JP6887285B2 - Work vehicle travel control device - Google Patents

Description

The present invention relates to a traveling control device for a work vehicle in which an induction motor for traveling is controlled by an inverter.

As one of the typical examples of work vehicles, for example, self-propelled work vehicles used for transportation work and interior work in buildings such as factories and warehouses are generally relatively equipped with wheels on the front, rear, left and right sides. It is configured to include a small traveling body, an elevating device provided on the traveling body so as to be able to move up and down, and a workbench for boarding a worker provided at the tip of the elevating device. By using the operating device provided on the workbench to perform running operations and elevating / lowering operations, the worker boarding the workbench can move the traveling body to an arbitrary work position and move the workbench to a desired high position. The work can be performed by moving it up and down (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2007-9439

In the above-mentioned work vehicles (especially indoor work vehicles), in order to prevent exhaust gas and noise, the battery built in the traveling body is used as a power source, and the DC power of this battery is converted into AC power by an inverter. The induction motors are driven by supplying the induction motors provided on the left and right drive wheels. Here, since the capacity of the battery is limited and it is necessary to spend a predetermined time at a predetermined place for charging the battery, it is difficult to charge the battery once the work is started. Therefore, in recent years, it has become an issue to reduce the power consumption of the battery without deteriorating the running performance of the work vehicle.

The present invention has been made in view of such a problem, and an object of the present invention is to provide a travel control device for a work vehicle capable of reducing power consumption while maintaining traveling performance.

In order to solve the above problems, the travel control device for a work vehicle according to the present invention is provided with a pair of left and right wheels on the front and rear of the vehicle body, and the pair of left and right wheels on either the front side or the rear side are drive wheels. An induction motor that drives the drive wheels, a rotation detection means that detects the actual rotation speed of the induction motor, a battery for supplying power to the induction motor, and a travel command value according to an operation by the operator. According to the operating means for setting, the inverter that converts the DC power from the battery into AC power and supplies it to the induction motor to drive the drive wheels, and the command rotation speed set based on the travel command value. The traveling control means for controlling the operation of the inverter so that the AC power of the command frequency is supplied to the induction motor is provided, and the traveling control means rotates between the commanded rotation speed and the actual rotation speed. It is configured to correct the voltage value of the AC power supplied to the induction motor based on the difference between the speed difference and the preset reference value.

Then, in the travel control device of the work vehicle having the above configuration, the travel control means so as to maintain the rotation speed difference at the specified value when the rotation speed difference exceeds a preset specified value. It is characterized in that it is configured to correct the command rotation speed.

Further, the traveling control device of the work vehicle having the above configuration includes an inclination angle detecting means for detecting the inclination angle of the traveling body in the front-rear direction with respect to the horizontal plane, and the induction motor based on the rotation speed difference and the inclination angle. It is supplied to the induction motor based on the first voltage control process for controlling the voltage value of the AC power supplied to the device, the rotation speed difference, and at least one of the command rotation speed and the actual rotation speed. It has a second voltage control process for controlling the voltage value of AC power, and the travel control means is configured to selectively execute the first voltage control process and the second voltage control process. preferable.

Further, in the traveling control device of the work vehicle having the above configuration, the larger voltage value of the voltage value calculated by the first voltage control process and the voltage value calculated by the second voltage control process is set. It is preferable that the voltage value of the AC power supplied to the induction motor is determined.

Further, in the traveling control device of the work vehicle having the above configuration, in the second voltage control process, the actual rotation speed is smaller than a predetermined predetermined rotation speed set in advance, and between the command rotation speed and the actual rotation speed. When there is a difference in rotation speed, it is preferable to increase the voltage value of the AC power supplied to the induction motor according to the magnitude of the difference in rotation speed.

According to the traveling control device of the work vehicle according to the present invention, the rotation speed difference between the command rotation speed set by the operation of the operation means and the actual rotation speed detected by the rotation detection means is calculated, and the rotation speed difference is calculated. By correcting the voltage value of the AC power supplied to the induction motor according to the difference between the above and the preset reference value, the induction motor can always be driven at an efficient operating point. It is possible to reduce the power consumption of the battery by suppressing the heat generation of the induction motor and the inverter while maintaining the running performance.

