JP4681412B2 - vehicle - Google Patents

Description

  The present invention relates to an actuator for driving a cargo handling member used at the time of cargo handling work, and a vehicle in which drive wheels are operated by power from the same engine.

  2. Description of the Related Art Conventionally, a forklift is configured to operate an actuator for driving a cargo handling member such as a fork or a rotation attachment, and a driving wheel with power from the same engine.

  Of these types of forklifts, forklifts equipped with an automatic transmission equipped with a torque converter are provided between the torque converter and the transmission in order to suppress the power transmitted from the engine to the drive wheels during cargo handling operations. A clutch that engages the output shaft of the torque converter and the input shaft of the transmission in response to the hydraulic pressure generated by the rotation of the engine and the hydraulic path from the hydraulic pump to the clutch. And an inching valve that depressurizes the hydraulic pressure transmitted to. In this forklift, the operator operates the inching pedal provided in the driver's seat (depresses) to operate the inching valve, so that the clutch engagement state is completely changed from the engagement state where the clutch is completely engaged. The power transmitted from the engine to the drive wheels can be suppressed by engaging the clutch in the half-clutch state where the clutch is not engaged with the clutch. The power transmitted from the engine to the drive wheels can be cut off by opening the gears so that they do not match (see, for example, Patent Document 1).

The inching pedal is provided in the driver's seat together with the accelerator pedal and the brake pedal, and is used to apply braking force to the wheels in the interlocking section from the position depressed by a predetermined amount by the operator to the position fully depressed. The brake pedal is linked. The brake pedal operates independently of the inching pedal. However, when the inching pedal is operated, the brake pedal operates in conjunction with the inching pedal in the interlocking section.
Japanese Patent Laid-Open No. 9-25960

  By the way, in order to prevent power from being transmitted to the driving wheels, the cargo handling operation when the conventional forklift is stopped is normally performed in a state where the inching pedal is fully depressed by the operator (that is, the clutch is in the released state). .

  However, if this cargo handling operation continues for a long time, the inching pedal may float due to operator fatigue, for example, and the clutch may be in a half-clutch state.

  When the clutch is in the half-clutch state, the engine power is transmitted to the drive wheels, so the operator notices that the clutch has been in the half-clutch state as the forklift starts running, but the inching pedal is depressed. In this case, since the brake pedal operates in conjunction with the inching pedal, a braking force is applied to the drive wheels, so that the forklift may not start even if power is transmitted to the drive wheels.

  In other words, in a conventional forklift, when the inching pedal is operated, even if power is transmitted to the driving wheel, the braking force applied to the driving wheel by the operation of the brake pedal is greater than the power transmitted to the driving wheel. In this case, the forklift will not run.

If the forklift does not start in this way, even if the clutch is in a half-clutch state, the operator will not be aware of this and will continue the cargo handling operation.
When the half-clutch state continues for a long time in this way, the temperature of the oil transmitted to the automatic transmission rises due to frictional heat generated by friction within the clutch, and the durability of the automatic transmission deteriorates due to the thermal effect. There was a problem of doing.

  The present invention has been made to solve these problems. In a vehicle in which an actuator for driving a cargo handling member and a drive wheel are operated by power from the same engine, the temperature of oil transmitted to an automatic transmission is determined. The purpose is to suppress the rise of.

In order to achieve the above object, an invention according to claim 1 is directed to an engine, driving means for driving a cargo handling member for cargo handling work in accordance with a command from an operator, and a cargo handling system for transmitting engine power to the driving means. Power transmission means, traveling system power transmission means for transmitting engine power to the drive wheels via a torque converter and transmission, and a power transmission path from the torque converter to the drive wheels, and generating hydraulic pressure by engine rotation By receiving the hydraulic pressure from the hydraulic source, the clutch that connects the power transmission path, the inching valve that is provided in the hydraulic path for transmitting the hydraulic pressure from the hydraulic source to the clutch, and that reduces the hydraulic pressure transmitted to the clutch, by the operator according depressing actuates the inching valve, fully depressed the predetermined amount depressed position by the operator The interlocking section up or position, the inching pedal to link the brake pedal for applying a braking force to the wheels, in a vehicle equipped with, when the inching pedal is depressing, via the hydraulic path from the hydraulic source A temperature rise detecting means for detecting a temperature rise of the oil supplied to the clutch, and a prohibiting means for prohibiting transmission of power from the engine to the driving means when the temperature rise detecting means detects the temperature rise of the oil. It is characterized by having prepared.

  In such a vehicle according to the first aspect, when an increase in the temperature of the oil supplied from the hydraulic pressure source to the clutch is detected when the inching pedal is operated (depressed) by the operator, In order to prohibit transmission of power, the cargo handling member stops its operation.

  For this reason, the operator can be made aware that the temperature rise of the oil supplied from the hydraulic pressure source to the clutch has been detected (for example, the inching pedal that should have been fully depressed has floated).

  Therefore, when an operator who has noticed this, for example, fully depresses the inching pedal, the temperature of the oil transmitted from the hydraulic power source to the traveling system power transmission means can be suppressed from rising due to the frictional heat of the clutch. .

  By the way, when the shift position of the transmission is at the neutral position, the temperature of oil transmitted from the hydraulic power source to the traveling system power transmission means does not increase due to friction in the clutch.

