JP4113997B2 - Industrial vehicle inching control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an inching control device equipped in an industrial vehicle having a torque converter between an engine and a forward / reverse clutch.
[0002]
[Prior art]
Conventionally, a forklift as an industrial vehicle has an inching device. The forklift transmission is provided with a forward clutch and a reverse clutch. The inching device is used for causing the vehicle to travel at a low speed during a cargo handling operation or the like by depressing the inching pedal and adjusting the clutch on the connection side to a half-clutch state.
[0003]
The forklift has a brake pedal in addition to the inching pedal, and when the brake pedal is depressed, a service brake such as a drum brake arranged on the driving wheel works. The inching pedal is configured to be interlocked with the brake pedal when the amount of depression is after a predetermined position. When the inching pedal is depressed, an inching region where inching operation can be performed from the start of the stepping to a predetermined position becomes an inching region, and when the inching pedal is depressed thereafter, a braking region interlocked with the brake pedal is obtained.
[0004]
[Problems to be solved by the invention]
By the way, since a forklift is used for the work of carrying a load, a brake is frequently used every time the cargo is picked up or loaded. In addition, an inching pedal brake is also used during cargo handling work. As described above, in a forklift that frequently uses a brake, parts of a brake device such as a drum brake are relatively consumed. In particular, in a drum brake or the like that obtains a braking force by frictional wear of parts such as a brake lining, there is a problem that it takes time and cost to perform maintenance and replacement of the brake device.
[0005]
The present invention has been made in view of the above-mentioned problems, and a first object is to use a clutch as a brake device at least when an inching pedal is operated, so that maintenance frequency such as replacement of parts of the brake device is maintained. It is an object of the present invention to provide an inching control device for an industrial vehicle that can reduce the amount of noise. The second object achieves the first object, and by using the forward / reverse clutch as a brake, it is not necessary to newly install a brake device, and the structure can be simplified.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, according to the first aspect of the present invention, in an industrial vehicle equipped with a transmission having a hydraulic forward clutch and a reverse clutch that transmits the output of an engine to a drive wheel via a torque converter, A control valve that adjusts the connection state by increasing / decreasing the oil pressure in the pressure receiving chamber of each clutch; a clutch-type brake means provided on a drive transmission shaft between the torque converter and the drive wheel; and the brake means A brake control valve that adjusts the connection state by increasing / decreasing the hydraulic pressure in the pressure receiving chamber, an inching region where each clutch is in a non-completely engaged state due to a change in the operation amount, and a brake region where the brake means operates An inching operation means, an inching operation amount detection means for detecting an operation amount of the inching operation means, and a detection of the inching operation amount detection means. When it is determined that the operation position of the inching operation means is in the inching region based on the signal, the control is performed so that the clutch on the connection side among the clutches is set to the clutch engagement pressure corresponding to the operation amount of the inching operation means. And a control means for controlling the brake control valve so as to set the brake means to a clutch engagement pressure corresponding to the operation amount of the inching operation means when it is determined that the valve is in the brake region. The forward clutch and the reverse clutch also serve as the brake means, and the control valve also serves as the brake control valve. When the control means determines that the operation position is in the brake region, the forward clutch The control valve is controlled so that the clutch and the reverse clutch are simultaneously engaged and the clutch engagement pressures have the same pressure value. .
[0007]
In the invention according to claim 2, in the invention according to claim 1, The control means simultaneously engages the forward clutch and the reverse clutch in a state in which the forward clutch remains at a predetermined clutch engagement pressure when shifting from the inching region to the brake region. .
[0008]
According to a third aspect of the present invention, in the first or second aspect of the present invention, a pedaling force detection unit that detects a pedaling force for stepping on the inching operation unit in the brake region is provided, and the control unit detects the pedaling force detection. The brake control valve is controlled so as to obtain a clutch engagement pressure that obtains a braking force corresponding to the pedaling force based on a detection signal from the means.
[0009]
According to a fourth aspect of the present invention, in the first to third aspects of the invention, the industrial vehicle includes a load detection unit that detects a load of a load to be loaded, and the control unit detects the load detection unit. Based on the signal, the control valves are controlled so that the clutch engagement pressure in the inching region becomes a value corresponding to the load.