Further, in the traveling control device of the work vehicle having the above configuration, when the rotation speed difference between the command rotation speed and the actual rotation speed exceeds a preset predetermined value, the command rotation speed of the induction motor is as in the conventional case. The characteristics of the induction motor were maximized by performing feedback control that corrects the commanded rotation speed so that the difference in rotation speed is maintained at the specified value without reducing the rotation speed to the point where the maximum torque can be output. In this way, it is possible to improve the running performance of the work vehicle.

Further, in the travel control device of the work vehicle having the above configuration, the first voltage control process and the second voltage control process, which have different voltage control parameters from each other, are selectively executed, so that the traveling state of the work vehicle can be adjusted. As the voltage control, it is possible to establish a voltage control suitable for the road surface condition.

Further, in the travel control device of the work vehicle having the above configuration, the voltage value calculated by the first voltage control process and the voltage value calculated by the second voltage control process are compared, and the larger voltage is compared. By determining the value as the voltage value of the AC power supplied to the induction motor, it is possible to supply the optimum output voltage to the induction motor according to the running state of the work vehicle.

Further, in the traveling control device of the work vehicle having the above configuration, the actual rotation speed follows the command rotation speed even though the work vehicle cannot move on the step on the road surface and the operator increases the amount of operation. If this is not the case (when the actual rotation speed is small and the rotation speed difference is large), voltage correction that reflects the operator's operation intention is performed (command voltage value is set according to the above operation amount). (To increase), the work vehicle will be able to properly overcome the step under the high output torque, and it will be possible to further improve the running performance of the work vehicle.

It is a perspective view of the aerial work platform which concerns on this embodiment. It is a block diagram which shows the control composition in the said aerial work platform. It is a top view which shows the structure of the steering apparatus in the said aerial work platform. It is a schematic diagram which shows the relationship between the extension amount of a steering cylinder and the rudder angle of a front wheel in the said work vehicle in a high place, (A) is a state where the extension amount of a steering cylinder is zero, (B) is the extension amount of a steering cylinder A positive value state, (C) indicates a state in which the extension amount of the steering cylinder is a negative value. It is a perspective view of the operation device provided in the said aerial work platform. It is a schematic diagram which shows the movement of a wheel according to the operation state of the steering dial in the aerial work platform, (A) is a normal turning center, (B) is a turning center when turning right at the maximum steering angle, ( C) indicates the turning center when turning left at the maximum steering angle. It is a figure which shows typically the rotation speed control table in this embodiment. It is a torque diagram which shows the relationship between the rotation speed (frequency) of the traveling motor provided in the aerial work platform and the output torque. It is a figure which shows typically the V / f pattern in this embodiment. It is a figure which shows typically the 1st voltage control table in this embodiment. It is a figure which shows typically the 2nd voltage control table in this embodiment. It is a figure which shows typically the 3rd voltage control table in this embodiment. It is a figure which shows typically the 4th voltage control table in this embodiment. It is a figure which shows typically the 5th voltage control table in this embodiment. It is a flowchart which shows the procedure of the traveling control processing in the said aerial work platform.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows an aerial work platform 1 to which the traveling control device according to the present invention is applied. First, the overall configuration of the aerial work platform 1 will be described with reference to this figure.

The aerial work platform 1 is a so-called vertical elevating type aerial work platform, and is provided with a traveling body 10 capable of traveling with four tire wheels 11 provided on the front, rear, left and right sides, and an upper portion of the traveling body 10. It is mainly composed of a scissors link mechanism 20 and a workbench 30 for boarding an operator supported by the scissors link mechanism 20.