For this reason, the vehicle according to claim 1 may be configured as described in claim 2.
That is, the vehicle according to claim 2 is provided with shift position detecting means for detecting a shift position of the transmission in the vehicle according to claim 1, and the prohibiting means has a shift position detected by the shift position detecting means. In the case of the neutral position, the transmission of power to the driving means is not prohibited.

  According to such a vehicle of the second aspect, when the shift position is in the neutral position, the cargo handling operation by the operator can be continued by prohibiting the operation of the prohibiting means.

Therefore, when the shift position is the neutral position, the operator does not have to interrupt the cargo handling operation, and therefore it is possible to prevent the work efficiency from being lowered.
Next, the vehicle according to claim 3 is the vehicle according to claim 1 or 2, further comprising accelerator operation amount detection means for detecting an accelerator operation amount of the engine, and the prohibition means is an accelerator operation amount detection means. When the accelerator operation amount detected by the above is less than a predetermined value, the transmission of power to the drive means is not prohibited.

  According to the vehicle of the third aspect, the predetermined value that is compared with the accelerator operation amount by the prohibiting unit, for example, even if the clutch is in the half-clutch state, the traveling system power transmission unit is affected by the frictional heat. By setting the value to a value that is not, the cargo handling work can be performed while traveling.

  Next, a vehicle according to a fourth aspect is the vehicle according to any one of the first to third aspects, comprising: a cargo handling operation detecting means for detecting that a driving command for a cargo handling member has been input; and a cargo handling operation detecting means. And a first speed limiting means for limiting the maximum engine speed to a first set value less than the upper limit when it is detected that a driving command for the cargo handling member has been input. Yes.

According to the vehicle described in claim 4, since a large force is not suddenly applied to the cargo handling member during the cargo handling operation by the operator, safety can be ensured.
Next, the invention according to claim 5 is an engine, driving means for driving a cargo handling member for cargo handling work in accordance with a command from an operator, cargo handling system power transmission means for transmitting engine power to the driving means, and engine The hydraulic power from a hydraulic power source that is provided in a power transmission path from the torque converter to the drive wheel and that generates hydraulic pressure by the rotation of the engine is transmitted to the drive wheel via the torque converter and the transmission. The inching valve is provided in the clutch for connecting the power transmission path, the hydraulic path for transmitting the hydraulic pressure from the hydraulic power source to the clutch, and the inching valve according to the stepping operation by the operator. actuating the interlocking section to a position fully depressed a predetermined amount by depressed position by the operator Includes inching pedal to link the brake pedal for applying a braking force to the wheels, in a vehicle equipped with, when the inching pedal is depressing, the oil supplied to the clutch through the hydraulic passage from the hydraulic source A temperature rise detecting means for detecting a temperature rise, and a second speed limit for restricting the maximum engine speed to a second set value less than the upper limit value when an oil temperature rise is detected by the temperature rise detecting means. Means.

  In such a vehicle according to claim 5, when an increase in the temperature of oil supplied from the hydraulic pressure source to the clutch is detected while the inching pedal is operated by the operator, the maximum engine speed is set to the second value. Limit to value.

  For this reason, the value of the maximum engine speed limited by the second engine speed limiting means is set so that, for example, even if the clutch is in a half-clutch state, the traveling system power transmission means is not affected by the frictional heat of the clutch. By setting the value, it is possible to suppress the oil temperature of the hydraulic pressure source from rising due to the frictional heat of the clutch.

  Furthermore, according to the vehicle of the fifth aspect, when the temperature rise of the oil supplied from the hydraulic pressure source to the clutch is detected, the maximum engine speed is only limited. Can also be done.

  Next, the vehicle according to claim 6 is the vehicle according to claim 5, further comprising shift position detecting means for detecting a shift position of the transmission, and the limiting means is a shift position detected by the shift position detecting means. Is the neutral position, the maximum engine speed is not limited to a predetermined value less than the upper limit value.

  According to such a vehicle of the sixth aspect, when the shift position is in the neutral position, the operation of the limiting means is prohibited, so that it is possible to prevent the work efficiency from being lowered. .

  Next, the vehicle according to claim 7 is provided with cargo handling operation detecting means for detecting that a driving command for the cargo handling member is input in the vehicle according to claim 5 or 6, and the second rotational speed. The limiting means limits the maximum number of revolutions of the engine even when it is detected by the cargo handling operation detection means that a cargo handling member drive command has been input.

According to the vehicle according to the seventh aspect, it is possible to obtain the same effect as that of the fourth aspect.
By the way, the temperature increase detection means may be configured in any way as long as it is configured to detect the temperature increase of the oil supplied from the hydraulic pressure source to the clutch.

  For example, as described in claim 8, it may be configured to detect an increase in the temperature of the oil based on the operation amount of the inching pedal, or as described in claim 9, from the hydraulic pressure source to the clutch. The oil temperature increase may be detected based on the transmitted oil pressure, or the oil temperature increase may be detected based on the oil temperature of the hydraulic power source. May be.

  In this way, it is possible to reliably detect an increase in the temperature of the oil supplied from the hydraulic pressure source to the clutch.

Hereinafter, a forklift according to a first embodiment to which the present invention is applied will be described with reference to the drawings.
The forklift of this embodiment is an automatic transmission vehicle equipped with a torque converter, and is configured to operate actuators and driving wheels for raising and lowering and rotating the fork with power from the same engine. It is a thing. 1 is an overall view of the forklift 1, FIG. 1A is a side view showing the forklift 1 in a state in which the lifting body 3 provided with the forks 11 is lowered, and FIG. FIG. 1A is a front view of FIG. 1A, and FIG. 1C is a front view of the forklift 1 in a state where the fork 11 is rotated. FIG. 2 is an explanatory diagram for explaining the internal configuration of the forklift 1.

