JP2016019355A - Control device of traction motor for forklift - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device of a traction motor for a forklift, which can make the forklift carry out energy saving operation such that the forklift does not exceed a prescribed maximum speed, while suppressing deterioration of work efficiency.SOLUTION: A control device 30 of a traction motor for a forklift comprises an inverter 40 and a controller 60. A microcomputer 61 of the controller 60 sets a first threshold as the maximum speed in an initial acceleration region of the forklift. The microcomputer 61, when determining that a running time of the forklift exceeds an intermediate travel region which is set following to the initial acceleration region and is longer than the initial acceleration region, sets as the maximum speed a second threshold larger than the first threshold.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a control device for a forklift travel motor.

  In a battery forklift that is an industrial vehicle having a travel motor, various speed limit controls are performed. For example, Patent Literature 1 discloses an acceleration limiting technique that reduces a shock at the time of starting by gradual acceleration at the time of starting. By the way, in recent years, forklifts as well as passenger cars, energy-saving operation such as eco mode is desired. For example, in speed limit control that limits the output of a motor so that the vehicle does not exceed a predetermined maximum speed, In the mode, the maximum speed limit control for limiting the maximum speed to be low is known.

JP 2011-94451 A

However, simply limiting the maximum speed to a low value causes a new problem that the working efficiency of the forklift deteriorates.
The objective of this invention is providing the control apparatus of the traveling motor for forklifts which can be made to perform an energy-saving operation so that the forklift may not exceed the predetermined maximum speed, suppressing the deterioration of work efficiency.

  In the first aspect of the present invention, the inverter that converts the DC power into the AC power and supplies the AC power to the traveling motor of the vehicle connected to the output side, and the forklift does not exceed a predetermined maximum speed. A control unit that controls output to the travel motor, the control unit configured to set a first threshold value as a maximum speed in the initial acceleration region of the forklift, and a travel time of the forklift Second threshold value setting means for setting a second threshold value that is larger than the first threshold value as a maximum speed when it is determined that an intermediate travel region longer than the initial acceleration region set subsequent to the initial acceleration region is exceeded; The gist is to have.

  According to the first aspect of the present invention, the control unit controls the output to the travel motor so that the forklift does not exceed the predetermined maximum speed. At this time, in the first threshold value setting means, the first threshold value is set as the maximum speed in the initial acceleration region of the forklift. Further, when the second threshold setting means determines that the travel time of the forklift has exceeded an intermediate travel region that is longer than the initial acceleration region that is set following the initial acceleration region, the second speed that is larger than the first threshold as the maximum speed. Is set. Therefore, it is possible to make it difficult to affect the efficiency of short-distance work and the efficiency of long-distance work. As a result, the energy-saving operation can be performed so that the forklift does not exceed the predetermined maximum speed while suppressing the deterioration of work efficiency.

  According to a second aspect of the present invention, in the control device for a forklift travel motor according to the first aspect, the control unit is a third threshold value setting means for setting a third threshold value as the maximum speed in the intermediate travel region. It is good to have further.

  The forklift travel motor control device according to claim 2, wherein the third threshold value setting means performs linear interpolation between the first threshold value and the second threshold value. Thus, the third threshold value may be set.

  According to the present invention, an energy-saving operation can be performed so that the forklift does not exceed a predetermined maximum speed while suppressing deterioration in work efficiency.

The schematic side view of the forklift in an embodiment. The circuit diagram of the control apparatus of the forklift travel motor. Explanatory drawing which shows the use frequency with respect to a travel distance. (A), (b) is explanatory drawing for demonstrating speed limit control. (A), (b) is explanatory drawing for demonstrating speed limit control. (A), (b) is explanatory drawing for demonstrating the speed limit control for a comparison. (A), (b) is explanatory drawing for demonstrating speed limit control. (A), (b) is explanatory drawing for demonstrating speed limit control of another example. (A), (b) is explanatory drawing for demonstrating speed limit control of another example. (A), (b) is explanatory drawing for demonstrating speed limit control.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, an embodiment of the invention will be described with reference to the drawings.
As shown in FIG. 1, the forklift 10 is a battery forklift, and is a forklift that performs conveyance and cargo handling work with an electric motor. Drive wheels (front wheels) 12 a are provided at the front lower part of the vehicle body 11 of the forklift 10, and steering wheels (rear wheels) 12 b are provided at the rear lower part of the vehicle body 11. A cargo handling device 13 is provided at the front of the vehicle body 11.