Of the front, rear, left and right tire wheels 11 provided on the traveling body 10, a pair of left and right tire wheels 11a and 11b arranged on the front side of the traveling body 10 (hereinafter, both "left front wheel 11a" and "right front wheel 11b"). Is configured as a drive wheel and a steering wheel. Hereinafter, for convenience of explanation, the front wheels may be referred to as "driving wheels" or "steering wheels". The traveling body 10 has two traveling motors 12a and 12b (see FIG. 2) that independently drive the left and right front wheels 11a and 11b, and the traveling motors 12a and 12b drive the front wheels 11a and 11b, respectively. At the same time, by steering the front wheels 11a and 11b via a steering device described later, the vehicle can travel to a desired position. A so-called negative brake 14 that brake-locks the rotating shaft of the motor is integrally attached to these traveling motors 12a and 12b. On the other hand, the pair of left and right tire wheels 11c and 11d (hereinafter, also referred to as "left rear wheel 11c" and "right rear wheel 11d") arranged on the rear side of the traveling body 10 are non-driving wheels and are traveling bodies. It is rotatably attached to a shaft 19 (see FIG. 3) projecting from each of the left and right side surfaces of the 10.

In the scissors link mechanism 20, a plurality of sets of two link members 20a, which are pivotally connected by a pivot pin 20b at the center of each other to form an X shape, are formed in the vertical direction and the horizontal direction (the vehicle width direction of the traveling body 10). It has an arranged configuration. Of the two link members 20a, the lower end of the link member 20a located on the upper side and the upper end of the link member 20a located on the lower side are pivotally connected by a pivot pin 20b. The pivot portion is connected to a connecting rod 20d extending in the left-right direction (vehicle width direction of the traveling body 10). Of the lowermost link members 20a constituting the scissors link mechanism 20, the lower end of the lowermost link member 20a on the front side of the traveling body 10 is pivotally connected to the upper part of the traveling body 10, and is the most constituting the scissors link mechanism 20. The lower end of the lower link member 20a on the rear side of the traveling body 10 is connected to a roller 20e that rolls on the upper surface of a rail (not shown) provided on the upper part of the traveling body 10. .. Further, among the uppermost link members 20a constituting the scissors link mechanism 20, the upper end portion of the uppermost link member 20a on the front side of the traveling body 10 is pivotally connected to the lower part of the work table 30 to form the scissors link mechanism 20. The upper end of the uppermost link member 20a on the rear side of the traveling body 10 is connected to a roller 20f that rolls on the lower surface of a rail (not shown) provided on the lower surface of the work table 30. ing. The scissors link mechanism 20 having such a configuration is vertically expanded and contracted by an elevating cylinder (hydraulic cylinder) 21 straddled between the link mechanism 20 and the traveling body 10, and is arranged above the scissors link mechanism 20. The workbench 30 can be moved up and down.

On the workbench 30, an operation device 40 operated by the on-board worker is attached to a handrail 31 installed to prevent the worker from falling. The operating device 40 operates the traveling operation lever 41 for switching the start / stop and forward / backward movement of the traveling body 10 and steering the traveling body 10 (that is, steering the front wheels 11a and 11b which are steering wheels). A steering dial 42 for this purpose, an elevating operation lever 43 for elevating and lowering the work table 30, and the like are provided. The worker on the workbench 30 operates the traveling operation lever 41, the steering dial 42, the elevating operation lever 43, and the like to travel, steer, and elevate the workbench 30 to perform arbitrary work. You can move to the position and perform the required work.

As shown in FIG. 3, the left and right steering wheels (front wheels 11a and 11b) and the steering dial 42 are interlocked and connected via a steering device. This steering device drives a steering mechanism 13 connected to the front wheels 11a and 11b and the steering mechanism 13 to drive the steering angles γ _L and γ _{R of} the front wheels 11a and 11b (front wheels with respect to the front and rear central axes of the traveling body 10). A steering cylinder (hydraulic cylinder) 17 that changes the deflection angles of the front wheels 11a and 11b, a steering angle detector (for example, a potentiometer) 61 that detects the steering angles of the front wheels 11a and 11b, and a target steering angle of the front wheels 11a and 11b are set. It is configured to include the above-mentioned rudder angle dial 42 and a controller 50 that controls the operation of the steering cylinder 17 in response to the operation of the rudder angle dial 42.