  As shown in FIGS. 1A to 1C, the forklift 1 according to the present embodiment includes a main body 2 having a driver's seat 15 for an operator to get on and sit on, and a mast disposed in front of the main body 2. And a lifting / lowering body 3 arranged so as to be able to be lifted / lowered.

  A fork 11 for inserting the load 3 on the lower side of the load and placing the load, and a rotating attachment 12 for rotating the fork 11 with respect to the lift 3 as shown in FIG. Is provided.

  One front wheel 13 is provided on the left and right in front of the main body 2, and one rear wheel 14 is provided on the left and right behind the main body 2. The front wheel 13 is a driving wheel, and the rear wheel 14 is an idle wheel.

  Further, in front of the driver's seat 15, a steering 16 for steering while the forklift 1 is traveling and a shift lever 20 for an operator to perform a shift change are provided.

  Further, in front of the driver's seat 15, as shown in FIG. 2, a lift lever 17 for the operator to raise and lower the fork 11 (elevating body 3), and the operator tilts the fork 11. A tilt lever 18 for performing an adjustment operation and a rotation lever 19 for an operator to rotate the fork 11 (rotation attachment 12) are provided.

  Further, below the driver's seat 15, as shown in FIG. 2, an accelerator pedal 21, a brake pedal (not shown), and an operator depressing operation from the engine 30 to the drive wheel 13 via the automatic transmission 32. An inching pedal 22 for suppressing the transmitted power is provided.

  Note that the inching pedal 22 is configured to interlock the brake pedal in an interlocking section from a position where the operator is depressed by a predetermined amount to a position where the inching pedal 22 is completely depressed. The brake pedal operates independently of the inching pedal 22, but when the inching pedal 22 is operated, it operates in conjunction with the inching pedal 22 in the interlocking section.

Next, the internal configuration of the forklift 1 according to this embodiment will be described.
As shown in FIG. 2, the forklift 1 includes an engine 30, an automatic transmission 32 that transmits power of the engine 30 to the drive wheels 13, hydraulic pumps 40 and 42, a lift cylinder 44 for raising and lowering the fork 11, 11 is connected to a tilt cylinder 46 for adjusting the tilt of the motor 11, a hydraulic motor 48 for rotating the fork 11, and a discharge port of the hydraulic pump 40, and supplies / discharges oil from the hydraulic pump 40 to the automatic transmission 32. A hydraulic circuit for traveling 50, a hydraulic circuit for cargo handling 70 for driving the lift cylinder 44, the tilt cylinder 46, and the hydraulic motor 48 connected to the discharge port of the hydraulic pump 42, and the hydraulic circuits 50, 70. A solenoid valve driving circuit 9 for driving provided solenoid valves 56 and 74 described later. It is equipped with a door.

In the following description, when the hydraulic pumps 40 and 42 are distinguished, the hydraulic pump 40 is referred to as a traveling pump 40 and the hydraulic pump 42 is referred to as a cargo handling pump 42.
The drive shafts of the hydraulic pumps 40 and 42 are connected to the rotation shaft of the engine 30 and are operated by the rotation of the engine 30 to generate hydraulic pressure.

  The automatic transmission 32 includes a torque converter 34, a transmission (not shown) disposed between the torque converter 34 and the drive wheel 13, and a clutch 36 disposed between the torque converter 34 and the transmission.

The clutch 36 receives the hydraulic pressure from the traveling pump 40 to engage the output shaft of the torque converter 34 and the input shaft of the transmission.
The traveling hydraulic circuit 50 is disposed in a clutch hydraulic line 52 extending from the discharge port of the traveling pump 40 to the clutch 36, and an inching valve 54 for reducing the hydraulic pressure transmitted to the clutch 36, and in the clutch hydraulic line 52, the clutch 36 Between the traveling pump 40 and the inching valve 54 for switching the flow direction of the oil supplied from the traveling pump 40 to the clutch 36, and the discharge port of the traveling pump 40 to the torque converter 34. A regulator valve 60 disposed in the torque converter hydraulic line 58, and an oil cooler 64 and return filter 66 disposed in the cooling hydraulic line 62 extending from the torque converter 34 to the clutch 36.

The inching valve 54 is a three-position three-port direction switching valve and is operated according to the operation of the inching pedal 22 by the operator.
Further, the inching valve 54 communicates the clutch hydraulic line 52 at a normal position where the inching pedal 22 is not operated by the operator (a position shown in FIG. 2), and the flow rate of oil to the clutch 36 causes the clutch 36 to be completely closed. The amount can be held in a connected state.

  In addition, the inching valve 54 allows the clutch hydraulic line 52 to communicate with the clutch hydraulic line 52 through the throttle when the inching pedal 22 is switched to the position b shown in FIG. In communication with the tank, the flow rate of oil to the clutch 36 is set to an amount capable of holding the clutch 36 in a half-clutch state.

  In addition, the inching valve 54 supplies oil to the clutch 36 in a state where the inching pedal 22 is switched to the position c shown in FIG. 2 (that is, the inching pedal 22 is fully depressed) by operating the inching pedal 22. The oil supplied to the clutch 36 is guided to the oil tank.