[0010]
According to a fifth aspect of the present invention, in the first to fourth aspects of the present invention, the industrial vehicle includes a parking brake means and a vehicle speed detecting means, the vehicle is at a stop vehicle speed, and the inching operation means is the brake. A parking brake control means is provided for operating the parking brake means when it is determined that the operation position of the area is held for a predetermined time.
[0011]
According to a sixth aspect of the present invention, in the first to third aspects of the present invention, the control means is configured to detect the clutch of the brake means in the initial operation area of the brake area based on a detection signal from the pedaling force detection means. The engagement pressure is set to a constant initial pressure.
[0012]
(Function)
According to the first aspect of the present invention, when one of the hydraulic clutches provided in the transmission is engaged, the output of the engine is transmitted to the drive wheels, and the vehicle moves forward or backward. When the control means determines that the operation position of the inching operation means is in the inching region based on the detection signal of the inching operation amount detection means, the clutch on the connection side is a half clutch of the clutch engagement pressure corresponding to the operation amount of the inching operation means. The control valve is controlled so that If it is determined that the brake region is reached, the brake control valve is controlled so that the brake means has a clutch engagement pressure corresponding to the operation amount of the inching operation means.
[0013]
Also The simultaneous engagement of the forward clutch and the reverse clutch acts as a brake. Therefore, the braking force loss due to the slip inside the torque converter that occurs when only the clutch pressure opposite to the traveling direction is increased is unlikely to occur, so that a sufficient deceleration effect can be obtained.
[0014]
According to the invention described in claim 3, in addition to the operation of the invention described in claim 1 or 2, when the inching operation means is stepped on the brake region, it is based on the detection signal from the pedaling force detection means. Since the clutch engagement pressure is in accordance with the pedal effort, a braking force in accordance with the pedal effort is obtained.
[0015]
According to the invention described in claim 4, in addition to the operation of the invention described in claims 1-3, the clutch engagement pressure when the inching operation is performed based on the detection signal from the load detection means is applied to the load. Therefore, the inching feeling when operating the inching operation means is almost constant regardless of the presence or absence of the load and its weight.
[0016]
According to the fifth aspect of the present invention, in addition to the action of the first to fourth aspects of the invention, when the inching operation means is held at the operation position in the brake region for a predetermined time in the state of the stopped vehicle speed. The parking brake means is activated. Therefore, for example, it is not necessary to operate a brake lever or the like when parking, and it is not necessary to continue to step on the inching operation means when stopping on a slope.
[0017]
According to the invention described in claim 6, in addition to the operation of the invention described in claims 3 to 5, even if the detection value of the pedal force detection means includes a variation error while the pedal force is small, Regardless of the detected value, the brake means is engaged at a constant initial pressure, so that a predetermined braking force is reliably generated even when the pedaling force is small.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment in which the present invention is embodied in a forklift as an industrial vehicle will be described with reference to FIGS.
[0019]
As shown in FIG. 1, the output shaft 1 a of the engine 1 is connected to a transmission 3 having a torque converter 2, and the transmission 3 is connected to an axle 6 having drive wheels 5 via a differential device 4. . 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 rotational speed of the engine 1, that is, the rotational speed of the output shaft 1 a of the engine 1 is adjusted. Adjusted.
[0020]
The transmission 3 includes an input shaft (main shaft) 3a and an output shaft (counter shaft) 3b. The input shaft 3a is provided with a forward clutch 8 and a reverse clutch 9 as brake means. Gear trains (not shown) are respectively 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 each gear train. Communicated. Both clutches 8 and 9 are hydraulic clutches. In this embodiment, a wet multi-plate clutch is used, 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. When the pressure is increased, the connection force is increased. In the forward clutch 8 and the reverse clutch 9, the oil pressure in the pressure receiving chambers 8a and 9a is controlled by the hydraulic pressure supplied through the forward clutch valve 10 and the reverse clutch valve 11 as control valves. The forward clutch valve 10 and the reverse clutch valve 11 are constituted by proportional solenoid valves having an opening degree proportional to the energization amount to the solenoid. The drive transmission shaft is composed of an input shaft 3a and an output shaft 3b.