As shown in FIG. 3, the steering mechanism 13 has a pair of knuckle arms 14 that swingably support the front wheels 11a and 11b around the kingpin shaft 15, and a pair of connecting pins P1 to the pair of knuckle arms 14. It is configured to have a tie rod 16 connected to the tie rod 16. Although omitted in FIG. 3, the steering angle detector 61 is attached to the knuckle arm 14 and detects the steering angles of the front wheels 11a and 11b from the rotation angle centered on the kingpin shaft 15. One end of the steering cylinder 17 is connected to the left knuckle arm 14 via the connecting pin P2, and the other end is connected to the traveling body 10 via the connecting pin P3.

Therefore, in the above steering device, by expanding and contracting the steering cylinder 17, the left front wheel 11a is swung around the left kingpin shaft 15, and the right front wheel 11b is moved to the right kingpin shaft via the tie rod 16. The steering angles of the front wheels (steering wheels) 11a and 11b can be changed by swinging around 15 at the same time as the left front wheel 11a and in the same direction. That is, the left and right front wheels 11a and 11b can be deflected to the right by extending the steering cylinder 17, and the left and right front wheels 11a and 11b can be deflected to the left by contracting the steering cylinder 17. it can.

At this time, the left and right front wheels 11a and 11b are set so that the steering angle of the left front wheel 11a and the steering angle of the right front wheel 11b are different when the traveling body 10 is turned by the steering mechanism 13. That is, of the pair of left and right front wheels 11a and 11b, the steering angle of the inner ring is set to be always larger than the steering angle of the outer ring at a constant ratio. The relationship between the rudder angles will be specifically described with reference to FIG. In the following, the sign of the steering angle when the left and right front wheels 11a and 11b are deflected to the right is defined as "positive", and the sign of the steering angle when the left and right front wheels 11a and 11b are deflected to the left is defined as "positive". Defined as "negative". First, as shown in FIG. 4A, when the expansion / contraction amount Δ of the steering cylinder 17 is zero (Δ = 0), the steering angles γ _L and γ _R of the left and right front wheels 11a and 11b are both zero. As shown in FIG. 4B, when the expansion / contraction amount Δ of the steering cylinder 17 is a positive value (Δ> 0), that is, when the steering cylinder 17 is extended, the steering angles γL of the left and right front wheels 11a and 11b , ΓR becomes a positive value (γL> 0, γR> 0), and the relationship between the steering angle γL of the left front wheel 11a and the steering angle γR of the right front wheel 11b is | γL | γR | As shown in FIG. 4C, when the expansion / contraction amount Δ of the steering cylinder 17 is a negative value (Δ <0), that is, when the steering cylinder 17 contracts, the steering angles γL of the left and right front wheels 11a and 11b , ΓR becomes a negative value (γL <0, γR <0), and the relationship between the steering angle γL of the left front wheel 11a and the steering angle γR of the right front wheel 11b is | γL |> | |

As shown in FIG. 6A, the turning center of the aerial work platform 1 is substantially on the axis of the rear wheels 11c and 11d, and is at infinity (zero steering angle) according to the steering angles of the front wheels 11a and 11b. = When going straight), move to the rear wheels 11c and 11d. Then, when the steering angle becomes maximum, as shown in FIG. 6 (B), if the right turn is performed, the non-driving wheel (rear wheel) 11d on the right side becomes the turning center, and FIG. 6 (C) ), The left non-driving wheel (rear wheel) 11c is configured to be the turning center if the left turning is performed.

Subsequently, in the aerial work platform 1 having the above configuration, the traveling control, the steering control, and the elevating control corresponding to the lever operation and the dial operation in the operating device 40 will be described with reference to FIGS. 2 and 5. Note that FIG. 2 shows a signal and power transmission path related to the traveling operation / steering operation of the traveling body 10 and the raising / lowering operation of the work table 30.

