JP2001116133A - Inching control device for industrial vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inching control device for an industrial vehicle capable of easily varying the settings of the correspondence between the operating value of an inching operation means and the engagement pressure of a clutch. SOLUTION: An inching pedal 24 is provided with an inching pedal sensor 26 that uses a potentiometer, the inching pedal sensor 26 outputting a detection signal which matches the amount by which the inching pedal 24 is operated. A control means 31 includes a CPU 32, a ROM 33 storing a map M, and the like, the CPU 32 consulting the map M from the value sensed by the inching pedal sensor 26, to determine the clutch pressure that matches the amount by which the inching pedal 24 is operated. The CPU 32 controls a forward clutch valve 10 and a reverse clutch valve 11 so that the forward clutch 8 or reverse clutch 9 is held at the read clutch pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inching control device for an industrial vehicle such as a forklift equipped with a transmission having a torque converter.

[0002]

2. Description of the Related Art Conventionally, forklifts are equipped with an inching device for performing inching travel. The inching device is used to bring the clutch into a half-engaged state (half-clutch state) when the forklift travels at a very low speed while performing a cargo handling operation.

An inching pedal arranged on the floor of the cab is connected to an inching valve via a wire.
The opening of the inching valve is mechanically linked with the amount of depression of the inching pedal by a wire. The inching pedal interlocks with the brake pedal when the depression amount becomes equal to or less than a predetermined value. In the stroke from the start of depressing the inching pedal to the predetermined position, the engagement pressure of the clutch is reduced to be in a half-clutch state, and in the further depressing stroke, the clutch is disengaged and the brake device operates.

[0004]

However, in the conventional inching apparatus, since the inching pedal and the inching valve are mechanically connected, if the opening degree of the inching valve is changed with respect to the amount of depression of the inching pedal, the parts are replaced. Is required and it takes time and effort.

The relationship between the opening of the inching valve and the amount of depression of the inching pedal is constant even if any external load is applied to the forklift. Therefore, for example, when the forklift is carrying a load and when it is not, there is a problem that the inching feeling differs depending on the presence or absence of the load and the load, even if the indentation amount of the inching pedal is the same.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and a first object of the present invention is to provide an industrial system capable of easily changing the setting of the correspondence between the operation amount of the inching operation means and the engagement pressure of the clutch. It is an object of the present invention to provide an inching control device for a vehicle. A second object is to achieve the first object and to always obtain the same inching feeling regardless of the state of the vehicle such as the presence or absence of a load.

[0007]

According to the first aspect of the present invention, there is provided a hydraulic forward clutch and a reverse clutch for transmitting the output of an engine to drive wheels via a torque converter. A transmission, a control valve that adjusts a connection state by increasing or decreasing a hydraulic pressure in a pressure receiving chamber of each clutch, an inching operation amount detection unit that detects an operation amount of the inching operation unit, and a control valve that responds to an operation amount of the inching operation unit. Storage means for storing data used to determine the clutch engagement pressure, and operation of the inching operation means using data stored in the storage means based on a detection signal of the inching operation amount detection means. Control means for controlling the control valve so that the clutch engagement pressure is in accordance with the amount.

According to a second aspect of the present invention, in the first aspect of the present invention, there is provided a detecting means for detecting a state of the vehicle body, wherein the control means detects the state of the vehicle when the inching operation means is operated. The control valve is controlled so that the clutch engagement pressure according to the state of the vehicle body is set in accordance with the detection signal.

According to a third aspect of the present invention, in the second aspect of the invention, the detecting means is a load detecting means for detecting a weight of a load loaded on a cargo handling device provided in the vehicle. According to the first aspect of the invention, the output of the engine is transmitted to the drive wheels by engaging one of the hydraulic clutches provided in the transmission, and the vehicle moves forward or backward. The control means reads out the clutch engagement pressure corresponding to the operation amount of the inching operation means based on the data stored in the storage means, and controls the control valve so that the clutch engagement pressure becomes the clutch engagement pressure.

