operated by the switching operation means can be stopped in a stable state and the engine can be started. At times, the load applied to this is greatly reduced, and the excellent start-up performance can be achieved especially at low temperatures.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a drive system of a skid steer loader, FIG. 2 is a partially cutaway side view showing a steering lever switching device, and FIG. 3 is a circuit diagram showing an electrical configuration of the present invention, FIG. 5 and 5 are an explanatory view and a partially cutaway side view showing a conventional example, respectively. Engine 2, electromagnetic clutch 3 as a contacting / separating means, variable displacement pump 4, hydraulic motors 7, 8 for right driving and left driving,
A steering lever 26 as a right drive switching operation means and a left drive switching operation means, a seat switch 36 as a second detecting means, a drive circuit C as a driving means, and changeover switches LS1, LS2 as a first detecting means.

Claims (2)

[Claims] 1. A variable displacement pump which is disposed adjacent to an engine and is driven by the engine, and a right drive which is rotationally driven by hydraulic oil supplied from the variable displacement pump to rotate a drive wheel on the right side of the vehicle. Hydraulic motor, a left drive hydraulic motor that is driven to rotate by the hydraulic oil supplied from the variable displacement pump, and rotates the drive wheel on the left side of the vehicle, and is switched between a drive position and a stop position. ,
By controlling the variable displacement pump to rotate and stop the right drive hydraulic motor, the right drive switching operation means and by switching between the drive position and the stop position,
An industrial vehicle having a left drive switching operation means for controlling the variable displacement pump to rotate and stop the left drive hydraulic motor, and when both of the switching operation means are held at a stop position, Detecting means for detecting, contacting / separating means interposed between the engine and the pump to detachably connect them, and driving the contacting / separating means according to the detection result of the detecting means to release the connection between the engine and the pump. A stop device for a variable displacement pump in an industrial vehicle, which is provided with a driving means for driving the same. 2. A variable displacement pump which is disposed adjacent to an engine and is driven by the engine, and a right drive which is rotationally driven by hydraulic oil supplied from the variable displacement pump to rotate a drive wheel on the right side of the vehicle. Hydraulic motor, a left drive hydraulic motor that is driven to rotate by the hydraulic oil supplied from the variable displacement pump, and rotates the drive wheel on the left side of the vehicle, and is switched between a drive position and a stop position. ,
By controlling the variable displacement pump to rotate and stop the right drive hydraulic motor, the right drive switching operation means and by switching between the drive position and the stop position,
An industrial vehicle having a left drive switching operation means for controlling the variable displacement pump to rotate and stop the left drive hydraulic motor, and when both of the switching operation means are held at a stop position, First detecting means for detecting, second detecting means for detecting the leaving of the operator in the driver's seat, contacting / separating means interposed between the engine and the pump for detachably connecting them, A stop device for a variable displacement pump in an industrial vehicle, comprising: a drive unit that drives a contact / separation unit according to a detection result of at least one of the first and second detection units to disconnect the engine from the pump.