The traveling operation lever 41 provided in the operating device 40 is in a neutral position (position in the vertical posture shown in FIG. 5) in a non-operating state, and can be tilted forward or backward with reference to this neutral position. ing. When the operator's hand is released from the tilted state as described above, the traveling operation lever 41 returns to the neutral position by the restoring force of the built-in spring. The operation state of the travel operation lever 41 (operation direction and operation amount based on the above neutral position) is detected by a travel operation detector 41a composed of a potentiometer or the like provided in the operation device 40, and the detection signal is detected by the travel operation detector 41a. It is input to the controller 50 provided in the traveling body 10 as an operation command signal (operation command information) corresponding to the operation state of the operation lever 41.

The tilting operation from the neutral position of the traveling operation lever 41 to the front corresponds to the forward traveling command of the traveling body 10, and the larger the tilting operation amount from the neutral position, the higher the command speed value at the time of forward traveling in the controller 50. Is set to. The tilting operation from the neutral position to the rear of the traveling operation lever 41 corresponds to the reverse traveling command of the traveling body 10, and the larger the tilting operation amount from the neutral position, the higher the command speed value at the time of reverse traveling in the controller 50. Is set to. At this time, regardless of whether the traveling operation lever 41 is tilted in either the forward or backward direction (that is, whether it is a forward traveling command or a reverse traveling command), the left and right drive wheels are controlled by the controller 50. (Front wheels) 11a and 11b are designed to change gears steplessly. The operation of returning the traveling operation lever 41 to the neutral position corresponds to a stop command (or deceleration command) of the traveling body 10.

The steering dial 42 is in a neutral position (as shown in FIG. 5, a position where the mark M1 displayed on the steering dial 41 and the mark M2 displayed on the operating device 40 coincide with each other) in the non-operating state, and the neutral position is set. As a reference, it is possible to twist the operation clockwise (clockwise) or counterclockwise (counterclockwise). When the operator's hand is released from the twisted state as described above, the steering dial 42 returns to the neutral position by the restoring force of the built-in spring. The operation state of the steering dial 42 (operation direction and operation amount based on the above neutral position) is detected by a steering operation detector 42a composed of a potentiometer or the like provided in the operation device 40, and the detection signal is detected by the steering dial 42. It is input to the controller 50 as an operation command signal (operation command information) corresponding to the operation state of 42.

The clockwise twisting operation of the steering dial 42 corresponds to the steering command to the right of the front wheels 11a and 11b, and the larger the twisting operation amount from the neutral position, the more the target steering angle to the right in the controller 50. Set to a large value. The counterclockwise twisting operation of the steering dial 42 corresponds to the leftward steering command of the front wheels 11a and 11b, and the larger the twisting operation amount from the neutral position, the larger the target steering angle to the left in the controller 50. Set to a large value. The operation of returning the steering dial 42 to the neutral position is a command to return the steering angles of the left and right front wheels 11a and 11b to the zero state (γ _L = γ _R = 0), that is, the traveling body 10 goes straight in the traveling direction. Corresponds to a command to return to the direction.

The elevating operation lever 43 is in a neutral position (position in the vertical posture shown in FIG. 5) in a non-operated state, and can be tilted forward or backward with reference to this neutral position. When the operator's hand is released from the tilting operation state as described above, the elevating operation lever 43 returns to the neutral position by the restoring force of the built-in spring. The operating state of the elevating operation lever 43 (the operation direction and the operation amount based on the above-mentioned neutral position) is detected by the elevating operation detector 43a composed of a potentiometer or the like provided in the operating device 40, and the detection signal is elevated and lowered. It is input to the controller 50 as an operation command signal (operation command information) corresponding to the operation state of the operation lever 43.

The tilting operation forward from the neutral position of the elevating operation lever 43 corresponds to a lowering command for moving the workbench 30 downward, and the larger the tilting operation amount from the neutral position, the lower the target lowering of the workbench 30 in the controller 50. The speed is set to a high value. The tilting operation backward from the neutral position of the lifting / lowering operation lever 43 corresponds to a raising command for moving the workbench 30 upward, and the larger the tilting operation amount from the neutral position, the higher the target raising of the workbench 30 in the controller 50. The speed is set to a high value. The operation of returning the elevating operation lever 43 to the neutral position corresponds to a stop command (or deceleration command) of the workbench 30.