  A mast 14 constituting the cargo handling device 13 is erected on the front portion of the vehicle body 11. The mast 14 includes a pair of left and right outer masts 14a supported so as to be tiltable back and forth with respect to the vehicle body 11, and an inner mast 14b that slides up and down. A lift cylinder 15 is disposed at the rear of each outer mast 14a. A lift bracket 17 having a fork 16 is supported inside the inner mast 14b so as to be movable up and down. Then, the fork 16 is lifted and lowered together with the lift bracket 17 by the expansion and contraction operation of the lift cylinder 15.

  The pair of left and right tilt cylinders 18 is pivotally connected to the vehicle body (body frame) 11 at the base end side, and is pivotally connected to the side surface of the outer mast 14a. The mast 14 tilts back and forth as the tilt cylinder 18 is driven to expand and contract.

  The cab R is equipped with a handle 19, a lift lever 20 and a tilt lever 21 on the front side thereof. The lift lever 20 is a lever for moving the fork 16 up and down, and the tilt lever 21 is a lever for tilting the mast 14 in the front-rear direction. An accelerator pedal 22 is provided on the floor of the driver's seat, and the vehicle speed is set according to the amount of operation of the accelerator pedal 22 (the amount of pedal depression).

  The vehicle body 11 is equipped with a battery 23, a traveling motor (traveling electric motor) 24, and a cargo handling motor (loading electric motor) 25. The traveling motor 24 is driven by the battery 23 so that the driving wheel 12a is driven. Specifically, the output shaft of the travel motor 24 is connected to the rotation shaft of the drive wheel 12a via a speed reducer. When the output shaft is rotated by the drive of the travel motor 24, the rotation shaft of the drive wheel 12a is rotated along with the rotation. The drive wheel 12a is driven by rotation.

  Further, the cargo handling motor 25 is driven by the battery 23, and a hydraulic pump (not shown) is driven by the driving of the cargo handling motor 25. Based on the driving of the hydraulic pump, the lift cylinder 15 and the tilt cylinder 18 are expanded and contracted so that the fork 16 can be moved up and down and tilted.

  As shown in FIG. 2, the control device 30 for the travel motor 24 is mounted on the forklift 10. The control device 30 includes an inverter 40, a drive circuit 50, and a controller 60. The inverter 40 includes a plurality of bridge-connected switching elements S1 to S6 and a capacitor 80, and a battery 23 as a DC power source is connected to the input side.

  A travel motor 24 is connected to the output side of the inverter 40. A three-phase AC motor is used as the travel motor 24. The traveling motor 24 has windings 24 a, 24 b, 24 c, and the windings 24 a, 24 b, 24 c of each phase of the traveling motor 24 are connected to the output side of the inverter 40.

  The bridge circuit of the inverter 40 is provided with six switching elements S1 to S6. A power MOSFET is used for each of the switching elements S1 to S6. An IGBT (insulated gate bipolar transistor) may be used as the switching element. Feedback diodes D1 to D6 are connected in reverse parallel to the switching elements S1 to S6, respectively.

  In the bridge circuit of the inverter 40, the first and second switching elements S1 and S2, the third and fourth switching elements S3 and S4, and the fifth and sixth switching elements S5 and S6 are connected in series, respectively. . The first, third, and fifth switching elements S1, S3, and S5 are connected to the positive terminal side of the battery 23 as a DC power source, and the second, fourth, and sixth switching elements S2, S4, and S6 are connected. Is connected to the negative terminal side of the battery 23.