According to the second aspect of the present invention, the first aspect is provided.
In addition to the operation of the invention described in the above, the detecting means is a state of the vehicle,
For example, an external load that causes a change in inching feeling is detected. Then, the control means controls the control valve based on the detection signal of the detection means so that the clutch engagement pressure is in accordance with the state of the vehicle, so that the inching feeling is almost constant regardless of the state of the vehicle. Be constant.

According to the invention described in claim 3, according to claim 2
In addition to the operation of the invention described in (1), the control means calculates the value of the clutch engagement pressure according to the operation amount of the inching operation means in consideration of the load determined from the detection signal of the load detection means. Therefore, the inching feeling is substantially constant regardless of the presence or absence of a load on the cargo handling device.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is embodied in a forklift as a torque converter vehicle will be described below with reference to FIGS.

As shown in FIG. 1, the output shaft 1 of the engine 1
a is connected to a transmission 3 having a torque converter 2;
The transmission 3 is connected via a differential 4 to an axle 6 having drive wheels 5.
It is connected to. The engine 1 is provided with an engine throttle actuator (hereinafter simply referred to as a throttle actuator) 7, and the throttle opening is adjusted by the operation of the throttle actuator 7, so that the rotation speed of the engine 1, that is, the rotation speed of the output shaft 1a of the engine 1, is reduced. Adjusted.

The transmission 3 has an input shaft (main shaft) 3a.
And an output shaft (counter shaft) 3b.
a is provided with a forward clutch 8 and a reverse clutch 9. A gear train (not shown) is provided between the forward clutch 8 and the reverse clutch 9 and the output shaft 3b, and the rotation of the input shaft 3a is transmitted to the output shaft 3b via the clutches 8, 9 and the gear train. Is transmitted. A hydraulic clutch, a wet multi-plate clutch in this embodiment, is used for both clutches 8 and 9, and the connection force can be adjusted by the oil pressure in the pressure receiving chambers 8a and 9a, and the oil in the pressure receiving chambers 8a and 9a can be adjusted. The connection force is configured to increase as the pressure is increased. The hydraulic pressure in the pressure receiving chambers 8a and 9a of the forward clutch 8 and the reverse clutch 9 is controlled by hydraulic pressure supplied via a forward clutch valve 10 and a reverse clutch valve 11 as control valves. Forward clutch valve 10 and reverse clutch valve 1
Reference numeral 1 denotes a proportional solenoid valve having an opening proportional to the amount of current supplied to the solenoid.

A parking brake 1 is provided on an output shaft 3b of the transmission 3.
2, the parking brake 12 includes a disk 12a and a brake pad 12b. Brake pad 1
2b is urged in the direction of being pressed against the disk 12a by the spring force of a spring (not shown) to generate an engagement pressure (clutch pressure) for braking, and is supplied to the pressure receiving chamber 12c via the brake valve 13. The brake state is released by hydraulic pressure. An electromagnetic valve is used as the brake valve 13.

Although FIG. 1 shows the torque converter 2, the transmission 3, and the valves 10, 11, and 13 independently, these devices are incorporated in one housing to constitute an automatic transmission. I have. A hydraulic pump (not shown) is incorporated in the transmission 3, and the discharge oil of the hydraulic pump is supplied to each of the pressure receiving chambers 8 a and 9 through a flow path (not shown) and each of the valves 10, 11 and 13.
a, 12c. The hydraulic pump is driven by a rotational force transmitted to the transmission 3 when the engine 1 rotates.

A gear 14 is provided on the input shaft 3a of the transmission 3 so as to be integrally rotatable, and a rotation speed of the input shaft 3a is detected by a turbine speed sensor 15 comprising a magnetic pickup. The turbine speed sensor 15 outputs a pulse signal proportional to the speed of the input shaft 3a. Output shaft 3 of transmission 3
A gear 16 is provided rotatably with b, and the speed of the output shaft 3b is detected by a vehicle speed sensor 17 composed of a magnetic pickup. The vehicle speed sensor 17 outputs a pulse signal proportional to the rotation speed of the output shaft 3b.