[0021]
The output shaft 3b of the transmission 3 is provided with a parking brake 12 as parking brake means, and the parking brake 12 includes a disk 12a and a brake pad 12b. The brake pad 12b is urged in the direction in which it is 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 the applied hydraulic pressure. An electromagnetic valve is used as the brake valve 13.
[0022]
In FIG. 1, the torque converter 2, the transmission 3, and the valves 10, 11, and 13 are illustrated independently, but these devices are incorporated in a single housing to constitute an automatic transmission. A hydraulic pump (not shown) is incorporated in the transmission 3 so that oil discharged from the hydraulic pump can be supplied to the pressure receiving chambers 8a, 9a, and 12c via a flow path (not shown) and the valves 10, 11, and 13. Has been. The hydraulic pump is driven by the rotational force transmitted to the transmission 3 when the engine 1 rotates.
[0023]
A gear 14 is provided on the input shaft 3a of the transmission 3 so as to be integrally rotatable, and the rotational speed of the input shaft 3a is detected by a turbine rotational speed sensor 15 comprising a magnetic pickup. The turbine rotation speed sensor 15 outputs a pulse signal proportional to the rotation speed of the input shaft 3a. A gear 16 is provided on the output shaft 3b of the transmission 3 so as to be able to rotate integrally, and the rotational speed of the output shaft 3b is detected by a vehicle speed sensor 17 as a vehicle speed detection means including a magnetic pickup. The vehicle speed sensor 17 outputs a pulse signal proportional to the rotation speed of the output shaft 3b.
[0024]
A lift cylinder 20 for raising and lowering a fork 19 as a cargo handling device and a tilt cylinder (not shown) for tilting a mast 21 are connected to a discharge side of a hydraulic pump 18 driven by the engine 1 through a pipe line (not shown). ing. The lift cylinder 20 is provided with a pressure sensor 22 as load detecting means for detecting the load of the fork 19. The pressure sensor 22 detects the hydraulic pressure inside the lift cylinder 20 and outputs a detection signal corresponding to the load of the fork 19.
[0025]
An accelerator pedal 23, an inching pedal 24 as an 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-connected state (half-clutch state) when the forklift travels at a low speed while performing a cargo handling operation.
[0026]
The inching pedal 24 is provided with an inching sensor 26 as an inching operation amount detection means, and the depression amount (pedal stroke) of the inching pedal 24 is detected by the inching sensor 26. The inching sensor 26 is composed of a potentiometer and outputs a current value corresponding to the pedal stroke of the inching pedal 24.
[0027]
As shown in FIG. 2, the inching pedal 24 and the brake pedal 25 are configured to be mechanically interlocked, and a pedaling force detecting means 27 is provided on both the pedals 24 and 25. The pedaling force detection means 27 includes a hydraulic cylinder 29 having a piston 28 that moves when the pedals 24 and 25 are depressed, and a pedaling force detection sensor 30 including a pressure sensor capable of detecting the hydraulic pressure. A restriction member 32 that is movable in the axial direction by a spring 31 is provided in the cylinder 29 at a position opposite to the piston 28, and hydraulic oil is contained in a region defined by the piston 28, the restriction member 32, and the inner surface of the cylinder 29. Yes. The hydraulic pressure in the cylinder 29 is changed by the force (depressing force) to step on the pedals 24 and 25, and the pedaling force detection sensor 30 outputs a detection signal corresponding to the hydraulic pressure.
[0028]
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 25 are moved from the middle. It is configured to be interlocked. The brake pedal 25 is provided with a brake switch 33. When the pedals 24 and 25 are depressed, the brake switch 33 is turned on and a detection signal is output.
[0029]
As shown in FIG. 1, a shift lever (forward / reverse lever) 34 and a cargo handling lever 35 are provided at the front of the cab. The shift switch 36 that detects the position of the shift lever 34 detects whether the shift lever 34 is in the forward position F, the reverse position R, or the neutral position (neutral position) N, and outputs a signal corresponding to each position. To do. The cargo handling lever 35 is provided with a cargo handling lever sensor 37, and the cargo handling lever sensor 37 outputs a detection signal corresponding to the operation amount of the cargo handling lever 35.
