JP2013249892A - Control device of industrial vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress overheat and initial stage wear of clutch of an industrial vehicle.SOLUTION: A control device of an industrial vehicle 100 transmitting output torque of an internal combustion engine 1 transmitted via a torque converter 21 to wheels 4 via hydraulic clutches 221, 222 has an inching control means 6 controlling supplying hydraulic pressure to the hydraulic clutches 221, 222 according to the operating quantity of an inching pedal 54 and controlling brake liquid pressure supplied to a braking device 3 arranged in the wheels 4 and is characterized in that the inching control means 6 lowers the supplied hydraulic pressure to the hydraulic clutches 221, 222 to a predetermined releasing hydraulic pressure at which the hydraulic clutches 221, 222 are released in the case the brake liquid pressure becomes not less than a predetermined brake operation liquid pressure when controlling the hydraulic clutches 221, 222 in a half-clutch condition.

Description

  The present invention relates to an industrial vehicle control apparatus.

  As a conventional industrial vehicle control apparatus, there is an apparatus that includes an inching pedal and controls the hydraulic pressure supplied to the clutch and the brake hydraulic pressure in accordance with the depression amount of the inching pedal.

JP 2009-154987 A

  However, the conventional industrial vehicle control device described above does not take into account the change in brake hydraulic pressure characteristics. For this reason, there is a problem that the brake is operated when the clutch is in the half-clutch state due to a change in the brake hydraulic pressure characteristics, and overheating due to heat generation of the clutch occurs or the clutch wears out early.

  The present invention has been made paying attention to such problems, and an object thereof is to suppress the occurrence of overheating due to heat generation of the clutch and early wear of the clutch.

  The present invention is a control device for an industrial vehicle that transmits an output torque of an internal combustion engine transmitted through a torque converter to wheels through a hydraulic clutch, and is applied to the hydraulic clutch according to an operation amount of an inching pedal. Inching control means for controlling supply hydraulic pressure and controlling brake hydraulic pressure supplied to a braking device provided on the wheel is provided. Then, the inching control means releases the hydraulic pressure supplied to the hydraulic clutch when the hydraulic pressure exceeds the predetermined hydraulic pressure when the hydraulic clutch is controlled to the half-clutch state. It is characterized in that it is lowered to a predetermined release hydraulic pressure to be in a state.

  According to the present invention, when the brake hydraulic pressure becomes equal to or higher than the brake hydraulic pressure, the hydraulic clutch is released, so that the brake does not operate with the hydraulic clutch in a half-clutch state. Therefore, the driving force by the hydraulic clutch and the braking force by the brake do not act at the same time, and the occurrence of overheating due to heat generation of the clutch and the early wear of the clutch can be suppressed.

1 is a schematic view of a forklift according to a first embodiment of the present invention. It is the figure which showed the change characteristic of the hydraulic pressure supplied to the fastening clutch with respect to the inching operation amount, and the change characteristic of the brake fluid pressure with respect to the inching operation amount. It is a figure explaining the supply hydraulic pressure control by 1st Embodiment of this invention. It is the schematic of the forklift by 2nd Embodiment of this invention. It is the figure which showed the change characteristic of the supply hydraulic pressure to a fastening clutch when a shock generation switch is turned ON.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a schematic view of a forklift 100 according to a first embodiment of the present invention.

  The forklift 100 according to the first embodiment of the present invention includes a drive system 2, a braking device 3, and a travel operated by a driver if the engine 1 is composed of a plurality of parts for transmitting the output of the engine 1 to the wheels 4. A lever 51, an accelerator pedal 52, a brake pedal 53, an inching pedal 54, and a controller 6 that controls each component of the engine 1 and the drive system 2 are provided.

  The engine 1 generates power necessary for traveling and cargo handling work of the forklift 100.

  The drive system 2 includes a torque converter 21, a transmission 22, a propeller shaft 23, a final reduction differential device 24, and a drive shaft 25.

  The torque converter 21 transmits the power of the engine 1 to the transmission 22 via a fluid.

  The transmission 22 automatically switches the gear stage to the gear stage selected by the driver, and outputs the power of the engine 1 transmitted through the torque converter 21 by increasing / decreasing it according to the selected gear stage. .

  Inside the transmission 22, a wet multi-plate forward clutch 221 whose torque capacity is continuously changed by the forward solenoid valve 7 and a wet multi-plate whose torque capacity is continuously changed by the reverse solenoid valve 8. A reverse clutch 222 is provided. The torque capacity is an upper limit torque that can be transmitted by the forward clutch 221 and the reverse clutch 222. The forward clutch 221 and the reverse clutch 222 are controlled to three states of an engaged state, a half-clutch state (slip state), and a released state by changing the torque capacity. By engaging the forward clutch 221, the forklift 100 can travel forward, and by engaging the reverse clutch 222, the forklift 100 can travel backward.

