JP2009168149A - Hst control device for work vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydrostatic transmission (HST) control device for a work vehicle operating a hydraulic pump, and traveling and moving the vehicle even if there is something wrong with a controller controlling an HST or electric wiring transmitting the signal of the controller is disconnected. <P>SOLUTION: This HST control device includes: the controller outputting the electric signal controlling a discharge of oil from a variable displacement pump; a solenoid proportional valve connected to the controller, and outputting a hydraulic signal in response to the output from the state in which there is no output of the electric signal and the discharge of oil is zero, to the capacity controller of the variable displacement pump; and a backup circuit arranged between the controller and the solenoid proportional valve, and having a switch switching the solenoid proportional valve to the controller or a battery as a power supply for the vehicle. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a work vehicle HST control device, and more particularly to a work vehicle control device equipped with an electronically controlled HST.

Many work vehicles such as wheel loaders, tractors, and bulldozers are equipped with a well-known electronically controlled HST including a hydraulic pump / motor that is an electronically controlled continuously variable transmission (see, for example, Patent Document 1).
Japanese Patent Laid-Open No. 11-63218 (FIG. 1)

  The work vehicle equipped with the electronically controlled HST as described above has the following problems to be solved.

  That is, in the electronically controlled HST, the electrical signal of the controller is changed to a hydraulic signal by an electromagnetic proportional valve, and the displacement controller of the variable displacement hydraulic pump is operated by this hydraulic signal to discharge a predetermined amount of hydraulic oil. Controlling driving. Therefore, when the electrical signal is not output due to a malfunction of the controller, or when the electrical wiring to the electromagnetic proportional valve is disconnected, the hydraulic pump cannot be controlled to discharge hydraulic oil, so the vehicle can be run. The vehicle cannot be moved.

  For example, when the vehicle is unable to run due to a controller malfunction or disconnection, it is difficult to identify the cause and repair on site is difficult. In particular, a large amount of money is required to move a vehicle at a site with a poor footing or a remote site.

  The present invention has been made in view of the above-mentioned facts, and its technical problem is also in a work vehicle equipped with an electronically controlled HST, such as a failure of a controller that controls the HST, a disconnection of an electrical wiring that transmits a controller signal, and the like Another object of the present invention is to provide an HST control device for a work vehicle that can operate and move a hydraulic pump to move the vehicle.

  According to the present invention, as an HST control device for a work vehicle that solves the above technical problem, a controller that outputs an electric signal for controlling the amount of oil discharged from a variable displacement pump of an electronically controlled HST, and a variable connected to the controller are provided. An electromagnetic proportional valve that outputs a hydraulic signal according to the output from a state where the discharge oil amount is zero and no electric signal is output to the displacement controller of the displacement pump, and is provided between the controller and the electromagnetic proportional valve. Provided is a work vehicle HST control device including a backup circuit having a switch that can switch a valve to a controller or a battery that is a power source of the vehicle.

  Preferably, the backup circuit includes output adjusting means for adjusting an electric signal to the electromagnetic proportional valve between the battery and the switch. Further, the backup circuit is connected to an output section when the power switch that connects the battery to the electric load of the vehicle is ON.

  An HST control device for a work vehicle configured in accordance with the present invention includes a controller that outputs an electric signal for controlling the amount of oil discharged from a variable displacement pump, and the controller connected to the controller. An electromagnetic proportional valve that outputs a hydraulic signal corresponding to the output from a zero discharge oil amount state without output, and is provided between the controller and the electromagnetic proportional valve, and the electromagnetic proportional valve is connected to a battery that is a power source of the controller or vehicle. Has a backup circuit with switchable switch

  Therefore, if the vehicle cannot run due to a failure of the controller that controls the HST or a cause such as disconnection of the electrical wiring that transmits the controller signal to the electromagnetic proportional valve, the switch is switched and the electromagnetic proportional valve is connected to the vehicle battery. By connecting and operating the hydraulic pump with this electrical signal, the vehicle can be run and moved.

  Hereinafter, an HST control device for a work vehicle configured according to the present invention will be described in more detail with reference to the accompanying drawings illustrating a preferred embodiment.

  A wheel loader that is a typical work vehicle will be described with reference to FIG. The wheel loader 2 includes a front vehicle body 8 including a front wheel 4 and a work device 6, and a rear vehicle body 16 including a rear wheel 10, an engine compartment 12, and a cab 14.

  1 will be described with reference to FIG. 1 and mainly FIG. The wheel loader 2 includes a known electronically controlled HST 22 having a variable displacement hydraulic pump 18 driven by the engine 12 a in the engine compartment 12 and a hydraulic motor 20 that drives the wheels 4 and 10. The variable displacement hydraulic pump 18 is, for example, a swash plate piston type pump, and the displacement controller 18a operates the inclination of the swash plate to control the intermittent discharge, oil amount, direction, and the like of the hydraulic oil.