  The forward / backward electromagnetic valve 56 is a three-position / four-way switching electromagnetic valve. The electromagnetic valve drive circuit 90 changes the forward coil 56a or the reverse coil 56b of the electromagnetic valve 56 according to switching of the shift position of the shift lever 20. Operates when energized.

  The forward / reverse solenoid valve 56 is in the N position shown in FIG. 2 when the energization is not performed (that is, when the shift position of the shift lever 20 is in the neutral position). By switching to the F position shown in FIG. 2, the forklift 1 can be moved forward. Further, when the reverse coil 56b is energized, the forward / reverse solenoid valve 56 is switched to the R position shown in FIG. 2 so that the forklift 1 can be moved backward.

  The regulator valve 60 is for adjusting the hydraulic pressure from the traveling pump 40 to a set pressure value, and prevents the torque converter 34 and the pressure at the inlet of the torque converter 34 from becoming excessive on the outlet side thereof. A relief valve 68 is connected for this purpose.

The oil cooler 64 is for cooling the oil discharged from the torque converter 34, and the return filter 66 is for removing contaminants mixed in the oil.
The oil supplied from the traveling pump 40 to the torque converter 34 is cooled by the oil cooler 64, circulates through the clutch 36 via the return filter 66, and returns to the oil tank.

  The cargo handling hydraulic circuit 70 is provided in a direction control unit 72 for controlling the direction of the flow of oil discharged from the cargo handling pump 42, and a rotation pipeline 84 from the cargo handling pump 42 to the hydraulic motor 48. And an electromagnetic valve 74 for supplying / blocking oil from the cargo handling pump 42 to / from the hydraulic motor 48.

  The direction control unit 72 is provided in a lift hydraulic line 76 from the cargo handling pump 42 to the lift cylinder 44, and a lift direction switching valve 78 that switches the direction of oil supplied from the cargo handling pump 42 to the lift cylinder 44. A tilt direction switching valve 82 for switching the direction of oil supplied from the cargo handling pump 42 to the tilt cylinder 46, and a rotation pipeline provided in the tilt hydraulic pipeline 80 from the cargo handling pump 42 to the tilt cylinder 46. And a rotation direction switching valve 86 that switches the direction of oil supplied from the cargo handling pump 42 to the hydraulic motor 48.

  The lift direction switching valve 78 is a three-position 6-port direction switching valve, and is operated according to the operation of the lift lever 17 by the operator. For this reason, the operator can operate the lift lever 17 to supply / discharge oil from the cargo handling pump 42 to the lift cylinder 44 and to lift and lower the fork 11.

  Further, the tilt direction switching valve 82 is also a three-position six-port direction switching valve and is operated according to the operation of the tilt lever 18 by the operator. Therefore, the operator can tilt the fork 11 by operating the tilt lever 18 to supply / discharge oil from the cargo handling pump 42 to the tilt cylinder 46.

  Further, the rotation direction switching valve 86 is also a 3-position 6-port direction switching valve, and is operated in accordance with the operation of the rotation lever 19 by the operator. Therefore, the operator can rotate the fork 11 by operating the rotation lever 19 so that the oil from the cargo handling pump 42 is supplied to the hydraulic motor 48.

The electromagnetic valve 74 is disposed between the hydraulic motor 48 and the rotation direction switching valve 86 in the rotation pipeline 84.
The solenoid valve drive circuit 90 includes a shift switch 92 having a forward switch 92a that is turned on when the shift position of the shift lever 20 is in the forward position and a reverse switch 92b that is turned on when the shift position of the shift lever 20 is in the reverse position. The forward relay RY1 that switches the energization path in accordance with the on / off switching of the forward switch 92a, the reverse relay RY2 that switches the energization path in accordance with the on / off switching of the reverse switch 92b, and the inching pedal 22 is a predetermined amount or more. An inching switch 94 that is turned on when it is depressed, a throttle switch 96 that is turned on when the rotational speed of the engine 30 exceeds a predetermined rotational speed (for example, 1400 rpm), and a throttle switch 96 that is turned on when the inching switch 94 is turned on. Operational power supply from in-vehicle battery 100 And inching relay RY3 to block the throttle switch 96 is turned on, and an electromagnetic valve relay RY4 connecting the current path from the vehicle battery 100 to the coil 74a.

  In the present embodiment, the inching switch 94 is turned on when the inching pedal 22 is fully depressed. Further, in the present embodiment, the value of the engine speed when the throttle switch 96 is turned on is such a value that the frictional heat is not affected by the automatic transmission 32 even if the clutch 36 is in the half-clutch state.

  The forward switch 92a has one end connected to the positive electrode side of the in-vehicle battery 100 and the other end connected to a ground line connected to the negative electrode side of the in-vehicle battery 100 via the coil L1 of the relay RY1.

  The reverse switch 92b has one end connected to the positive electrode side of the in-vehicle battery 100 and the other end connected to a ground line connected to the negative electrode side of the in-vehicle battery 100 via the coil L2 of the relay RY2.

The forward relay RY1 includes a coil L1, three contact points p1, p2, and p3, and a segment s1 having one end connected to the contact point p3.
The other end of the segment s1 is connected to the contact p1 when the coil L1 is not energized, and is connected to the contact p2 when the coil L1 is energized. That is, the segment s1 is connected to the contact p1 and the contact p3 when the coil L1 is not energized, and is connected to the contact p2 and the contact p3 when the coil L1 is energized.