  The connection point between the switching elements S1 and S2 constituting the upper and lower arms for the U phase is connected to the U phase terminal of the traveling motor 24, and the connection point between the switching elements S3 and S4 constituting the upper and lower arms for the V phase. Is connected to the V-phase terminal of the traveling motor 24, and the connection point between the switching elements S5 and S6 constituting the upper and lower arms for the W-phase is connected to the W-phase terminal of the traveling motor 24, respectively. Then, the control device 30 of the traveling motor 24 supplies an alternating current to the windings of each phase of the traveling motor 24 to drive the traveling motor 24.

The rated voltage of the battery 23 is 48 volts, for example. Examples of the battery (secondary battery) 23 include a lead storage battery, a lithium ion battery, and a nickel metal hydride battery.
Current sensors 70 and 71 are provided between the inverter 40 and the traveling motor 24. Current sensors 70 and 71 detect current values of currents Iu and Iw of two phases (U-phase and W-phase in this embodiment) of three-phase currents Iu, Iv, and Iw supplied to traveling motor 24.

  The capacitor 80 is an electrolytic capacitor and is connected in parallel with the battery 23. The first, third, and fifth switching elements S1, S3, and S5 are connected to the positive terminal side of the capacitor 80, and the second, fourth, and sixth switching elements S2, S4, and S6 are the negative terminal side of the capacitor 80. It is connected to the.

  The controller 60 has a microcomputer 61 and a memory 62. The memory 62 stores various control programs necessary for driving the traveling motor 24 and various data and maps necessary for the execution thereof. The control program includes a control program for rotationally driving the traveling motor 24, a control program for speed limitation, and the like.

  In FIG. 2, the controller 60 is connected to the gates of the switching elements S <b> 1 to S <b> 6 of the inverter 40 through the drive circuit 50. Current sensors 70 and 71 are connected to the controller 60. Then, the microcomputer 61 of the controller 60 sends a control signal for controlling the traveling motor 24 to the target output based on the detection signals of the sensors 70 and 71 to the switching elements S1 to S6 via the drive circuit 50. The output of the inverter 40 is controlled. Then, the inverter 40 converts the direct current supplied from the battery 23 into a three-phase alternating current having an appropriate frequency and outputs it to the traveling motor 24. That is, the inverter 40 converts DC power into AC power and supplies AC power to the vehicle travel motor 24 connected to the output side.

  A vehicle control ECU 90 is mounted on the vehicle. The vehicle control ECU 90 includes a microcomputer and the like. The vehicle control ECU 90 controls an operation of the vehicle by inputting an operation signal output from an operation sensor (not shown) in accordance with an operation by the operator.

  The controller 60 is connected to the vehicle control ECU 90, and the microcomputer 61 can detect various operations. Then, the microcomputer 61 of the controller 60 adjusts the vehicle speed by controlling the traveling motor 24 so that the rotational speed of the traveling motor 24 corresponds to the operation amount of the accelerator pedal 22. Further, the microcomputer 61 of the controller 60 detects the voltage (battery voltage) Vb of the battery 23.

  The controller 60 and the drive circuit 50 of the control device 30 are mounted on the control board 110. Switching elements S1 to S6 and feedback diodes D1 to D6 of the inverter 40 are mounted on the main circuit board 100.

FIG. 3 shows the relationship between the travel distance of the forklift 10 and the usage frequency. In FIG. 3, the horizontal axis represents the travel distance and the vertical axis represents the frequency of use.
In FIG. 3, it can be seen that the frequency of use is high when a work with a short travel distance is performed (for example, a work that travels 10 m) and when a work with a long travel distance is performed (for example, a work that travels 100 m). That is, it can be seen that the forklift 10 is often used for the short distance work Ws and the long distance work Wg. In addition, a region between a short-distance work area and a long-distance work area corresponding to a travel distance with high use frequency is an area corresponding to a travel distance with low use frequency.