The traveling body 10 is provided with a hydraulic pump P driven by an electric motor M. The hydraulic oil (pressure oil) discharged from the hydraulic pump P is supplied to the steering cylinder 17 via the steering control valve 71. The steering control unit 52 of the controller 50 electromagnetically drives the spool of the steering control valve 71 in a drive direction and a drive amount according to the operation direction and the operation amount of the steering dial 42 to change the valve opening degree from the hydraulic pump P. The supply direction and supply amount of hydraulic oil supplied to the steering cylinder 17 are controlled, and the drive direction and drive speed of the steering cylinder 17 are controlled.

Similarly, the hydraulic oil (pressure oil) discharged from the hydraulic pump P is supplied to the elevating cylinder 21 via the elevating control valve 72. The elevating control unit 51 of the controller 50 electromagnetically drives the spool of the elevating control valve 72 in the driving direction and driving amount according to the operating direction and operating amount of the elevating operation lever 43 to change the valve opening degree, and changes the valve opening degree. Controls the supply direction and supply amount of hydraulic oil supplied to the elevating cylinder 21 and controls the driving direction and driving speed of the elevating cylinder 21.

Here, the drive direction of the spools of the control valves 71 and 72 is related to the drive direction of the corresponding hydraulic cylinders (steering cylinder 17, elevating cylinder 21), and the drive amount of the spools of the control valves 71 and 72 (valve open). Degree) is related to the flow rate (flow rate per unit time) of hydraulic oil supplied to the corresponding hydraulic cylinders (steering cylinder 17, elevating cylinder 21), that is, the driving speed of the hydraulic cylinder. Therefore, when the drive directions of the spools of the control valves 71 and 72 are reversed, the drive directions of the corresponding hydraulic cylinders 17 and 21 are also reversed, and when the drive amount of the spools of the control valves 71 and 72 is increased, the corresponding drive direction is dealt with. The driving speed of the hydraulic cylinders 17 and 21 also increases.

The traveling body 10 includes left and right traveling motors 12a and 12b that independently drive the left and right driving wheels 11a and 11b, and a rotation detector that detects the actual rotation speed (actual rotation speed) of the left and right traveling motors 12a and 12b. 60, 60, a battery B that stores DC power, and an inverter IV that drives each of the traveling motors 12a and 12b by converting the DC power from the battery B into AC power and supplying it to the traveling motors 12a and 12b. Is provided. As the traveling motors 12a and 12b, induction motors driven by AC power converted by the inverter IV are used. The rotation detector 60 is composed of, for example, a rotary encoder or the like. The battery B is a power source for the work vehicle 1, and is configured by connecting a plurality of secondary batteries (for example, lithium ion type or nickel hydrogen type secondary batteries) in series or in parallel with each other. The inverter IV operates based on the command signal from the controller 50, and supplies AC power corresponding to the command signal (command frequency and command voltage value) to the traveling motors 12a and 12b, so that the left and right traveling motors 12a , 12b is driven. Further, the inverter IV reversely converts the AC power output by the regeneration of the left and right traveling motors 12a and 12b and supplies the AC power to the battery B. That is, the battery B is discharged by the power running of the left and right traveling motors 12a and 12b, while being charged by the regeneration of the left and right traveling motors 12a and 12b. In the following description, when the traveling motor 12a on the left side and the traveling motor 12b on the right side are not particularly distinguished, they are simply collectively referred to as "traveling motor 12".

Further, the traveling body 10 includes a steering angle detector 61 that detects the steering angles of the front wheels 11a and 11b from the rotation angles of the left and right front wheels 11a and 11b around the kingpin axis 15, and the traveling body 10 in the front-rear direction with respect to the horizontal plane. The tilt angle detector 62 that detects the tilt angle, the battery voltage detector 63 that detects the voltage of the battery B, the motor temperature detector 64 that detects the winding temperature of the traveling motors 12a and 12b, and the traveling motors 12a and 12b. A motor current detector 65 for detecting the current of the above is provided. Further, in the scissors link mechanism 20, is the elevating speed detector 66 that detects the elevating speed of the workbench 30 from the operating speed of the elevating cylinder 21 and the link mechanism 20 stored on the traveling body 10. A storage detector 67 for detecting whether or not it is provided is provided. Various information detected by these detectors 61 to 67 is input to the controller 50.