  Further, the contact point p1 is connected to the ground line via a reverse coil 56b for the forward / backward electromagnetic valve 56. Further, the contact p2 is connected to the positive side of the in-vehicle battery 100, and the contact p3 is connected to a contact p6 of the reverse relay RY2 described later.

The reverse coil 56b is provided with a diode D1 having an anode connected to the end on the ground line side and a cathode connected to the end on the contact p1 side.
The reverse relay RY2 includes a coil L2, three contact points p4, p5, and p6, and a segment s2 having one end connected to the contact point p6.

  The other end of the segment s2 is connected to the contact p4 when the coil L2 is not energized, and is connected to the contact p5 when the coil L2 is energized. That is, the segment s2 is connected to the contact p4 and the contact p6 when the coil L2 is not energized, and is connected to the contact p5 and the contact p6 when the coil L2 is energized.

  Further, the contact p4 is connected to the ground line via the forward coil 56a of the forward / backward electromagnetic valve 56. Further, the contact p5 is connected to the positive electrode side of the in-vehicle battery 100, and the contact p6 is connected to the contact p3 of the forward relay RY1.

The forward coil 56a is provided with a diode D2 having an anode connected to the end on the ground line side and a cathode connected to the end on the contact p4 side.
The inching relay RY3 includes a coil L3, three contacts p7, p8, and p9, and a segment s3 having one end connected to the contact p9.

  The other end of the segment s3 is connected to the contact p7 when the coil L3 is not energized, and is connected to the contact p8 when the coil L3 is energized. That is, the segment s3 is connected to the contact p7 and the contact p9 when the coil L3 is not energized, and is connected to the contact p8 and the contact p9 when the coil L3 is energized.

Further, the contact point p7 is connected to the power supply terminal of the throttle switch 96. The contact p9 is connected to a connection point between the contact p3 and the contact p6.
The coil L3 has one end connected to the inching switch 94 and the other end connected to the ground line.

  The throttle switch 96 has a state in which the inching relay RY3 is turned off (that is, a state in which the inching switch 94 is turned off) and a state in which the forward relay RY1 or the reverse relay RY2 is turned on (that is, the forward switch 92a or the reverse drive). When the switch 92b is turned on), the operation power from the in-vehicle battery 100 is supplied.

The electromagnetic valve relay RY4 includes a coil L4, three contact points p10, p11, and p12, and a segment s4 having one end connected to the contact point p12.
The other end of the segment s4 is connected to the contact p10 when the coil L4 is not energized, and is connected to the contact p11 when the coil L4 is energized. That is, the segment s4 is connected to the contact p10 and the contact p12 when the coil L4 is not energized, and is connected to the contact p11 and the contact p12 when the coil L4 is energized.

The contact p11 is connected to the ground line via the coil 74a of the electromagnetic valve 74, and the contact p12 is connected to the positive electrode side of the in-vehicle battery 100.
The coil L4 has one end connected to the output terminal of the throttle switch 96 and the other end connected to the ground line.

Further, for example, a lamp 98 disposed in the mast 10 is connected to a connection point between the coil 74a of the electromagnetic valve 74 and the contact point p11.
In the electromagnetic valve drive circuit 90 configured as described above, when the shift position of the shift lever 20 reaches the forward position, the forward switch 92a is turned on and the forward relay RY1 is turned on. Then, a current flows through the forward coil 56a of the forward / reverse solenoid valve 56, and the forward / reverse solenoid valve 56 moves to the F position so that the forklift 1 can move forward.

  On the other hand, when the shift position of the shift lever 20 becomes the reverse position, the reverse switch 92b is turned on and the reverse relay RY2 is turned on. Then, a current flows through the reverse coil 56b of the forward / backward electromagnetic valve 56, and the forward / backward electromagnetic valve 56 moves to the R position, so that the forklift 1 can be moved backward.

  In the state where the shift position of the shift lever 20 is the forward position or the reverse position and the inching pedal 22 is not fully depressed (the inching switch 94 is not turned on), the inching relay RY3 is turned off. Since the forward relay RY1 or the reverse relay RY2 is on, operating power is supplied to the throttle switch 96. When the throttle switch 96 is turned on in this state (that is, when the rotational speed of the engine 30 exceeds a predetermined rotational speed), the solenoid valve drive circuit 90 turns on the throttle relay RY4 to drive the solenoid valve 74. As a result, the supply of oil from the cargo handling pump 42 to the hydraulic motor 48 is prohibited.

  On the other hand, the shift position of the shift lever 20 is in the forward or reverse position and the inching pedal 22 is fully depressed, or the shift position of the shift lever 20 is in the neutral position and the inching pedal 22 is fully depressed. In the absence state, the operating power is not supplied to the throttle switch 96, and therefore the throttle switch 96 is not turned on even if the rotational speed of the engine 30 exceeds the predetermined rotational speed.

  As described above, the forklift 1 of the present embodiment is in a state where the inching pedal 22 is not fully depressed (that is, the clutch 36 is completely connected or a half-clutch state), and the shift lever 20 When the rotational speed of the engine 30 becomes equal to or higher than a predetermined rotational speed when the shift position is at the forward drive position or the reverse drive position, the electromagnetic valve 74 is driven to prohibit the rotation of the fork 11.