Hydraulic pump 1 driven by engine 1
On the discharge side of 8, a lift cylinder 20 for raising and lowering a fork 19 as a cargo handling device via a conduit or the like (not shown) and a tilt cylinder (not shown) for tilting a mast 21
Is connected. Fork 1 in lift cylinder 20
9 is provided with a pressure sensor 22 as a load detecting means for detecting the loaded load. The pressure sensor 22 detects the oil pressure inside the lift cylinder 20 and outputs a detection signal corresponding to the load of the fork 19.

An accelerator pedal 23, an inching pedal 24 as inching operation means, and a brake pedal 25 are provided on the floor of the cab. The inching pedal 24 is used to bring the clutch into a half-engaged state (half-clutch state) when the forklift travels at a very low speed while performing a cargo handling operation. When the brake pedal 25 is operated (depressed), the brake pedal 25 operates independently of the inching pedal 24. However, when the inching pedal 24 is operated (depressed), the inching pedal 24 and the brake pedal 2 are operated halfway.
5 can be interlocked.

The inching pedal 24 is provided with an inching pedal sensor 26 as an inching operation amount detecting means, and the depression amount (pedal stroke) of the inching pedal 24 is detected by the inching pedal sensor 26. The inching pedal sensor 26 is composed of a potentiometer and outputs a current value corresponding to the pedal stroke of the inching pedal 24.

A shift lever (forward-reverse lever) 27 and a cargo handling lever 28 are provided at the front of the cab. The shift switch 29 that detects the position of the shift lever 27
It detects whether the shift lever 27 is in any of the forward position F, the reverse position R, and the neutral position (neutral position) N,
A signal corresponding to each position is output. The cargo handling lever 28 is provided with a cargo handling lever sensor 30, and the cargo handling lever sensor 3
0 outputs a detection signal corresponding to the operation amount of the cargo handling lever 28.

Next, an electrical configuration for controlling the actuator and each clutch will be described. The control device 31 as a control means includes a central processing unit (hereinafter referred to as a CPU) 3.
2. Read-only memory (ROM) as storage means 3.
3. Readable and rewritable memory (RAM) 34, input interface 35 and output interface 36
It has. The ROM 33 stores a predetermined control program and various data required for executing the control program. The calculation result of the CPU 32 is temporarily stored in the RAM 34. The CPU 32 operates based on a control program stored in the ROM 33.

Engine speed sensor 15, vehicle speed sensor 1
7 is connected to the CPU 32 via the input interface 35. The inching pedal sensor 26, the cargo handling lever sensor 30, and the pressure sensor 22 are A / Ds (not shown).
CPU 3 via converter and input interface 35
2 are connected.

The CPU 32 controls the throttle actuator 7, the forward clutch valve 10, the reverse clutch valve 1 via an output interface 36 and a drive circuit (not shown).
1 and the brake valve 13.

The ROM 33 stores a map M shown in FIG. 2 showing a relationship between a clutch stroke pressure (hereinafter referred to as a clutch pressure) and a pedal stroke of the inching pedal 24. The map M in FIG. 2 is a map M when the shift lever 27 is in the forward position, and the F line is the clutch pressure of the forward clutch 8 and the R line is the clutch pressure of the reverse clutch 9. As shown in FIG. 2, the pedal stroke is an inching region from a state where the pedal stroke is zero to a predetermined stroke, and a brake region if the pedal stroke is longer than that. In the brake area, the forward clutch 8 and the reverse clutch 9 are simultaneously engaged to obtain a braking force. A plurality of maps M are stored according to the load, and a map M corresponding to a detection signal from the pressure sensor 22 is used as appropriate. In FIG. 2, a plurality of maps for each load are drawn on the same map graph for convenience.