  The forward solenoid valve 7 adjusts the hydraulic pressure of the hydraulic oil supplied from the oil pump 9 driven using a part of the power of the engine 1 to a desired hydraulic pressure and supplies the hydraulic oil to the forward clutch 221. By controlling the hydraulic pressure supplied to the forward clutch 221 by the forward solenoid valve 7, the torque capacity of the forward clutch 221 is controlled.

  The reverse solenoid valve 8 adjusts the hydraulic pressure of the hydraulic oil supplied from the oil pump 9 driven using a part of the power of the engine 1 to a desired hydraulic pressure and supplies the hydraulic oil to the reverse clutch 222. By controlling the hydraulic pressure supplied to the reverse clutch 222 by the reverse solenoid valve 8, the torque capacity of the reverse clutch 222 is controlled.

  The propeller shaft 23 connects the output shaft of the transmission 22 and the input shaft of the final reduction differential 24.

  The final reduction gear differential 24 integrates the final reduction gear and the differential gear, and transmits the rotation to the left and right drive shafts 25 after decelerating the rotation of the propeller shaft 23. Further, when it is necessary to create a speed difference between the rotational speeds of the left and right drive shafts 25 such as during a curve run, the speed difference is automatically given to enable smooth running. Wheels 4 are attached to the ends of the left and right drive shafts 25, respectively.

  The braking device 3 includes a brake booster 31, a master cylinder 32, a drum brake 33, and a brake fluid pressure sensor 34.

  The brake booster 31 is connected to the brake pedal 53 and reduces the force required to operate the brake pedal 53 using the suction negative pressure of the engine 1.

  The master cylinder 32 generates a hydraulic pressure (hereinafter referred to as “brake hydraulic pressure”) for operating the drum brake 33 in accordance with the depression amount of the brake pedal 53 (hereinafter referred to as “brake operation amount”). The brake fluid pressure increases as the brake operation amount increases.

  The drum brake 33 reduces the rotational speed of the wheel 4 by pressing a brake shoe with a friction material attached to the drum that rotates together with the wheel 4 to generate a braking force. As the brake hydraulic pressure supplied from the master cylinder 32 to the drum brake 33 increases, the pressing force of the brake shoe increases, so that the braking force of the forklift 100 increases.

  The brake hydraulic pressure sensor 34 detects the brake hydraulic pressure supplied from the master cylinder 32 to the drum brake 33.

  The travel lever 51 is a lever that selects the traveling direction of the forklift 100. When the travel lever 51 is switched to the forward position, the forward clutch 221 is engaged and the reverse clutch 222 is released. On the other hand, when the traveling lever 51 is switched to the reverse position, the forward clutch 221 is disengaged and the reverse clutch 222 is engaged. Further, when the traveling lever 51 is switched to the neutral position, the forward clutch 221 and the reverse clutch 222 are released. The travel lever 51 is provided with a lever position detection sensor 511 that detects the position of the travel lever 51.

  The accelerator pedal 52 is a pedal that adjusts the engine output. The accelerator pedal 52 is provided with an accelerator stroke sensor 521 that detects the amount of depression of the accelerator pedal 52 (hereinafter referred to as “accelerator operation amount”).

  The brake pedal 53 is a pedal that adjusts the braking force of the forklift 100.

  The inching pedal 54 is a pedal that adjusts the torque capacity of the clutch being engaged (hereinafter referred to as “engaged clutch”) among the forward clutch 221 and the reverse clutch 222. The inching pedal 54 is provided with an inching stroke sensor 541 that detects a depression amount of the inching pedal 54 (hereinafter referred to as “inching operation amount”).

  The inching pedal 54 is mechanically connected to the brake pedal 53. When the inching pedal 54 is depressed more than a predetermined operation amount, the brake pedal 53 is automatically depressed in conjunction with the inching pedal 54. ing.

  That is, when the inching pedal 54 is depressed, the hydraulic pressure supplied to the engagement clutch (the forward clutch 221 or the reverse clutch 222) is controlled according to the inching operation amount, and the engagement clutch is in three states: an engaged state, a half clutch state, and a released state The brake fluid pressure is changed according to the inching operation amount, and a braking force according to the brake fluid pressure is generated. The relationship between the inching operation amount, the hydraulic pressure supplied to the engagement clutch, and the brake hydraulic pressure will be described later with reference to FIG.