[0030]
Next, an electrical configuration for controlling the actuator and each clutch will be described.
The control device 38 as a control means includes a central processing unit (hereinafter referred to as CPU) 39, a read only memory (ROM) 40 as a storage means, a readable / rewritable memory (RAM) 41, an input interface 42 and an output interface 43. It has. The ROM 40 stores a predetermined control program and various data necessary for executing the control program. The RAM 41 temporarily stores the calculation result of the CPU 39. The CPU 39 operates based on a control program stored in the ROM 40. The parking brake control means corresponds to the control device 38.
[0031]
The turbine speed sensor 15, the vehicle speed sensor 17, and the brake switch 33 are connected to the CPU 39 via the input interface 42. The inching sensor 26, the cargo handling lever sensor 37, the pressure sensor 22 and the pedaling force detection sensor 30 are connected to the CPU 39 via an A / D converter and an input interface 42 (not shown).
[0032]
The CPU 39 is connected to the throttle actuator 7, the forward clutch valve 10, the reverse clutch valve 11, and the brake valve 13 through an output interface 43 and a drive circuit (not shown). The CPU 39 inputs the output signals of the sensors 15, 17, 22, 26, 30, 37 and the switch 33 and operates in accordance with various control programs stored in the ROM 40, to the throttle actuator 7 and the valves 10, 11, 13. The control command signal is output.
[0033]
The ROM 40 stores a map M1 in FIG. 3 showing the relationship of the clutch engagement pressure (hereinafter referred to as clutch pressure) with respect to the pedal stroke of the inching pedal 24, and a map M2 in FIG. 4 showing the relationship of the clutch pressure with respect to the brake depression force. Yes. FIG. 3 is a map M <b> 1 when the shift lever 34 is in the forward movement position. The F line represents the clutch pressure of the forward clutch 8, and the R line represents the clutch pressure of the reverse clutch 9. The inching pedal stroke is an inching region from zero to a predetermined stroke, and the braking region is a stroke beyond that. As shown in the maps M1 and M2 in FIGS. 3 and 4, in the brake region, the braking force is obtained by simultaneously engaging the forward clutch 8 and the reverse clutch 9. The clutch pressure (hereinafter referred to as FR simultaneous engagement clutch pressure) for simultaneously engaging the forward clutch 8 and the reverse clutch 9 is set so as to increase as the brake depression force (force to depress the brake pedal) increases. The inching sensor 26 detects the depression amount after the play of the inching pedal 24 is eliminated, and the forward clutch 8 is fully engaged with the clutch pressure Pc when the depression amount of the inching pedal 24 is not detected (see FIG. 3). It becomes.
[0034]
A plurality of map lines Fo, Fk, Fn and the like are stored in the map M1 in the inching region according to the load, and map lines corresponding to detection signals from the pressure sensor 22 are used as appropriate. In FIG. 3, a plurality of map lines for each load are drawn on the same map graph for convenience. In the case of an empty load (no load) in which no load is placed on the fork 19, the clutch pressure in the inching region is determined based on a map line Fo indicated by a broken line, and a map indicated by a solid line in the case of the maximum load (full load). Determined based on line Fn. Between the no-load map line Fo and the full-load map line Fn, a plurality of map lines Fk (k = 1) are set such that the larger the load applied to the fork 19, the greater the clutch pressure setting with respect to the depression amount of the inching pedal 24. , 2... N-1) (only one line indicated by a one-dot chain line is drawn in the figure). The ROM 40 also stores a map M1 when the shift lever 34 is in the reverse position, but only the reverse clutch 9 is engaged in the inching region, so that Fo ... Fn is Ro ... Rn in FIG. The R line is replaced with the F line so that it becomes a line. Instead of the map M1, a relational expression between the pedal stroke of the inching pedal 24 and the clutch pressure may be stored.