The inching pedal sensor 26 detects the amount of depression after the inching pedal 24 loses its play, and in a state where the amount of depression of the inching pedal 24 is not detected, the forward clutch 8 applies the fully engaged clutch pressure Pc ( FIG. 2). In the case of an empty load (no load) in which no load is placed on the fork 19, the clutch pressure of the forward clutch 8 in the inching region is determined based on a map line Fo indicated by a broken line, and a maximum load (full load).
Is determined based on the map line Fn indicated by the solid line.
Between the map lines Fo and Fn of the no load and the full load, the inching pedal 24
A plurality of map lines Fk (k = 1, 2,..., N-1) (only one shown by a dashed line in FIG. 3) is set so that the setting of the clutch pressure with respect to the stepping amount of the vehicle becomes large.
The relationship between the clutch pressure and the command current value commanded by the CPU 32 is in a negative proportion that the clutch pressure decreases as the current value increases. The ROM 33 also stores a map M when the shift lever is at the reverse position. However, since only the reverse clutch is engaged in the inching area, Fo ... Fn is replaced by Ro ... Rn in FIG. The R line is replaced by the F line so that it becomes a line. Also, map M
Alternatively, a relational expression between the pedal stroke of the inching pedal 24 and the clutch pressure may be stored.

The ROM 33 stores a correction coefficient α (W) for correcting the clutch pressure determined for the stroke of the inching pedal 24 in the brake area in accordance with the load W. The correction coefficient α (W) is set to a value that increases as the value of the load W increases. The CPU 32 receives the output signals of the sensors 15, 17, 22, 26, and 30 and operates according to various control programs stored in the ROM 33 to send control command signals to the throttle actuator 7 and the valves 10, 11, and 13. Output.

Next, the operation of the inching device configured as described above will be described. In a cargo handling operation in which the forklift performs a cargo handling operation while traveling at a low speed (in this case, the forward movement), the inching pedal 24 is used to maintain the low speed state.
To put the forward clutch 8 in the half-clutch state. At this time, the CPU 32 detects whether the depression stroke of the inching pedal 24 is in the inching area or the braking area based on the detection signal from the inching pedal sensor 26. The CPU 32 recognizes the load W based on a detection signal from the pressure sensor 22. When it is in the inching area, the CPU 32 reads map data having a map line corresponding to the load W from the ROM 33.
For example, the map line Fo is adopted when there is no load, and the map line Fn is adopted when it is full load. If the load W is between no load and full load, the map lines F1, F2,
, Fn-1 are adopted. And CP
U32 refers to the previously read map line from the inching pedal stroke determined based on the detection signal from the inching pedal sensor 26, and increases the clutch pressure.

Then, the CPU 32 commands a current value corresponding to the clutch pressure. As a result, the forward clutch valve 10
Is hydraulically controlled, and the forward clutch 8 is set to a value corresponding to the depression stroke of the inching pedal 24 determined by the map line.
Is controlled. At this time, the CPU 32 controls the reverse clutch valve 11 so that the clutch pressure of the reverse clutch 9 becomes zero. As a result, the inching feeling is substantially constant regardless of the presence or absence of a load on the fork 19 and the magnitude of the load.

When the inching pedal 24 is depressed, the inching area is switched to the braking area at a predetermined position, and the brake device operates. First, in the inching region, the clutch pressure of the forward clutch 8 decreases as the inching pedal 24 is depressed, and the forward clutch 8 is completely disengaged at a switching point where the inching region is switched to the braking region. After this switching point is a brake region in which the brake device operates. In this brake region, the CPU 32 refers to the map M and determines the clutches 8, 9 according to the inching pedal stroke determined based on the detection signal from the inching pedal sensor 26. Of each clutch is obtained. At this time, the forward clutch 8 and the reverse clutch 9 have the FR simultaneous engagement pressure corresponding to the inching pedal stroke. The CPU 32 controls the forward clutch valve 10 and the reverse clutch valve 11 so that the front and rear clutch pressures of the forward clutch 8 and the reverse clutch 9 increase by the same value.
Control. Such simultaneous engagement of the forward clutch 8 and the reverse clutch 9 functions as a brake.

At this time, the CPU 32 performs a correction so as to obtain a clutch pressure corresponding to the load by multiplying the simultaneous engagement clutch pressure of the forward clutch and the reverse clutch read by the map M by a correction coefficient α (W). By correcting the clutch pressure, the simultaneous engagement clutch pressure increases as the load increases, and as a result, the brake feeling becomes substantially constant regardless of the presence or absence of a load and the magnitude of the load. In addition,
When the vehicle moves in reverse, it operates in the same manner, except that the front and rear are reversed.