The memory 62 of the controller 60 stores threshold values v1 and v2 that define the maximum speed for performing the speed limit control shown in FIG.
In FIG. 4A, the horizontal axis represents time and the vertical axis represents the vehicle speed limit. A first threshold value v1 and a second threshold value v2 are stored as speed limits, and the second threshold value v2 is a value larger than the first threshold value v1. For example, the first threshold value v1 is 45 km / h, and the second threshold value v2 is 50 km / h.

  As shown in FIG. 4B, when the accelerator pedal 22 is operated by a predetermined amount θ1 from the non-operating state, the maximum speed is regulated by the first threshold value v1 in the initial acceleration region of the forklift. The initial acceleration region is a region from the start of frequent use to the predetermined distance.

  The intermediate travel area is an area corresponding to a travel distance that is less frequently used. The intermediate travel area is set following the initial acceleration area and is longer than the initial acceleration area. When the intermediate travel area is exceeded, the maximum speed is regulated by the second threshold v2.

  As described above, the first threshold value v1 is prepared as the maximum speed in the initial acceleration region of the forklift, and the second threshold value v2 is prepared as the maximum speed in the region exceeding the intermediate traveling region. That is, as compared with the case where only the threshold value v2 is prepared as a comparative example, in the present embodiment, the first threshold value v1 and the second threshold value v2 are prepared.

  In the following description, as in FIG. 4B, FIGS. 5B, 6B, 7B, 8B, 9B, and 10B are used. ) Also assumes that the accelerator pedal 22 is operated by a predetermined amount θ1 from the non-operating state.

Next, the operation of the control device 30 for the travel motor 24 of the forklift 10 will be described.
The controller 60 controls the output to the traveling motor 24 so that the forklift does not exceed a predetermined maximum speed. At this time, the following processing is executed.

In FIG. 5A, the horizontal axis represents time, and the vertical axis represents the actual speed (actual speed) of the vehicle.
The microcomputer 61 sets the first threshold value v1 as the maximum speed in the initial acceleration region of the forklift up to the timing t2 with the accelerator operation at the timing t1 in FIG. Therefore, in the initial acceleration region, the actual speed increases at a constant inclination (acceleration) α1 up to the first threshold value v1. This acceleration α1 is the same as the acceleration α1 in the comparative example shown in FIG. 6, and the acceleration α1 is not changed. In the initial acceleration region, the short distance work Ws shown in FIG. 3 is performed. The time in the initial acceleration region, that is, the time from t1 to t2 is, for example, 5 seconds.

Therefore, in contrast to the comparative example shown in FIG. 6, this embodiment shown in FIG. 5 does not affect the efficiency of the short-distance work Ws.
Thereafter, since the intermediate travel region from the timing t2 to the timing t3 in FIG. 5A corresponds to a travel distance that is less frequently used, the actual speed is kept at the first threshold value v1. Become. The time in the intermediate travel area, that is, the time from t2 to t3 is, for example, 30 seconds.

  If the microcomputer 61 determines that the forklift traveling time has exceeded the intermediate traveling region at the timing t3 in FIG. 5A, the microcomputer 61 sets the second threshold v2 as the maximum speed. Therefore, when the intermediate travel region is exceeded, the actual speed increases to the second threshold value v2. After the actual speed reaches the second threshold value v2, the second threshold value v2 is maintained, and the long distance work Wg in FIG. 3 is performed after the timing t3 in FIG. Therefore, in contrast to the comparative example shown in FIG. 6, in the present embodiment shown in FIG. 5, the maximum speed (v2) is not changed and the influence on the work efficiency is small.

  In the present embodiment shown in FIG. 5 in comparison with the comparative example shown in FIG. 6, energy can be saved in the area A1 hatched in FIG. 7A. The area A1 includes a speed profile L3b (see FIG. 6A), a speed profile L2c (see FIG. 5A), a speed profile L2b (see FIG. 5A), and a speed profile L3a (see FIG. 6A). ). Thereby, energy saving is achieved by the area A1. As a result, energy-saving operation can be realized in a manner that has less influence on work efficiency.

