JPH0735222U - Control device for auxiliary brake in industrial vehicle - Google Patents

Abstract

(57) [Summary] [Purpose] Apply auxiliary braking suitable for cargo handling conditions. [Structure] When the brake pedal 10 is depressed or the retarder switch 31 is turned on, the electromagnetic retarder 25
Works. The load applied to the fork 43 on which the load is placed is detected by the load detector 60. The height detector 62 detects the height of the fork 43. The control unit 30 first uses these detection signals to determine the retarder 25 based on the load.
After determining the braking torque of, the correction is performed so that the braking torque becomes a little lower as the load height becomes higher. The electric power supplied to the magnetic coil of the retarder 25 is determined so that the braking torque is optimal for the current state.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a retarder as an auxiliary brake for a service brake in industrial vehicles such as forklifts and wheel loaders.

[0002]

[Prior art]

 In conventional industrial vehicles, engine braking and service braking are used together to obtain control. The service brake obtains a braking force by applying hydraulic pressure or pneumatic pressure to the brake device provided on the wheel when the foot pedal is depressed.

However, when the vehicle is under a heavy load such as when carrying a heavy load, or when the load of the service brake is heavy for work that requires frequent brake operations, an assistance is provided to reduce the load. A retarder is provided as a brake. This retarder is mounted on a drive transmission shaft of a drive transmission system that transmits the driving force from the engine to the wheels.

[0004]

[Problems to be solved by the device]

 Although a certain braking torque is generated by the retarder, it cannot be adjusted depending on the vehicle condition. That is, in a 10-ton forklift, the vehicle weight is 13200 kg and the load is 10000 kg, and the total vehicle weight is 23200 kg when loaded and 13200 kg when not loaded, which greatly changes depending on the situation. If the retarder is set so that effective braking torque can be obtained under load, the braking torque becomes too large when the load is small, and sudden deceleration is dangerous. In addition, if the vehicle is suddenly decelerated while lifting a load, there is a risk that the load may collapse or the vehicle may topple over.

In view of the above, it is an object of the present invention to provide a control device for an auxiliary brake that adjusts the braking torque of the retarder according to the load applied to the vehicle or the state of the load.

[0006]

[Means for Solving the Problems]

 As shown in FIG. 1, the problem solving means according to the present invention is an industrial vehicle provided with a retarder 25 for an auxiliary brake in a power transmission system for transmitting a driving force from an engine 4 to a wheel, and an industrial vehicle including a cargo handling device 9. A load detector 60 that detects the load applied to the device 9, a state detector that detects the state of the cargo handling device 9, and a control unit 30 that changes the braking force by the retarder 25 according to the load and the state are provided. It has been done.

[0007]

[Action]

 In the above problem solving means, the retarder 25 is operated while traveling while operating the cargo handling device 9. At this time, the load exerted on the cargo handling device 9 is detected by the load detector 60, and the height and inclination of the load are also detected by the state detector. The control unit 30 drives the retarder 25 by outputting an output signal to the retarder 25 based on these detection signals so that the braking torque is optimum for the cargo handling state. As a result, smooth deceleration is performed.

[0008]

【Example】

 As shown in FIG. 2, the large forklift truck of this embodiment has two left and right drive wheels 2 mounted on the front side of the vehicle body 1 and one left and right steering wheel 3 mounted on the rear side. An engine 4, a torque converter 5, and a trans mission 6 are arranged in the center of the vehicle body 1, a differential 8 is connected to the transmission 6 via a propeller shaft 7, and left and right front axle shafts are connected to the differential 8. The drive transmission system is constituted by these components. A cargo handling device 9 is arranged on the front side of the vehicle body 1.

The service brake is provided with an inching mechanism. As shown in FIG. 1, the service brake and the inching mechanism use a common air-over-hydro type fluid pressure circuit and are installed in the cab. Brake valves 12 and 13 are attached to the brake pedal 10 and the inching pedal 11, respectively. Each of the brake valves 12 and 13 changes the air pressure according to the amount of depression of the pedal.

The lower chamber 13a of the inching side brake valve 13 is connected to the air tank 14, and the lower chamber 13a of the inching side brake valve 13 and the lower chamber 12a of the brake side brake valve 12 are always in communication with each other.

The upper chamber 12 b of the brake side brake valve 12 is connected to the booster 16 via a double check valve 15. The booster 16 uses the air pressure controlled by the brake valves 12 and 13 as a pilot pressure to take in high-pressure air from the main tank into the power piston section, and converts the oil in the hydraulic cylinder into high pressure to distribute it to each wheel. The wheel brake 17 has been activated.

The upper chamber 13 b of the inching side brake valve 13 is connected to an inching valve 19 that connects and disconnects the clutch of the transmission 6 by an inching circuit 18, and is also connected to a double check valve 15. As a result, the clutch is disengaged and the brake is operated by operating the inch pedal 11.