[0035]
The ROM 40 stores an FR initial simultaneous engagement clutch pressure Pbini as shown in FIG. In addition, the ROM 40 stores a correction coefficient α (W) for correcting the clutch pressure in the brake region 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.
[0036]
Next, the inching control executed by the CPU 39 will be described using the flowchart shown in FIG. During the operation of the forklift, various detection signals necessary for inching control are input to the CPU 39 from the sensors 22, 26, 30, the switch 33, and the like.
[0037]
First, in step 100 (hereinafter, step is simply referred to as S), a pedal stroke value (depression amount) of the inching pedal 24 is acquired. Next, in S110, it is determined whether the depression stroke of the inching pedal 24 is in the inching region or the braking region based on the pedal stroke value. If it is the inching area, the process proceeds to S120, and if it is not the inching area but the brake area, the process proceeds to S140.
[0038]
If it is the inching region, the forward clutch pressure for the inching pedal stroke is obtained from the map M1 stored in the ROM 40 in S120. At this time, a map line corresponding to the load W obtained based on the detection signal from the pressure sensor 22 is selected, and the clutch pressure for the pedal stroke is obtained with reference to the map line. In the next S130, a command current value Iist corresponding to the clutch pressure is commanded to the forward clutch valve 10. The forward clutch valve 10 is controlled based on the command current value Iist, and the forward clutch 8 has a clutch pressure corresponding to the pedal stroke. As a result, the inching feeling is almost constant regardless of the presence or absence of the load on the fork 19 and the load.
[0039]
On the other hand, if it is the brake region, the FR initial simultaneous engagement pressure Pbini (see FIG. 5) is set from the data stored in the ROM 40 in S140. Next, in S150, the FR simultaneous engagement pressure Pbst corresponding to the depression force of the inching pedal 24 is obtained from the map line. Next, in S160, it is determined whether Pbini is larger than Pbst. If it is determined that Pbini is large, the process proceeds to S170, and if it is determined that Pbst is large, the process proceeds to S190.
[0040]
If Pbini is larger, correction is performed by multiplying the value of Pbini by a correction coefficient α (W) corresponding to the load W determined from the detection value of the pressure sensor 22 in S170. In step S180, the forward clutch valve 10 and the reverse clutch valve 11 are commanded with a command current value IPbini corresponding to the corrected Pbini. When the brake pedal force is weak, the detection value of the pedal force detection sensor 30 may vary, but in a region where the brake pedal force is weak, a predetermined FR initial simultaneous engagement pressure Pbini is established. A constant initial brake pressure (braking force) can be obtained with certainty.
[0041]
If Pbst is larger, correction is performed by multiplying the value of Pbst by a correction coefficient α (W) corresponding to the load W in S190. In step S200, a command current value IPbst corresponding to the corrected Pbst is commanded to the forward clutch valve 10 and the reverse clutch valve 11. Accordingly, a braking force corresponding to the brake depression force can be obtained. Further, by correcting the value of the FR simultaneous engagement pressure, the FR simultaneous engagement pressure increases as the load increases, and as a result, the brake feeling is substantially constant without being affected by the presence or absence of the load or the difference in load. .
[0042]
At the switching point where the inching region is switched to the brake region, as shown in FIG. 3, the clutch pressure of the forward clutch 8 is simultaneously engaged with the reverse clutch 9 while leaving a predetermined clutch pressure. For this reason, it is difficult for a deceleration shock to occur when the FR simultaneous engagement pressure is raised at this switching point. Further, since the FR simultaneous engagement is performed, unlike the case where the clutch pressure only on the reverse side is increased, a loss of braking force due to slip inside the torque converter 2 is less likely to occur, and a sufficient braking force can be obtained. The operation of the brake device described above is performed when the inching pedal 24 is depressed. However, since the inching pedal 24 and the brake pedal 25 are interlocked, the operation is similarly performed when the brake pedal 25 is depressed. To do.