According to the above embodiment, the following effects can be obtained.
(1) The configuration of the control device 30 for the forklift travel motor includes an inverter 40 and a controller 60. The controller 60 as the control unit sets the first threshold value v1 as the maximum speed in the initial acceleration region of the forklift. It has the microcomputer 61 as a 1st threshold value setting means. If the controller 60 determines that the travel time of the forklift has exceeded the intermediate travel region that is longer than the initial acceleration region that is set following the initial acceleration region, the second threshold v2 that is greater than the first threshold v1 as the maximum speed. Has a microcomputer 61 as a second threshold value setting means for setting. Then, as shown in FIG. 5 (a), the output to the travel motor 24 is controlled so that the forklift does not exceed the predetermined maximum speed.

  As a result, the efficiency of short-distance work and the efficiency of long-distance work can be made less likely to be affected, and energy-saving operation can be performed so that the forklift does not exceed the specified maximum speed while suppressing deterioration of work efficiency. it can.

The embodiment is not limited to the above, and may be embodied as follows, for example.
-Instead of FIG. 4, you may make it show in FIG. In FIG. 8, the third threshold value as the maximum speed in the intermediate travel region is linearly interpolated between the first threshold value v1 and the second threshold value v2. That is, the restriction is applied with a value that approximates a straight line between the first threshold value v1 at the start of the intermediate travel and the second threshold value v2 at the end of the intermediate travel.

  Then, as shown in FIG. 9B, in the initial acceleration region of the forklift up to the timing t2 with the accelerator operation at the timing t1, the actual speed is constant (acceleration) α1 up to the first threshold v1. After the initial acceleration region ends and reaches the first threshold value v1 at the timing t2 in FIG. 9A, the speed gradually increases to the second threshold value v2 until the intermediate traveling region is exceeded at the timing t3. Goes up.

  Therefore, in contrast to the comparative example shown in FIG. 6, in the present embodiment shown in FIG. 9A, energy can be saved in the area A2 hatched in FIG. 10A. The area A2 is an area surrounded by a speed profile L3b (see FIG. 6A), a speed profile L4b (see FIG. 9A), and a speed profile L3a (see FIG. 6A). Thereby, energy saving is achieved by the area A2. As a result, both work efficiency and energy saving can be achieved.

With the configuration described with reference to FIGS. 8 and 9, the following effects can be obtained.
(2) The controller 60 as the control unit further includes a microcomputer 61 as third threshold setting means for setting a third threshold as the maximum speed in the intermediate travel region. Therefore, it is practical.

(3) In particular, the microcomputer 61 sets the third threshold value by linearly interpolating between the first threshold value v1 and the second threshold value v2. Therefore, it is practical.
In this case, the third threshold value is set by linear interpolation between the first threshold value v1 and the second threshold value v2. However, the present invention is not limited to this.

  The first threshold v1 is, for example, 45 km / h and the second threshold v2 is, for example, 50 km / h. However, the first threshold and the second threshold may be set to predetermined values.

  DESCRIPTION OF SYMBOLS 10 ... Forklift, 24 ... Traveling motor, 30 ... Control apparatus, 40 ... Inverter, 60 ... Controller, 61 ... Microcomputer, v1 ... 1st threshold value, v2 ... 2nd threshold value.

Claims (3)

An inverter that converts direct current power into alternating current power and supplies alternating current power to a vehicle travel motor connected to the output side;
A control unit for controlling the output to the traveling motor so that the forklift does not exceed a predetermined maximum speed;
With
The controller is
A first threshold value setting means for setting a first threshold value as a maximum speed in the initial acceleration region of the forklift;
When it is determined that the travel time of the forklift has exceeded an intermediate travel region that is longer than the initial acceleration region that is set following the initial acceleration region, a second threshold that is larger than the first threshold is set as the maximum speed. Threshold setting means,
A control device for a forklift travel motor. The controller is
The forklift travel motor control device according to claim 1, further comprising third threshold setting means for setting a third threshold as the maximum speed in the intermediate travel region.   The forklift according to claim 2, wherein the third threshold value setting means sets the third threshold value by linearly interpolating between the first threshold value and the second threshold value. Control device for travel motor.