  The controller 6 is composed of a microcomputer having a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM), and an input / output interface (I / O interface). In addition to the brake fluid pressure sensor 34, lever position detection sensor 511, accelerator stroke sensor 521, and inching stroke sensor 541, signals from various sensors necessary for controlling the forklift 100 are input to the controller 6. The

  The controller 6 controls the engine output according to the accelerator operation amount.

  Further, the controller 6 controls the forward solenoid valve 7 and the reverse solenoid valve 8 in accordance with the position of the travel lever 51 and the inching operation amount, and controls the hydraulic pressure supplied to the forward clutch 221 and the reverse clutch 222. As a result, the torque capacities of the forward clutch 221 and the reverse clutch 222 are controlled, and the forward clutch 221 and the reverse clutch 222 are controlled in three states: an engaged state, a half-clutch state (slip state), and a released state.

  FIG. 2 is a diagram illustrating a change characteristic of the hydraulic pressure supplied to the engagement clutch (forward clutch 221 or reverse clutch 222) with respect to the inching operation amount, and a change characteristic of the brake hydraulic pressure with respect to the inching operation amount.

  First, the change characteristic of the hydraulic pressure supplied to the engagement clutch with respect to the inching operation amount will be described.

  As shown in FIG. 2, when the inching operation amount is less than the second operation amount, the hydraulic pressure supplied to the engagement clutch is maintained at a predetermined engagement hydraulic pressure even when the inching pedal 54 is depressed. The engagement hydraulic pressure is a hydraulic pressure necessary for bringing the forward clutch 221 and the reverse clutch 222 into an engaged state.

  When the inching operation amount becomes the second operation amount, the hydraulic pressure supplied to the engagement clutch is decreased from the engagement hydraulic pressure toward the predetermined slip hydraulic pressure, and thereafter the engagement clutch when the inching operation amount becomes the third operation amount. The hydraulic pressure supplied to the engagement clutch is gradually reduced as the inching operation amount increases so that the hydraulic pressure supplied to the engine becomes a predetermined release hydraulic pressure. The engagement clutch is in a half-clutch state when the supply hydraulic pressure is equal to or lower than the slip hydraulic pressure, and is in a released state when the supply hydraulic pressure is equal to or lower than the release hydraulic pressure.

  In this manner, the supply hydraulic pressure is controlled so that the engagement clutch is engaged until the inching operation amount reaches the second operation amount. When the inching operation amount is from the second operation amount to the third operation amount, the supply hydraulic pressure is controlled so that the engagement clutch is in the half-clutch state. When the inching operation amount is equal to or greater than the third operation amount, the supply hydraulic pressure is controlled so that the engagement clutch is released.

  Next, the change characteristic of the brake fluid pressure with respect to the inching operation amount will be described.

  As shown in FIG. 2, when the inching operation amount becomes equal to or larger than the first operation amount, the brake pedal 53 starts to be depressed automatically in conjunction with the inching pedal 54, and gradually increases as the inching operation amount increases. Will increase. When the brake fluid pressure becomes equal to or higher than a predetermined brake operation fluid pressure, a braking force by the drum brake 33 is generated.

  Here, in an initial state such as when the forklift 100 is delivered, the change characteristic of the brake fluid pressure so that the brake fluid pressure becomes equal to or higher than the brake operation fluid pressure after at least the inching operation amount becomes larger than the third operation amount. Is set. That is, the brake fluid pressure increases in accordance with the inching operation amount so that the braking force is generated after the engagement clutch is released.

  Thus, between the third operation amount and the inching operation amount at which the brake fluid pressure becomes the brake operation fluid pressure (hereinafter referred to as “brake operation operation amount”), the brake operation operation is performed more than the third operation amount. I want to make sure that the underlap is secured so that the amount is always large. The underlap margin is a region where the driving force and the braking force are not generated at the same time and do not overlap each other.

  However, since the change characteristic of the brake fluid pressure is likely to change with time, and the individual variation is large, the brake fluid pressure becomes equal to or higher than the brake operation fluid pressure before the inching operation amount becomes the third operation amount. Sometimes. That is, when the fastening clutch is in the half clutch state, the braking force by the drum brake 33 may be generated.

  The inching pedal 54 is a pedal that is used when adjusting the speed of the forklift 100 while performing a cargo handling operation. Therefore, if a braking force is generated when the engagement clutch is in a half-clutch state, friction between the engagement clutch and the brake shoe will occur. The wear of the material is promoted, the fastening clutch generates heat and overheats, and the durability of the forklift 100 is also deteriorated.