Therefore, in this embodiment, the following effects can be obtained. (1) Since the relationship between the pedal stroke and each clutch pressure when the inching pedal 24 is depressed is determined by the map M stored in the ROM 33, it is easily changed to a different setting only by changing the data of the map M stored in the ROM 33. Can be changed.

(2) The clutch pressure for the pedal stroke of the inching pedal 24 read from the map M is a clutch pressure corresponding to the load. As a result, an almost constant inching feeling can be obtained at any time, regardless of the presence or absence of a load and the difference in the load.

(3) Since the forward clutch 8 and the reverse clutch 9 are simultaneously engaged to provide a function as a brake device, a normal brake such as a drum brake can be eliminated, and the structure of the forklift can be simplified. .

(4) Forward clutch 8 in brake area
Since the simultaneous engagement clutch pressure of the reverse clutch 9 is corrected according to the load W, the brake feeling can be made substantially constant.

The embodiment is not limited to the above, and may be modified, for example, as follows. The detection means for detecting the state of the vehicle body is not limited to the pressure sensor 22 for detecting the load, and may be a sensor for indirectly detecting an external load other than the load, for example, running resistance or the air pressure of the driving wheels 5. . In short, what is necessary is just to detect the state of the vehicle which causes the change of the inching feeling.

Although the clutch pressure with respect to the pedal stroke of the inching pedal 24 is a value considering the load W in the inching region, the load W need not be considered. Further, the correction based on the load is also performed in the brake area, but the correction may not be performed.

The configuration is not limited to a configuration in which the inching pedal 24 and the brake pedal 25 can be interlocked.
For example, the brake device that operates when the inching pedal 24 is operated may be a brake by simultaneous engagement of the two clutches 8 and 9, and the service brake may be operated when the brake pedal 25 is operated.

The brake device in the brake area when the inching pedal 24 is depressed is a two clutch 8,
The brake is not limited to the one using the simultaneous engagement of the brakes 9, but may be a regular brake such as a drum brake. At least, if the clutch pressure for the pedal stroke in the inching region is determined from the map M to a value in consideration of the load, the inching feeling can be made substantially constant regardless of the presence or absence of the load and the difference in the load.

The brake device is not limited to a brake device in which the forward clutch 8 and the reverse clutch 9 are simultaneously engaged. For example, the parking brake 12 provided in the transmission 3 may be operated. When the brake switch 25a provided on the brake pedal 25 is input for a predetermined time or longer, the state in which the parking brake 12 operates the brake is maintained. In this way, the parking lever is not required, and the parking brake 12 is effective even when the foot is released from the brake pedal 25, so that there is no need to continue to step on the brake pedal 25.

The detecting means is not limited to the load detecting means. For example, the engine speed sensor 15 and the vehicle speed sensor 1
The slip of the clutches 8 and 9 is detected based on the detected values of 7, and the target clutch pressure is determined by estimating the clutch pressure from the detected values. Then, the CP is set so as to reach the target clutch pressure.
U32 may control the clutch valve.

The storage means is not limited to the ROM 33. For example, it may be an EEPROM or a RAM having a backup battery. This makes it easy to rewrite data.

The map M is not limited to a straight line but may be a curved line. ○ The inching pedal operation amount detecting means is not limited to the potentiometer as the inching pedal sensor 26,
Any sensor that can detect the pedal stroke of the inching pedal 24 may be used.

The inching pedal 24 is not limited to the inching area from the start of stepping on to the predetermined position, and to the braking area thereafter. That is, the clutch 8 and 9 may be completely disengaged when there is no brake area and the inching pedal 24 is fully depressed.

In the map M indicating the relationship between the inching pedal stroke and the clutch pressure, the clutch pressure may be set to be high when the vehicle is not loaded and to be low when the vehicle is fully loaded.

The relationship between the clutch pressure and the command current value is not negatively proportional, but may be positively proportional as the clutch pressure increases as the current value increases. The cargo handling device is not limited to the fork 19 and may be an attachment for a roll clamp or the like.

For example, a setting change volume (or switch) 50 as shown in FIG. 5 may be provided in the driver's seat or the like, and the setting of the clutch pressure with respect to the pedal stroke may be changed by the volume 50. In this way, the inching feeling can be changed according to the driver's preference. The setting operation means is constituted by a setting change volume.