[0043]
Further, when the vehicle speed becomes equal to or lower than the stop vehicle speed and the inching pedal 24 is depressed in the brake pedal 25 or in the brake region for a predetermined time (for example, about 0.5 seconds), the CPU 39 sets the brake valve 13 to the pressure receiving chamber of the parking brake 12. It controls so that the pressure of 12c may become high. And when the pressure receiving chamber 12c becomes a high pressure, the brake pad 12b and the disk 12a are engaged, and the parking brake 12 is operated. Further, when the accelerator pedal 23 is depressed, the operation of the parking brake 12 is released. The above-described operation is performed when the forklift is moving forward, but in the case of reverse traveling, the same operation is performed simply by reversing the forward / reverse travel.
[0044]
Therefore, in this embodiment, the following effects can be obtained.
(1) Since the forward clutch 8 and the reverse clutch 9 are used as a brake device, there is no need for a service brake such as a drum brake, so no maintenance is required when the drum brake is used, and the structure of the forklift can be simplified. . In particular, since the clutches 8 and 9 built in the transmission 3 are wet clutches, even when used as a brake, the clutches 8 and 9 are hardly worn as compared with the dry type and can be a substantially maintenance-free brake device.
[0045]
(2) Since the forward clutch 8 and the reverse clutch 9 are simultaneously engaged, a sufficient braking force can be obtained. In particular, since the engagement pressure is the same value, the vehicle can be stopped.
[0046]
(3) At the switching point of switching from the inching region to the brake region, the forward clutch 8 and the reverse clutch 9 are simultaneously engaged with the clutch pressure of the forward clutch 8 (9) remaining a little. As a result, a deceleration shock can be prevented when shifting from the inching region to the brake region.
[0047]
(4) Since the pedal effort detection sensor 30 is provided, the brake depression force when the inching pedal 24 or the brake pedal 25 is depressed is detected, and the FR simultaneous engagement pressure corresponding to the brake depression force is obtained. Brake force can be obtained.
[0048]
(5) In the inching region where the inching pedal 24 is depressed, the clutch pressure is obtained in consideration of the load applied to the fork 19 when obtaining the clutch pressure corresponding to the pedal stroke. As a result, the inching feeling can be made constant regardless of the presence / absence of a load and the difference in load. Further, since the FR simultaneous engagement pressure is corrected to be high when a load is applied, a substantially constant brake feeling can always be obtained regardless of the presence or absence of the load and the difference in load.
[0049]
(6) Since the parking brake 12 is operated when the vehicle is in a stopped vehicle speed state and the brake pedal 25 is operated within a predetermined time, the brake lever can be eliminated and the brake pedal 25 needs to be kept depressed. It can be lost. For example, when the forklift is stopped on a slope, the vehicle can be stopped even if the brake pedal 25 is released, and the rollback does not occur at the subsequent start.
[0050]
(7) In the region where the brake pedal force is weak, an error is likely to occur in the detection value of the pedal force detection sensor 30, but since the FR initial simultaneous engagement pressure Pbini has a constant value regardless of the detected value of the brake pedal force, the brake pedal force is weak. Even within the range, the necessary braking force can be reliably obtained.
[0051]
In addition, embodiment is not limited to the above, For example, you may change as follows.
The value of the FR simultaneous engagement pressure is not limited to the same value in the forward clutch 8 and the reverse clutch 9. For example, the forward clutch 8 and the reverse clutch 9 are simultaneously engaged, but the clutch pressures may be different. In this case, it is possible to shift to FR simultaneous engagement when the vehicle speed is reduced and the vehicle speed becomes the stop vehicle speed, or to the parking brake 12 when the vehicle speed becomes the stop vehicle speed.
[0052]
The FR simultaneous engagement pressure that operates as a brake is not limited to being obtained by the depression force of the brake pedal 25 or the inching pedal 24. For example, the FR simultaneous engagement pressure may be obtained according to the depression amount of each pedal 24, 25.
[0053]
The brake means is not limited to the forward clutch 8 and the reverse clutch 9. For example, the parking brake 12 may be operated as a brake means when the inching pedal 24 moves to the brake region or when the brake pedal 25 is operated. At this time, the brake valve 13 is composed of a proportional solenoid valve. In this case, the brake control valve corresponds to the brake valve 13, and the pressure receiving chamber of the brake means corresponds to the pressure receiving chamber 12c.
