JPH0629094Y2 - Towing tractor safety device with automatic transmission - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a safety device for an industrial vehicle equipped with an automatic transmission such as a torque converter, particularly a towing tractor used for towing work on an aircraft, a trailer, or the like.

(Prior Art) Generally, in a vehicle equipped with an automatic transmission, the engine always rotates unless the key switch is turned off. In other words, the driver can leave the driver's seat by applying the parking brake while keeping the forward / reverse lever in a position other than the neutral position. Therefore, if such a way of getting off the vehicle is assumed, the vehicle starts to move when the parking brake is weak and the running force of the vehicle exceeds the braking force.

Therefore, as a solution to such a problem, it is decided to stop the fuel supply to the engine when the sensor determines that there is no driving vehicle and the forward / reverse lever is in a position other than the neutral position. A device has been proposed and FIG. 3 shows such a safety device.

This safety device is intended for diesel engine vehicles, and connects a fuel injection amount control device 5 to a battery 1 in series via a key switch 2 and a normally-open relay switch 3 while providing a relay switch. A circuit including a neutral switch 6 for detecting the neutral position of the shift lever of the automatic transmission and a seat switch 7 for detecting the seating state of the driver is connected in series to the relay coil 4 for activating 3 It was done.

That is, the neutral switch 6 and the seat switch 7
When either one of the switches is turned on, the relay coil 4 is excited, the relay switch 3 is turned on, and the engine can be operated. However, when both the switches 6 and 7 are turned off while the engine is being driven. That is, when the driver leaves the driver's seat with the shift lever in the forward position or the reverse position other than the neutral position with the key switch 2 turned on, the excitation of the relay coil 4 is released and the relay switch 3 is turned off. As a result, the power supply to the fuel injection amount control device 5 is cut off.
The fuel cut function, which is one of the functions, is performed and the engine is stopped.

(Problems to be solved by the invention) In the case of the safety device described above, the presence or absence of the driver's seat is determined by the seat switch. Therefore, for example, when the traveling lever is switched to the forward position, the vehicle is When the driver's butt floats up from the driver's seat due to vibrations of the vehicle, the seat switch may be turned off and the engine may be stopped. It is possible to avoid the engine stoppage by installing the. However, especially when the vehicle is moving backward, the hips are more likely to deviate from the center than when moving forward, and the posture tends to be slightly floating. In such a case, it is determined that the driver is absent.

Therefore, among industrial vehicles, particularly in the case of a towing tractor used for towing work on an aircraft or a trailer as shown in FIG. 2, the vehicle is moved backward toward the trailer in order to perform a connecting work with the trailer. In this case, the driver operates the lever 14 to pull up the drawbar of the coupler 13 with one hand to move backward, so that the posture at this time is likely to be in the above-described state, and as a result, it is determined that the driver is absent and the engine is not present. May stop. That is, the conventional safety device is unsuitable for a towing tractor.

Therefore, in view of the above problems, the present invention is a safety device suitable for a towing tractor equipped with an automatic transmission improved so as to prevent a malfunction when the vehicle is traveling in reverse, particularly while operating the coupler while traveling in reverse. The purpose is to provide.

(Means for Solving the Problems) The present invention is configured as follows to solve the above problems.

A switching means is inserted between the key switch and the electric circuit for controlling the engine. For this switching means, a neutral detector for detecting the neutral position of the shift lever in the automatic transmission, and a driver's neutral position. A circuit including a seating detector for detecting a seated state and a drawbar detector for detecting an operating state of an operating lever in the coupler in parallel is connected in series. And
As long as a detection signal is output from any one of the detectors, the switching means is held in the ON state, and when no detection signal is output, the switching means is switched off.

(Operation) In the present invention configured as described above, when the shift lever of the automatic transmission is in the neutral position or when the driver is seated, the switching means is activated by the detection signal from the detector. It is turned on and the engine can be started. When traveling forward, as long as the driver's sitting posture is normal, the ON state of the switching means is maintained by the detection signal from the seating detector, and the operating lever of the connector is operated to perform the connecting work with the trailer. When the vehicle is moving backward, the ON state of the switching means is maintained by the detection signal from the drawbar detector. For this reason, the engine will not stop even when the seating detector does not output a detection signal due to an unnatural seating posture when the vehicle is traveling backwards, particularly when connecting to a trailer or the like. Absent.

On the other hand, when the driver leaves the driver's seat with the shift lever in the forward position or reverse position other than the neutral position, the lever of the coupler is in the non-operating state, and the detection signal from each detector is detected. Is not output, and accordingly, the switching means is turned off and the power supply to the electric circuit for controlling the engine is cut off to stop the engine.

(Embodiment) An embodiment of the present invention, which is embodied for a towing tractor of a diesel engine, will be described below with reference to FIGS. 1 and 2.

In the electric circuit diagram of FIG. 1 showing the safety device of the present embodiment, an electric circuit for controlling an engine, specifically, a device 5 for electrically controlling a fuel injection amount of a diesel engine equipped with a column injection pump (hereinafter, referred to as A fuel injection amount control device) is connected to the battery 1 via a key switch 2 and a relay switch 3 of a normally open type as a switching means.