The technical ideas other than the claims that can be grasped from the above embodiment and other examples will be described below together with their effects. (1) According to claim 1, in the data stored in the storage means, a plurality of set data of a clutch engagement pressure with respect to an operation amount of the inching operation means is set, and one of the plurality of data is selected. The control means selects setting data according to a detection value of the data selecting means, and controls the control valve based on the setting data. In this case, a suitable or desired inching feeling can be obtained by a plurality of setting data. The data selecting means is a concept including the detecting means according to the second aspect.

(2) In the technical idea (1), the data selection means is a setting operation means (50) for manually setting a clutch engagement pressure with respect to an operation amount of an inching operation means from a plurality of stages. is there. In this case, for example, a driver's favorite inching feeling can be obtained.

(3) In claim 3, the control means controls the clutch engagement pressure to decrease as the load increases in accordance with the detection signal of the load detection means.

[0051]

As described in detail above, according to the first aspect of the present invention, the inching device is electronically controlled, and the value of the clutch pressure with respect to the amount of depression of the inching pedal can be easily changed by changing the data in the storage means. Can be changed to

According to the invention described in claim 2, according to claim 1
In addition to the effects of the invention described in (1), since the clutch engagement pressure with respect to the operation amount of the inching operation means changes according to the state of the vehicle, the inching feeling can be made substantially constant in any vehicle state.

According to the invention of claim 3, according to claim 1,
Or, in addition to the effect of the invention described in claim 2, since the clutch engagement pressure with respect to the operation amount of the inching operation means changes in accordance with the load of the load on the cargo handling equipment, the inching operation is performed regardless of the presence or absence of the load and the difference in the load. Feeling can be almost constant.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a forklift according to an embodiment.

FIG. 2 is a map showing a relationship between a pedal stroke and a clutch pressure.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Engine, 2 ... Torque converter, 3 ... Transmission, 5
... drive wheel, 8 ... forward clutch, 8a ... pressure receiving chamber, 9 ... reverse clutch, 9a ... pressure receiving chamber, 10 ... forward clutch valve as control valve, 11 ... reverse clutch valve as control valve, 19 ... as cargo handling equipment A fork, 22... A pressure sensor serving as load detecting means and constituting a detecting means;
24 ... an inching pedal as an inching operation means,
26 ... inching pedal sensor as inching operation amount detecting means, 31 ... control device as control means, 33 ...
ROM as storage means.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI theme coat ゛ (reference) F16H 63:12 F16H 63:12 F term (reference) 3D041 AA38 AB07 AC08 AC16 AD00 AD02 AD31 AD51 AE28 AE39 3G093 AA04 AA08 AA14 DA01 DB00 DB01 DB05 DB07 DB11 EA03 EB03 FA10 3J052 AA02 FB02 FB31 FB41 GC61 GC62 GC74 KA02 LA07

Claims (3)

[Claims] 1. A transmission having a hydraulic forward clutch and a reverse clutch for transmitting the output of an engine to drive wheels via a torque converter, and adjusting the connection by increasing or decreasing the oil pressure in a pressure receiving chamber of each clutch. A control valve to perform, an inching operation amount detecting means for detecting an operation amount of the inching operation means, and a storage means for storing data used for obtaining a clutch engagement pressure corresponding to the operation amount of the inching operation means, Based on the detection signal of the inching operation amount detection means,
An inching control device for an industrial vehicle, comprising: control means for controlling the control valve so as to obtain a clutch engagement pressure corresponding to an operation amount of the inching operation means using data stored in the storage means. 2. A detecting means for detecting a state of a vehicle body, wherein the control means sets a clutch engagement pressure according to a state of the vehicle body according to a detection signal of the detecting means when the inching operation means is operated. The inching control device for an industrial vehicle according to claim 1, wherein the control valve is controlled as described above. 3. The inching control device for an industrial vehicle according to claim 2, wherein said detecting means is a load detecting means for detecting a weight of a load loaded on a cargo handling device provided on the vehicle.