[0054]
○ When the forward clutch 8 and the reverse clutch 9 are simultaneously engaged, it is not limited to leaving a little clutch pressure on the advancing side, and both the clutches 8 and 9 are simultaneously engaged when the both clutches 8 and 9 are completely disconnected. May be.
[0055]
○ It is not limited to setting the FR initial simultaneous engagement pressure in a region where the brake pedal force is weak, and if the detection accuracy of the pedal force detection sensor 30 is high, the FR simultaneous engagement pressure is based on the detection signal even when the pedal force is small. You may ask for.
[0056]
○ In the inching area and the brake area, the clutch pressure is determined in consideration of the load. However, the present invention is not limited to this. The load may be considered in either the inching area or the brake area, or the load may not be considered. Good.
[0057]
The clutch brake means may be disposed anywhere on the drive transmission shaft between the torque converter 2 and the drive wheel 5. For example, the parking brake 12 may be provided on a propeller shaft provided between the transmission 3 and the differential device 4.
[0058]
The brake pedal 25 and the inching pedal 24 are not limited to being linked to each other, and may function separately.
In the map M1 showing the relationship between the inching pedal stroke and the clutch pressure, the clutch pressure may be set to be higher at no load and the clutch pressure may be set to be lower at full load.
[0059]
The industrial vehicle is not limited to a forklift, and may be an industrial vehicle such as an excavator loader.
Can be grasped from the embodiment and other examples Technique The technical idea is described below along with its effects.
[0060]
(1 )in front When the control means shifts from the inching region to the brake region, the forward clutch and the reverse clutch are simultaneously engaged with a little clutch engagement pressure on the advancing side remaining. In this case, the occurrence of deceleration shock can be prevented by leaving a little clutch on the traveling side.
[0061]
(2 )in front The clutch engagement pressure when the forward clutch and the reverse clutch are simultaneously engaged is the same pressure value. In this case, a sufficient braking force can be obtained and the stopped state can be maintained.
[0062]
(3) In the inventions according to claims 1 to 6, the inching pedal and the brake pedal are configured to be interlocked. In this case, since the brake operated by depressing the inching pedal and the brake operated by depressing the brake pedal are common brake means, the number of parts can be reduced.
[0063]
(4) In the invention of claim 4, the control means controls the control valves based on the detection signal of the load detection means so that the clutch engagement pressure in the brake region becomes a value corresponding to the load. In this case, a substantially constant brake feeling can be obtained without being affected by the presence or absence of a load.
[0064]
(5) In Claim 1, the brake means is a wet clutch. In this case, since it is a wet clutch, even if it is used as a brake, it is difficult to deteriorate and can be a highly durable brake.
[0065]
(6 )in front The forward clutch and the reverse clutch are wet clutches. In this case, since it is a wet clutch, even if it is used as a brake, it is difficult to deteriorate and can be a highly durable brake.
[0066]
【The invention's effect】
As described above in detail, according to the first to sixth aspects of the present invention, since the clutch is used as the brake device, the frequency of maintenance such as replacement of parts of the brake device can be reduced.
[0067]
Also By using the forward / reverse clutch as a brake, there is no need to newly install a brake device, and the structure can be simplified.
[0068]
According to the fourth aspect of the invention, in addition to the effects of the first to third aspects of the invention, the load detecting means detects the load and adjusts the clutch engagement pressure. Regardless of this, an almost constant inching feeling can always be obtained.
[0069]
According to the fifth aspect of the present invention, in addition to the effects of the first to fourth aspects of the invention, when the brake operating means is continuously operated at the stop vehicle speed, the parking brake is actuated to activate the parking brake lever. Thus, it is possible to eliminate the need to continue operating the brake operating means even when the vehicle stops on a slope.
[0070]
According to the invention of claim 6, in addition to the effects of the inventions of claims 3 to 5, a constant clutch engagement pressure is established in a region where the pedal force is weak. Even if the pedaling force is weak, a constant braking force can be reliably obtained.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a forklift according to an embodiment.
FIG. 2 is a schematic diagram showing the structure of a pedaling force detection means.
FIG. 3 is a map showing the relationship between the FR simultaneous engagement pressure and the pedal stroke.