Further, a brake operation detector 20 for detecting the depression of the brake pedal 10 is provided, which is composed of a pressure sensor for detecting the discharge pressure of the brake valve 12, and is provided between the brake valve 12 and the double check valve 15. It is located in.

An electromagnetic retarder 25 is provided as an auxiliary brake on the power transmission shaft of the power transmission system. That is, the retarder 25 is mounted on any one of the output shaft of the transmission 6, the intermediate portion of the propeller shaft 7, the differential 8, and the front axle shaft.

The electromagnetic retarder 25 has a rotor and a stator composed of a plurality of magnetic coils, and reduces or controls the speed of the vehicle by utilizing the deceleration force due to the eddy current when the rotor is rotated in a magnetic field. It is a thing. As shown in FIG. 3, the stator magnetic coils 1N and 1'N are connected to the first terminal 26, the magnetic coils 2N and 2'N are connected to the second terminal 27, and the magnetic coils 3S and 3'S are connected to the third terminal 28. The magnetic coils 4S and 4'S are connected to the fourth terminal 29, and the terminals 26, 27, 28 and 29 are connected to the control unit (microcomputer) 30.

The operation of the retarder 25 is performed by operating the retarder switch 31, and the retarder switch 31 is arranged in the operator's cab along with an elevating lever 32 and a tilt lever 33 described later. Further, the retarder 25 has a characteristic that the braking torque generated in the retarder 25 becomes large as the electric power supplied to each magnetic coil is increased as shown in FIG.

The cargo handling device 9 includes a fixed mast 40 provided upright on the front portion of the vehicle body 1, an elevating mast 41 guided by the fixed mast 40 so as to be vertically movable, and a lifting mast 41 via a bracket. It is provided with a finger bar mounted to be able to move up and down, a pair of forks 43 mounted on the finger bar, a pair of lift cylinders 44 for moving the lifting mast 41 up and down, and a tilt cylinder 45 for tilting the fixed mast 40. .

As a lifting mechanism for the fork 43, as shown in FIG. 5, the chain 46 fixed to the chain fixing portion 43a of the fork 43 is wound around the pulley 47 and the other end of the chain fixing piece of the fixed mast 40. It is fixed to 48. The pulley 47 is rotatably supported by a support piece 49 vertically provided on the frame 41a of the lifting mast 41. As a result, when the lift cylinder 44 extends, the elevating mast 41 is pushed up, and as the pulley 47 rises, the chain 46 is also lifted and the fork 43 rises.

The cargo handling device 9 is driven by hydraulic pressure, and as shown in FIG. 6, a mast control valve 50 for controlling the hydraulic pressure to the pair of lift cylinders 44 is provided. The mast control valve 50 operates the lifting lever 32. It is driven by a lift pilot valve 51 operated by. Similarly, the tilt cylinder 45 is also provided with a tilt control valve 52 and a tilt pilot valve 53, and the tilt control valve 52 is driven by operating the tilt lever 33. In the figure, 54 is a pump and 55 is a pilot relief valve.

Here, the braking torque of the retarder 25 is changed by the control unit 30 according to the load applied to the cargo handling device 9 and the states such as the height of the load and the front-back position. Therefore, a load detector 60 that detects the load applied to the cargo handling device 9 and a state detector that detects the state of the cargo handling device 9 are provided.

The load detector 60 is composed of a pressure sensor interposed in a hydraulic circuit that supplies the hydraulic pressure from the mast control valve 50 to the lift cylinder 44, and the load applied to the fork 43 is detected. Further, as state detectors, there are a mast tilt detector 61 that detects the tilt of the fixed mast 40 and a height detector 62 that detects the height of the fork 43. The mast tilt detector 61 includes the tilt control valve 52. The height sensor 62 is composed of a rotation sensor integrally attached to the pulley 47 of the chain 46 as shown in FIG. By detecting the number of rotations and the direction of rotation of the pulley 47, the height of the fork 43 lifted is detected. In FIG. 5 (b), 63 is a switch for detecting the lower limit position of the fork 43, and 64 is a protrusion corresponding to the lower limit position. The height reference value can be known from these.

The detection signal from each detector is input to the control unit 30, and the control unit 30 controls the braking torque of the retarder 25 according to the load and the state of the cargo handling device 9. That is, it has a function of increasing the braking torque of the retarder 25 as the load increases, and a function of decreasing the braking torque of the retarder 25 as the load becomes higher while also considering the inclination. . The retarder 25 is operated by turning on the retarder switch 31 or depressing the brake pedal 10 by the brake operation detector 20.

In the above structure, when the vehicle is decelerated while traveling while carrying a load on the fork 43, the retarder 25 is operated by depressing the brake pedal 10 or turning on the retarder switch 31. At this time, hydraulic pressure is applied to the lift cylinder 44 so that the loaded fork 43 does not descend, and this hydraulic pressure is detected by the load detector 60. Further, when the fork 43 is raised, its height is detected by the height detector 62, and when the fixed mast 40 is inclined, the inclination is detected by the mast inclination detector 61. The control unit 30 determines the electric power to be supplied to the magnetic coil so as to obtain the optimum braking torque for the current state based on these detection signals, and drives the retarder 25 accordingly.