A relay coil 4 for actuating the relay switch 3 is connected in parallel to a closed circuit including the key switch 2, the relay switch 3 and the fuel injection amount control device 5, and the relay coil 4 is connected to the relay coil 4 of the automatic transmission. The neutral switch 6 for detecting the neutral position, which is turned on when the shift lever is placed in the neutral position, the seat switch 7 for detecting the seating state, which is turned on when the driver is seated, and the draw bar of the coupler is pulled up. Drawbar switch 8 for detecting drawbar pull-up that is turned on when the brake pedal is pressed, and brake pedal switch 9 for detecting footbrake operation that is turned on when the brake pedal is depressed.
And an accelerator pedal switch 10 for detecting an accelerator operation that is turned on when the accelerator pedal is depressed, and a footrest switch 11 for detecting a footrest that is turned on when a foot is placed on the footrest. The circuits are connected in series.

As shown in FIG. 2, among the detection switches, the seat switch 7 is the seat cushion 12 of the driver's seat.
The drawbar switch 8 is mounted in a position where the drawbar switch 8 is operated by an operation lever 14 of a coupler 13 provided at the rear portion of the vehicle body. The neutral switch 6, the brake pedal switch 9, the accelerator pedal switch 10, and the footrest switch 11 are not shown in the drawing, but are set to be detectable at the relevant parts.

The present embodiment is configured as described above, and therefore, when any one of the detection switches forming the parallel circuit is turned on, the relay coil 4 is excited and the relay switch 3 is activated. Since it is turned on, if the key switch 2 is turned on in this state, the fuel injection amount control device 5 is actuated together with the starter (not shown), and the engine is started.

During normal traveling of the towing tractor, the neutral control switch 6 is off because the shift lever of the automatic transmission is in the forward drive position or the reverse drive position. Since the seat switch 7 for seating state detection is ON, the engine continues to rotate. Since the accelerator pedal or the brake pedal is stepped on with the right foot and the left foot is placed on the footrest while traveling, one of the accelerator pedal switch 10 and the brake pedal switch 9 and the footrest switch 11 are placed. Therefore, even if the seat switch 6 is turned off due to insufficient pressure acting on the seat cushion due to the sitting posture of the driver, the engine will not stop.

On the other hand, when the towing tractor is moved backward while operating the operating lever 14 of the coupler 13 toward the drawbar pulling side as shown by the phantom line in FIG. As a result, the hips are likely to come off the center of the seat cushion 12 and the posture tends to float, so that the seat switch 7 may be turned off. At this time, the drawbar switch 8 for detecting the drawbar pull-up is turned on. Therefore, there is no danger of the engine stopping.

That is, in this embodiment, the seat switch 6 is used to indicate the presence of the driver.
By detecting with a switch other than the above, the engine is judged to be absent in spite of the presence of the driver as compared with the conventional safety device that relies only on the seat switch 7 and the engine is judged to be absent. The trouble of being stopped can be prevented in advance.

Then, when the driver leaves the driver's seat by applying the parking brake while keeping the shift lever in the forward position or the reverse position, all the detection switches 6, 7, 8,
9, 10, 11 are turned off, the excitation of the relay coil 4 is released, and the relay switch 3 is turned off, so that the power supply to the fuel injection amount control device 5 is cut off and one function of the fuel injection amount control device 5 is cut off. That is, the fuel supply is cut off when the power is turned off, the engine is stopped, and the vehicle is prevented from running out of control.

Although the present embodiment has been described for a diesel engine vehicle, it can be applied to a gasoline engine vehicle by inserting a relay as a switching means between the key switch and the ignition coil in the ignition device. . Further, the switching means is not limited to the illustrated relay, and for example, a transistor may be used,
Further, each detection switch is not limited to the limit switch.

(Effect of the Invention) As described in detail above, according to the safety device of the towing tractor equipped with the automatic transmission of the present invention, the runaway of the vehicle is prevented when the driver leaves the driver's seat with the engine running. Of course, it is possible to prevent the trouble of stopping the engine due to an erroneous operation of the safety device which may occur when the vehicle moves backward while operating the coupler. Further, since a drawbar pull-up detector such as a switch is simply added, the structure is simple and inexpensive, and the present vehicle can be easily implemented.

[Brief description of drawings]

FIG. 1 is an electric circuit diagram of a safety device showing an embodiment of the present invention,
FIG. 2 is a schematic side view of the towing tractor, and FIG. 3 is an electric circuit diagram of a conventional safety device. 1 ... Battery 2 ... Key switch 3 ... Relay switch 4 ... Relay coil 5 ... Fuel injection amount control device 6 ... Neutral switch 7 ... Seat switch 8 ... Drawbar switch 13 ... Coupler 14 ... Operating lever

Claims (1)

[Scope of utility model registration request] 1. A neutral position detector for detecting a neutral position of a shift lever in an automatic transmission, a switching means inserted between a key switch and an electric circuit for controlling an engine, and a seated state of a driver. A seating detector for detecting and a drawbar detector for detecting the operating state of the operating lever in the coupler are connected in series, and a detection signal from any one of the detectors is connected in series. A safety device for a towing tractor having an automatic transmission configured to hold the switching means in the ON state as long as is output, and switch the switching means to OFF when no detection signal is output.