FIG. 4 is a map showing the relationship between brake pedal force and FR simultaneous engagement pressure.
FIG. 5 is a diagram showing the relationship between the pressure of the pedal effort detection sensor and the FR simultaneous engagement pressure.
FIG. 6 is a flowchart of the inching control device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Engine, 2 ... Torque converter, 3 ... Transmission, 3a ... Input shaft as drive transmission shaft, 3b ... Output shaft as drive transmission shaft, 5 ... Drive wheel, 8 ... Forward clutch, 8a ... Pressure receiving chamber, 9 ... reverse clutch, 9a ... pressure receiving chamber, 10 ... forward clutch valve as control valve and brake control valve, 11 ... reverse clutch valve as control valve and brake control valve, 12 ... parking as brake means and parking brake means Brake, 12c ... pressure receiving chamber, 13 ... brake valve as brake control valve, 17 ... vehicle speed sensor as vehicle speed detection means, 22 ... pressure sensor as load detection means, 24 ... inching pedal as inching operation means, 26 ... Inching sensor as inching operation amount detection means, 27 ... Treading force detection means, 30 ... Treading force constituting the treading force detection means Detection sensor, 38 ... control unit and the control device as the brake control means.

Claims (6)

In an industrial vehicle equipped with a transmission having a hydraulic forward clutch and a reverse clutch that transmits the output of an engine to drive wheels via a torque converter,
A control valve for adjusting the connection state by increasing or decreasing the hydraulic pressure in the pressure receiving chamber of each clutch;
Clutch-type brake means provided on a drive transmission shaft between the torque converter and the drive wheel;
A brake control valve for adjusting the connection state by increasing or decreasing the hydraulic pressure in the pressure receiving chamber of the brake means;
An inching region where each clutch is in a non-completely engaged state due to a change in an operation amount; an inching operation means serving as a brake region where the brake means operates;
An inching operation amount detection means for detecting an operation amount of the inching operation means;
Based on the detection signal of the inching operation amount detection means, when it is determined that the operation position of the inching operation means is in the inching region, the clutch on the connection side among the clutches is engaged according to the operation amount of the inching operation means. The control valve is controlled so as to have a combined pressure, and when it is determined that the brake valve is in the brake region, the brake control valve is set so that the brake means has a clutch engagement pressure corresponding to the operation amount of the inching operation means. Control means for controlling ,
The forward clutch and the reverse clutch also serve as the brake means, and the control valve also serves as the brake control valve. When the control means determines that the operation position is in the brake region, the forward clutch And an inching control device for an industrial vehicle that simultaneously controls the reverse clutch and controls the control valves so that the clutch engagement pressures have the same pressure value . 2. The control device according to claim 1, wherein the control means simultaneously engages the forward clutch and the reverse clutch in a state in which the clutch on the advancing side remains at a predetermined clutch engagement pressure when shifting from the inching region to the brake region. An inching control device for an industrial vehicle as described. A pedaling force detection unit that detects a pedaling force for stepping on the inching operation unit in the brake region is provided, and the control unit is configured to have a clutch engagement pressure that obtains a braking force according to the pedaling force by a detection signal from the pedaling force detection unit. The inching control device for an industrial vehicle according to claim 1 or 2, wherein the brake control valve is controlled. The industrial vehicle includes load detection means for detecting a load of a load to be loaded, and the control means is configured so that the clutch engagement pressure in the inching region becomes a value corresponding to the load based on a detection signal of the load detection means. The inching control device for an industrial vehicle according to any one of claims 1 to 3, wherein each control valve is controlled. The industrial vehicle includes a parking brake means and a vehicle speed detection means, and activates the parking brake means when it is determined that the vehicle is at a stop vehicle speed and the inching operation means is held at the operation position in the brake region for a predetermined time. The inching control device for an industrial vehicle according to any one of claims 1 to 4, further comprising a parking brake control means. The control means is set so that a clutch engagement pressure of the brake means is a constant initial pressure in an initial operation region of the brake region based on a detection signal from the pedaling force detection means. The inching control device for an industrial vehicle according to any one of 5.

Images