  Therefore, in the present embodiment, the hydraulic pressure supplied to the engagement clutch is controlled according to the inching operation amount and the brake hydraulic pressure. Hereinafter, the supply hydraulic pressure control will be described with reference to FIG.

  FIG. 3 is a diagram for explaining supply hydraulic pressure control according to the present embodiment.

  As shown in FIG. 3, when the brake fluid pressure reaches the brake actuation fluid pressure before the inching operation amount becomes the third operation amount, the hydraulic pressure supplied to the engagement clutch is reduced to the release hydraulic pressure at that time.

  As a result, the braking force can be generated after the engagement clutch is released regardless of the change in the increase characteristic of the brake fluid pressure. Therefore, deterioration of the operability and durability of the forklift 100 described above can be suppressed.

(Second Embodiment)
Next, a second embodiment of the present invention will be described. This embodiment is different from the first embodiment in that the change characteristic of the hydraulic pressure supplied to the engagement clutch can be changed as necessary. Hereinafter, the difference will be mainly described. In each of the following embodiments, the same reference numerals are used for portions that perform the same functions as those of the first embodiment described above, and repeated descriptions are omitted as appropriate.

  FIG. 4 is a schematic view of a forklift 100 according to the second embodiment of the present invention.

  When working on the forklift 100, it may be necessary to start with a shock in order to get over obstacles such as wood, debris, and grooves. Therefore, the forklift 100 according to the second embodiment of the present invention further includes a shock generation switch 55 in order to enable starting with a shock.

  The shock generation switch 55 is a switch operated by the driver. The ON / OFF signal of the shock generation switch 55 is input to the controller 6. By turning on the shock generation switch 55, the change characteristic of the hydraulic pressure supplied to the forward clutch 221 or the reverse clutch 222 when the inching pedal is operated changes as shown in FIG.

  FIG. 5 is a diagram showing a change characteristic of the hydraulic pressure supplied to the engagement clutch when the shock generation switch 55 is turned on.

  As shown in FIG. 5, when the shock generation switch 55 is turned ON, the hydraulic pressure supplied to the engagement clutch changes stepwise from the engagement hydraulic pressure to zero when the inching operation amount becomes the second operation amount. Thus, the change characteristic of the hydraulic pressure supplied to the engagement clutch is changed.

  Accordingly, by returning the inching pedal 54 from a state where the inching pedal 54 is depressed by the second operation amount or more, the engaged clutch in the released state can be brought into the engaged state all at once, so that it is possible to start with a shock.

  Note that the present invention is not limited to the above-described embodiment, and it is obvious that various modifications can be made within the scope of the technical idea.

  For example, in the above embodiment, a forklift has been described as an example of an industrial vehicle, but the present invention may be applied to an industrial vehicle other than a forklift. Further, although the drum brake 33 is used as the braking device 3, a disc brake may be used.

  In the second embodiment, when the inching operation amount becomes the second operation amount, the hydraulic pressure supplied to the engagement clutch is set to zero. However, the control may be performed so that it is at least equal to or less than the release hydraulic pressure.

1 engine (internal combustion engine)
5 Controller (Inching control means)
21 Torque Converter 54 Inching Pedal 55 Shock Generation Switch 100 Forklift (Industrial Vehicle)
221 Forward clutch (hydraulic clutch)
222 Reverse clutch (hydraulic clutch)

Claims (2)

An industrial vehicle control device for transmitting output torque of an internal combustion engine transmitted through a torque converter to wheels through a hydraulic clutch,
Inching control means for controlling the hydraulic pressure supplied to the hydraulic clutch according to the operation amount of the inching pedal and the brake hydraulic pressure supplied to the braking device provided on the wheel,
The inching control means includes
When the hydraulic clutch is controlled to a half-clutch state, if the brake hydraulic pressure becomes equal to or higher than a predetermined brake hydraulic pressure, the hydraulic pressure supplied to the hydraulic clutch is set to a predetermined level at which the hydraulic clutch is released. Lower to release hydraulic pressure,
An industrial vehicle control device. A shock generation switch,
The inching control means includes
When the shock generation switch is ON, when the operation amount of the inching pedal exceeds a predetermined operation amount, the hydraulic pressure supplied to the hydraulic clutch is set to a predetermined engagement at which the hydraulic clutch is engaged. Reducing the hydraulic pressure to a hydraulic pressure below the release hydraulic pressure,
The industrial vehicle control device according to claim 1.

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