  Specifically, for example, when the fork 11 is rotated by the operator in a state where the shift position of the shift lever 20 is in the forward position (the forward relay RY1 is on and the reverse relay RY2 is off) at the time of stopping, for example. In addition, when the inching switch 94 is turned off, the inching relay RY3 is turned off, so that the operating power is supplied from the in-vehicle battery 100 to the throttle switch 96. At this time, when the rotational speed of the engine 30 is equal to or higher than the predetermined rotational speed, the electromagnetic valve relay RY4 is turned on and the electromagnetic valve 74 is operated, so that oil from the cargo handling pump 42 is supplied to the hydraulic motor 48. The hydraulic motor 48 is stopped.

  For this reason, according to the forklift 1 of the present embodiment, the operator can notice that the inching pedal 22 that should have been fully depressed has floated while the fork 11 is rotating at the time of stopping. it can.

  Therefore, the operator who has noticed that, for example, by fully depressing the inching pedal 22, suppresses the temperature of the oil transmitted from the traveling pump 40 to the automatic transmission 32 from rising due to the frictional heat of the clutch 36. Thus, the life of the clutch 36 (and hence the automatic transmission 32) can be extended.

  Further, according to the forklift 1 of the present embodiment, since the lamp 98 is turned on when the rotation of the fork 11 by the operator is prohibited, it is ensured that the inching pedal 22 that should have been fully depressed has floated. Can make the operator notice.

  Further, in the forklift 1 of the present embodiment, when the shift position of the shift lever 20 is in the neutral position, no power is transmitted to the drive wheels 13, so the oil from the cargo handling pump 42 is supplied to the hydraulic motor 48. By not prohibiting the supply, the cargo handling operation by the operator can be continued.

Therefore, when the shift position is at the neutral position, the operator does not have to interrupt the cargo handling operation, and therefore it is possible to prevent the work efficiency from being lowered.
Further, according to the forklift 1 of the present embodiment, even if the clutch 36 is in a half-clutch state, if the rotation speed of the engine 30 is less than a predetermined value, the rotating operation of the fork 11 is not prohibited, and therefore the vehicle runs at a low speed. However, the rotating work of the fork 11 can also be performed.

  In the first embodiment, the rotation attachment 12 corresponds to the cargo handling member, the hydraulic motor 48 corresponds to the driving means, the cargo handling pump 42 and the cargo handling hydraulic circuit 70 correspond to the cargo handling power transmission means, The automatic transmission 32 corresponds to the traveling system power transmission means. The inching switch 94 corresponds to a temperature rise detection unit, and the relays RY1, RY2, RY3, RY4 and the electromagnetic valve 74 correspond to a prohibition unit. Further, the shift switch 92 corresponds to the shift position detecting means, and the throttle switch 96 corresponds to the accelerator operation amount detecting means.

  Next, a forklift according to a second embodiment will be described with reference to FIG. FIG. 3 is an explanatory diagram illustrating the internal configuration of the forklift according to the second embodiment. Moreover, in FIG. 3, since the same code | symbol is attached | subjected about the component similar to the forklift 1 of 1st Embodiment, detailed description is abbreviate | omitted. This also applies to FIGS. 4 to 7 described later.

  Compared with the forklift 1 of the first embodiment, the forklift of the second embodiment is provided with a clutch pressure sensor 102 that detects the hydraulic pressure of the clutch 36 instead of the inching switch 94, regardless of the shift position of the shift lever 20. The electromagnetic valve 74 is driven when a predetermined clutch pressure is detected by the clutch pressure sensor 102 and the throttle switch 96 is turned on.

The effect similar to 1st Embodiment can be acquired also by such a forklift of 2nd Embodiment.
In the second embodiment, the clutch pressure sensor 102 corresponds to the temperature rise detection means.

Next, a forklift according to a third embodiment will be described with reference to FIG. FIG. 4 is an explanatory diagram illustrating the internal configuration of the forklift according to the third embodiment.
Compared with the forklift 1 of the first embodiment, the forklift of the third embodiment detects that the limiter 104 for limiting the maximum number of revolutions of the engine 30 and the rotation lever 19 are operated instead of the throttle switch 96. The rotation lever detection switch 106 is provided to operate the limiter 104 when the rotation lever 19 is operated. In the third embodiment, the limiter 104 limits the maximum rotational speed of the engine 30 to about 2/3 of the normal time.

  Further, the forklift of the third embodiment drives the solenoid valve 74 when the shift position of the shift lever 20 is in the forward position or the reverse position and the clutch 36 is in a fully connected state or a half-clutch state. Has been.

The effect similar to 1st Embodiment can be acquired also by the forklift of 3rd Embodiment as mentioned above.
In addition, according to the forklift of the third embodiment, the limiter 104 operates when the fork 11 is rotated by the operator, so that a large force is not suddenly applied to the rotation attachment 12. Therefore, safety can be ensured.

  In the forklift according to the third embodiment, the solenoid valve 74 is driven when the shift position of the shift lever 20 is the forward drive position or the reverse drive position without the throttle switch 96 and the inching switch 94 is turned off. However, similarly to the first embodiment, a throttle switch 96 may be provided, and the solenoid valve 74 may be driven when the throttle switch 96 is turned on. In the third embodiment, the rotation lever detection switch 106 corresponds to the cargo handling operation detection means, and the limiter 104 corresponds to the first rotation speed limiting means.