For example, after first determining the braking torque of the retarder 25 based on the load, the braking torque is corrected so that the braking torque becomes slightly lower as the load height becomes higher. Further, if the fixed mast 40 is tilted backward, the possibility of load collapse is small, so correction is made to suppress the rate of reducing the braking torque.

Therefore, the braking torque of the retarder becomes appropriate according to the load and the state of the load, so that smooth deceleration can be performed. Therefore, there will be no load collapse or overturn due to sudden deceleration or excessive braking, and safe and comfortable braking can be obtained. Further, the braking force can be obtained without imposing a burden on the service brake, and braking can be performed by the retarder while operating the cargo handling device, so that operability can be improved.

In the above-described embodiment, the braking torque of the retarder is increased as the load increases, but impact may be strictly prohibited depending on the type of load. Also, if the loads themselves are slippery, they must be shocked so that they do not collapse when stacked and transported. On the other hand, the above retarder control cannot deal with these problems. Therefore, conversely to the above, the control unit is provided with a function of reducing the braking torque of the retarder as the load increases. Then, in order to execute this function, a changeover switch is provided, and control is performed to reduce the braking torque of the retarder by turning on the changeover switch for a special load. Take control of the example. Therefore, the braking force of the retarder can be selectively used depending on the load, and the safety can be further improved.

It should be noted that the present invention is not limited to the above embodiment, and it goes without saying that many modifications and changes can be made to the above embodiment within the scope of the present invention.

As the retarder, a fluid type retarder may be used instead of the electromagnetic type. In this case, the braking torque of the retarder is controlled by the hydraulic pressure. Further, as the brake operation detector, a position detection switch such as a potentiometer or a limit switch may be used instead of the pressure sensor. As a load detector, a displacement detector such as a strain gauge may be provided on both the front and rear axles or on either one of the axles. The height detector may be a potentiometer or limit switch. However, in the case of a limit switch, a plurality of limit switches are provided according to the height position, and the braking torque of the retarder is gradually changed each time it is turned on.

Alternatively, only the load may be detected, and the braking torque of the retarder may be controlled based on the detected load. Similarly, the height or inclination of the load may be detected and the control may be performed only based on the state of the cargo handling device. And these controls may be applied not only to the forklift but also to the wheel loader. In this case, as the state of the cargo handling device, the state of the bucket and boom may be detected.

[0030]

[Effect of device]

 As is clear from the above description, according to the present invention, since the braking force by the retarder is varied according to the load applied to the cargo handling device and the condition of the cargo handling device, for example, the height of the load, The optimum braking force can be obtained and smooth deceleration can be performed. Therefore, there is no occurrence of load collapse or tipping due to sudden deceleration or excessive braking, and safe and comfortable braking can be obtained.

Moreover, shocks are strictly prohibited depending on the type of load, but in this case, it is sufficient to reduce the braking force so as not to apply a shock, and it becomes possible to selectively use the retarder control force depending on the load. , Can further improve the safety.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a service brake and an auxiliary brake according to an embodiment of the present invention.

FIG. 2 is a diagram showing a drive transmission system of a large forklift truck.

FIG. 3 is an electric circuit diagram of an electromagnetic retarder.

FIG. 4 is a characteristic diagram of retarder braking torque.

5A and 5B are schematic configuration diagrams of a lifting mechanism for a fork, in which FIG. 5A is a side view thereof, and FIG. 5B is a view showing a height detector mounting position.

FIG. 6 is a hydraulic circuit diagram of the cargo handling device.

[Explanation of symbols]

 9 cargo handling device 10 brake pedal 20 brake operation detector 25 retarder 30 control unit 31 retarder switch 43 fork 44 lift cylinder 45 tilt cylinder 60 load detector 61 mast tilt detector 62 height detector

Claims (3)

[Scope of utility model registration request] 1. A load detector for detecting a load applied to the cargo handling device in an industrial vehicle provided with a retarder as an auxiliary brake in a power transmission system for transmitting a driving force from an engine to a wheel, and a cargo handling device. A control unit for an auxiliary brake, comprising: a control unit that changes a braking force by the retarder according to a load. 2. A state detector for detecting a state of the cargo handling device in an industrial vehicle provided with a retarder for auxiliary brake in a power transmission system for transmitting a driving force from an engine to a wheel, An auxiliary brake control device, comprising: a control unit that varies a braking force by the retarder according to the state. 3. A load detector for detecting a load applied to the cargo handling device in an industrial vehicle provided with a retarder as an auxiliary brake in a power transmission system for transmitting a driving force from an engine to a wheel, and a cargo handling device. A control device for an auxiliary brake, comprising: a state detector that detects a state of the cargo handling device; and a control unit that changes a braking force by the retarder according to a load and a state.