  The HST control apparatus generally indicated by reference numeral 24 is connected to the controller 26 that outputs an electric signal for controlling the discharge of the variable displacement pump 18 of the HST 22, and is connected to the controller 26 a of the variable displacement pump 18. Is provided between the controller 26 and the electromagnetic proportional valve 28. The electromagnetic proportional valve 28 is provided between the controller 26 or the vehicle power supply. A backup circuit 34 having a switch 32 that can be switched to the battery 30 is provided.

  The controller 26 is included in an electronic control module (ECM) 36 of the wheel loader 2. For example, the controller 26 outputs an electrical signal corresponding to the operation of the travel lever operated by the operator of the cab 14 (FIG. 2).

  The backup circuit 34 includes a variable resistor 38 between the battery 30 and the switch 32 as output adjusting means for adjusting an electric signal to the electromagnetic proportional valve 28. This backup circuit 34 is connected to the output section when the power switch 40 that connects the battery 30 to the electric load 40 of the vehicle is ON. If the electric signal can be adjusted to a fixed value, the output adjusting means 38 may be a fixed resistor.

  As described above, when the switch 32 is switched to the battery 30 side and the battery 30 is used as an electrical signal source in place of the controller 26, the variable capacity pump 18 operates in an amount that allows the vehicle (wheel loader) 2 to travel. As long as the oil can be discharged, there is no need to finely control the electrical signal and finely control the amount of discharged oil. The operator operates an accelerator pedal (not shown) in the cab 14 to adjust the output rotational speed of the engine 12a and adjust the amount of oil discharged from the variable displacement pump 18, so that the traveling movement speed is set according to the amount of oil. Adjustable to speed.

  The operation of the HST control device 24 for a work vehicle as described above will be described with reference to FIG.

  The HST control device 24 is connected to the controller 26 that outputs an electric signal for controlling the amount of oil discharged from the variable displacement pump 18, and is discharged to the displacement controller 18 a of the variable displacement pump 18 without output of an electric signal. An electromagnetic proportional valve 28 that outputs a hydraulic signal corresponding to the output from a state where the oil amount is zero, and a controller 26 and an electromagnetic proportional valve 28 are provided. The electromagnetic proportional valve 28 is connected to the controller 26 or a battery 30 that is a power source of the vehicle. A backup circuit 34 having a switch 32 that can be switched is provided.

  Therefore, when the hydraulic pump 18 cannot be controlled due to a malfunction of the controller 26 that controls the HST 20 or disconnection of the electrical wiring that transmits the signal of the controller 26 to the electromagnetic proportional valve 28, the switch 32 is switched to switch the electromagnetic proportional valve 28 to the vehicle battery. The vehicle can be run and moved by operating the hydraulic pump 18 with an electrical signal from the battery 30 connected to the vehicle 30.

  The backup circuit 34 includes an output adjusting means 38 formed of a variable resistor or a fixed resistor for adjusting an electric signal to the electromagnetic proportional valve 28 between the battery 30 and the switch 32. Therefore, by adjusting the electric signal to the electromagnetic proportional valve 28 by the variable resistor 38, the amount of oil discharged from the variable displacement pump 18 can be adjusted to adjust the traveling speed of the work vehicle 2.

  The backup circuit 34 is connected to the output section when the power switch 42 that connects the battery 30 to the electric load 40 of the vehicle is ON. Therefore, the backup circuit 34 is directly connected to the battery 30 of the power supply directly without going through the electric system in the middle, and further when the engine 12a is operated to drive the variable capacity pump 18 with the power switch 42 turned ON. The battery 30 is securely connected.

The structure explanatory view of the HST control device of the work vehicle constituted according to the present invention. The side view of the wheel loader which is a typical example of the work vehicle provided with the HST control apparatus shown in FIG.

Explanation of symbols

2: Wheel loader (work vehicle)
18: Variable capacity pump 18a: Capacity controller 22: HST
26: controller 28: electromagnetic proportional valve 30: battery 32: switch 34: backup circuit 38: variable resistance (output adjusting means)
40: Electric load 42: Power switch

Claims (3)

A controller that outputs an electrical signal for controlling the amount of oil discharged from the variable displacement pump of the electronically controlled HST;
An electromagnetic proportional valve connected to the controller and outputting a hydraulic signal corresponding to the output from the state of zero discharge oil amount without output of an electric signal to the displacement controller of the variable displacement pump;
A backup circuit having a switch provided between the controller and the electromagnetic proportional valve and capable of switching the electromagnetic proportional valve to a battery that is a power source of the controller or the vehicle. apparatus. The backup circuit
An output adjusting means for adjusting an electric signal to the electromagnetic proportional valve is provided between the battery and the switch;
The HST control device for a work vehicle according to claim 1. The backup circuit
Connected to the output part when the power switch for connecting the battery to the electric load of the vehicle is ON,
The HST control device for a work vehicle according to claim 1 or 2.

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