Next, a forklift according to a fourth embodiment will be described with reference to FIG. In addition, FIG. 5 is explanatory drawing explaining the internal structure of the forklift of 4th Embodiment.
Compared with the forklift 1 of the first embodiment, the forklift of the fourth embodiment is an oil that turns on when the oil temperature of the oil tank of the traveling pump 40 becomes a predetermined temperature or more, instead of the inching relay RY3 and the inching switch 94. The point that the temperature switch 108 is provided is different from the point that the limiter 104 is provided in place of the solenoid valve 74, and the limiter 104 is activated when the temperature of the oil tank of the traveling pump 40 exceeds a predetermined temperature. Has been. In the fourth embodiment, the limiter 104 is configured to limit the maximum rotational speed of the engine 30 to about 2/3 of the normal time, as in the third embodiment. The maximum number of revolutions of the engine 30 limited by the limiter 104 is any value as long as the oil temperature of the oil tank of the traveling pump 40 can be prevented from rising due to frictional heat of the clutch 36. It may be set to.

  For this reason, according to the forklift of the fourth embodiment, the maximum number of revolutions of the engine 30 limited by the limiter 104 is set so that the automatic transmission 32 is not affected by frictional heat even if the clutch 36 is in a half-clutch state, for example. By setting to this value, it is possible to suppress the oil temperature of the oil tank of the traveling pump 40 from rising due to the frictional heat of the clutch 36.

  Furthermore, according to the forklift of the fourth embodiment, even if the oil temperature switch 108 is turned on, the limiter 104 only limits the maximum number of revolutions of the engine 30, so that the fork 11 can be rotated while traveling at a low speed. You can also.

In the fourth embodiment, the oil temperature switch 108 corresponds to a temperature rise detection unit, and the limiter 104 corresponds to a second rotation speed limiting unit.
Next, a forklift according to a fifth embodiment will be described with reference to FIG. FIG. 6 is an explanatory diagram illustrating the internal configuration of the forklift according to the fifth embodiment.

  Compared with the forklift according to the fourth embodiment, the forklift according to the fifth embodiment includes an oil temperature sensor 110 that detects the oil temperature of the oil tank of the traveling pump 40 and an oil temperature sensor 110 instead of the oil temperature switch 108. The difference is that a controller 112 for operating the limiter 104 based on the detected value is provided by detecting the oil temperature signal of the oil pump and detecting the temperature increase rate of the oil temperature of the oil tank of the traveling pump 40 per unit time. Yes.

  The controller 112 is composed mainly of a microcomputer such as a CPU, RAM, ROM, etc., and determines whether or not the oil temperature of the oil tank after a predetermined time reaches a predetermined temperature based on the temperature increase rate detected from the oil temperature signal. The limiter is operated when it is determined that the predetermined temperature is reached.

For this reason, the same effect as that of the fourth embodiment can also be obtained by the forklift of the fifth embodiment.
In the fifth embodiment, the oil temperature sensor 110 and the controller 112 correspond to temperature rise detection means.

Next, a forklift according to a sixth embodiment will be described with reference to FIG. FIG. 7 is an explanatory diagram illustrating the internal configuration of the forklift according to the sixth embodiment.
Compared with the forklift according to the fourth embodiment, the forklift according to the sixth embodiment is provided with a rotation lever detection switch 106 instead of the oil temperature switch 108, and the limiter 104 is provided only when the rotation lever 19 is operated. It is made to operate.

  Also by the forklift according to the sixth embodiment, the same effects as those of the fourth and fifth embodiments can be obtained. However, in the forklift according to the sixth embodiment, the maximum number of revolutions of the engine 30 is limited only when the rotation lever 19 is operated. Therefore, the fourth and fifth embodiments are more effective. is there.

In the sixth embodiment, the rotation lever detection switch 106 corresponds to a temperature rise detection means and a cargo handling operation detection means.
As mentioned above, although embodiment of this invention was described, it cannot be overemphasized that this invention can take a various form.

  In the above embodiment, the inching switch 94, the clutch pressure sensor 102, and the like are used. However, the invention is not limited to this, and the clutch hydraulic line 52 is connected from the traveling pump 40 to the clutch hydraulic line 52 after the inching pedal 22 is operated and released. As long as it detects the temperature rise of the oil supplied to the clutch 36 via For example, a vehicle speed sensor that detects the vehicle speed of the forklift may be provided, and the electromagnetic valve 74 may be driven when the vehicle speed is detected by the vehicle speed sensor.

  In the first to third embodiments, the rotating operation of the fork 11 is prohibited by driving the electromagnetic valve 74. However, the rotation operation of the fork 11 is not limited to this. The 19 operation may be prohibited.

  Further, in the present embodiment, only the rotation work of the fork 11 is restricted or prohibited. However, the present invention is not limited to this, and the raising / lowering work and tilting work of the fork 11 may be restricted or prohibited.

1 is an overall view of a forklift according to a first embodiment. It is explanatory drawing explaining the internal structure of the forklift of the embodiment. It is explanatory drawing explaining the internal structure of the forklift of 2nd Embodiment. It is explanatory drawing explaining the internal structure of the forklift of 3rd Embodiment. It is explanatory drawing explaining the internal structure of the forklift of 4th Embodiment. It is explanatory drawing explaining the internal structure of the forklift of 5th Embodiment. It is explanatory drawing explaining the internal structure of the forklift of 6th Embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Forklift, 3 ... Elevator, 10 ... Mast, 11 ... Fork, 12 ... Attachment for rotation, 13 ... Front wheel, 14 ... Rear wheel, 17 ... Lift lever, 18 ... Tilt lever, 19 ... Rotation lever, DESCRIPTION OF SYMBOLS 20 ... Shift lever, 21 ... Accelerator pedal, 22 ... Inching pedal, 30 ... Engine, 32 ... Automatic transmission, 34 ... Torque converter, 36 ... Clutch, 40 ... Traveling pump, 42 ... Cargo handling pump, 44 ... Lift cylinder, 46 ... Tilt cylinder, 48 ... Hydraulic motor, 50 ... Travel hydraulic circuit, 52 ... Clutch hydraulic line, 54 ... Inching valve, 56 ... Electromagnetic valve for forward / reverse travel, 70 ... Hydraulic circuit for cargo handling, 72 ... Direction control unit, 74 ... Solenoid valve, 74a ... Coil, 84 ... Pipe for rotation, 86 ... Direction switching valve for rotation, 90 ... Solenoid valve drive circuit 92 ... Shift switch, 94 ... Inching switch, 96 ... Throttle switch, 98 ... Lamp, 100 ... In-vehicle battery, 102 ... Clutch pressure sensor, 104 ... Limiter, 106 ... Rotating lever detection switch, 108 ... Oil temperature switch, 110 ... Oil temperature sensor, 112 ... controller, RY1 ... forward relay, RY2 ... reverse relay, RY3 ... inching relay, RY4 ... solenoid valve relay.

Claims (10)

Engine,
Drive means for driving a cargo handling member for cargo handling work according to a command from an operator;
Cargo handling system power transmission means for transmitting power of the engine to the drive means;
Traveling system power transmission means for transmitting power of the engine to drive wheels via a torque converter and a transmission;
A clutch that is provided in a power transmission path from the torque converter to the drive wheel and that connects the power transmission path by receiving hydraulic pressure from a hydraulic source that generates hydraulic pressure by rotation of the engine;
An inching valve that is provided in a hydraulic path for transmitting hydraulic pressure from the hydraulic pressure source to the clutch, and that reduces the hydraulic pressure transmitted to the clutch;
Inching in which the inching valve is operated in accordance with a stepping operation by an operator, and a brake pedal for applying braking force to the wheel is interlocked in an interlocking section from a position where the operator depresses by a predetermined amount to a position where it is fully depressed. Pedal,
In vehicles equipped with
A temperature rise detecting means for detecting a temperature rise of oil supplied from the hydraulic pressure source to the clutch via the hydraulic pressure path when the inching pedal is depressed;
A prohibiting means for prohibiting transmission of power from the engine to the driving means when the temperature rise of the oil is detected by the temperature rise detecting means;
A vehicle characterized by comprising: Shift position detecting means for detecting a shift position of the transmission,
2. The vehicle according to claim 1, wherein the prohibiting unit does not prohibit transmission of power to the driving unit when the shift position detected by the shift position detecting unit is a neutral position. . An accelerator operation amount detection means for detecting an accelerator operation amount of the engine;
The prohibiting means does not prohibit transmission of power to the driving means when the accelerator operation amount detected by the accelerator operation amount detecting means is less than a predetermined value. Item 4. The vehicle according to item 2. A cargo handling operation detecting means for detecting that a driving command for the cargo handling member is input;
A first engine speed limiter configured to limit the maximum engine speed to a first set value less than an upper limit when the cargo handling operation detection unit detects that a driving command for the material handling member has been input; ,
The vehicle according to any one of claims 1 to 3, further comprising: Engine,
Drive means for driving a cargo handling member for cargo handling work according to a command from an operator;
Cargo handling system power transmission means for transmitting power of the engine to the drive means;
Traveling system power transmission means for transmitting power of the engine to drive wheels via a torque converter and a transmission;
A clutch that is provided in a power transmission path from the torque converter to the drive wheel and that connects the power transmission path by receiving hydraulic pressure from a hydraulic source that generates hydraulic pressure by rotation of the engine;
An inching valve that is provided in a hydraulic path for transmitting hydraulic pressure from the hydraulic pressure source to the clutch, and that reduces the hydraulic pressure transmitted to the clutch;
Inching in which the inching valve is operated in accordance with a stepping operation by an operator, and a brake pedal for applying braking force to the wheel is interlocked in an interlocking section from a position where the operator depresses by a predetermined amount to a position where it is fully depressed. Pedal,
In vehicles equipped with
A temperature rise detecting means for detecting a temperature rise of oil supplied from the hydraulic pressure source to the clutch via the hydraulic pressure path when the inching pedal is depressed;
A second engine speed limiter configured to limit the maximum engine speed to a second set value less than an upper limit when the temperature increase of the oil is detected by the temperature increase detector;
A vehicle characterized by comprising: Shift position detecting means for detecting a shift position of the transmission,
The limiting means does not limit the maximum rotational speed of the engine to a predetermined value less than an upper limit value when the shift position detected by the shift position detecting means is a neutral position. 5. The vehicle according to 5. A cargo handling operation detecting means for detecting that a driving command for the cargo handling member is input;
The second rotation speed limiting means limits the maximum rotation speed of the engine even when it is detected by the cargo handling operation detection means that a driving command for the cargo handling member is input. The vehicle according to claim 5 or claim 6.   The vehicle according to any one of claims 1 to 7, wherein the temperature rise detection means detects a temperature rise of the oil based on an operation amount of the inching pedal.   The vehicle according to any one of claims 1 to 7, wherein the temperature rise detection means detects a temperature rise of the oil based on a hydraulic pressure transmitted from the hydraulic pressure source to the clutch.   The vehicle according to any one of claims 1 to 7, wherein the temperature rise detection means detects a temperature rise of the oil based on an oil temperature of the hydraulic pressure source.

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