As shown in FIG. 2, the controller 50 includes an elevating control unit 51, a steering control unit 52, and a travel control unit 53.

When the lift control unit 51 inputs the operation command information corresponding to the operation state (operation direction and operation amount) of the lift operation lever 43 detected by the lift operation detector 43a, the lift control unit 51 raises and lowers the target according to the operation command information. The speed is calculated, and the spool of the elevating control valve 72 is electromagnetically driven so that the elevating speed of the workbench 30 detected by the elevating speed detector 66 matches the target elevating speed, and the operating speed of the elevating cylinder 21 is controlled.

When the operation command information corresponding to the operation state (operation direction and operation amount) of the steering dial 42 detected by the steering operation detector 42a is input, the steering control unit 52 is the front wheel of the person corresponding to the operation command information. The target steering angles of the (steering wheels) 11a and 11b are set, and steering control is performed so that the steering angles detected by the steering angle detectors 61 provided on the front wheels (steering wheels) 11a and 11b match the target steering angles. The spool of the valve 71 is electromagnetically driven to control the amount of expansion and contraction of the steering cylinder 17.

When the operation command information corresponding to the operation state (operation direction and operation amount) of the travel operation lever 41 detected by the travel operation detector 41a is input, the travel control unit 53 has a rotation speed corresponding to the operation command information. A frequency command and a voltage value command are given to the inverter IV so that the left and right traveling motors 12a and 12b are driven to rotate in common in the rotation direction, and the operation of the inverter IV is controlled. Here, in the present embodiment, so-called 1-inverter-2 motor type control in which two traveling motors 12a and 12b are driven by one inverter IV is realized. Therefore, the left and right traveling motors 12a and 12b are driven under the same frequency and the same applied voltage under the control of one inverter IV. As described above, rotation detectors 60 and 60 are attached to the left and right traveling motors 12a and 12b, respectively, and the actual rotation speeds (actual rotation speeds) of the traveling motors 12a and 12b can be detected, respectively. In the present embodiment, the running control (command frequency) of the high-altitude work vehicle 1 is based on the lower speed of the actual rotation speed of the left traveling motor 12a and the actual rotation speed of the right traveling motor 12b. Control and command voltage value control) are performed. Therefore, in the following, the "actual rotation speed" means the actual rotation speed of the lower speed of the actual rotation speed of the left traveling motor 12a and the actual rotation speed of the right traveling motor 12b. Then, the traveling control unit 53 calculates a rotation speed difference (hereinafter, referred to as “rotation deviation”) between the command rotation speed and the actual rotation speed, and uses this as command frequency control (command rotation speed control) and command voltage. Used as a value control parameter.

The travel control unit 53 simultaneously variably controls the command frequency and the command voltage value according to the V / f control method. The travel control unit 53 includes a frequency control unit 54 that controls a command frequency (command rotation speed) and a voltage control unit 55 that controls a command voltage value, and includes a command frequency calculated by the frequency control unit 54 and a command frequency. The command voltage value calculated by the voltage control unit 55 is output to the inverter IV.

Here, the rotation speed of the traveling motors 12 (12a, 12b) is proportional to the command frequency (frequency of AC power converted by the inverter IV). Further, the output torque of the traveling motor 12 is proportional to the voltage value (or current value) of the AC power supplied to the traveling motor 12. Therefore, in the present embodiment, the rotation speed and output torque of the traveling motor 12 can be arbitrarily adjusted by controlling the command frequency and the command voltage value output to the inverter IV according to the V / f control method. ..

<Command frequency control / Command rotation speed control>
The frequency control unit 54 calculates a command rotation speed (command frequency) according to the operation command information (operation amount of the travel operation lever 41) based on the operation command information from the travel operation detector 41a. Here, the traveling motor (induction motor) 12 has a motor efficiency (0 to 300 rpm) when the rotation deviation between the command rotation speed and the actual rotation speed is within a certain range (0 to 300 rpm) according to the characteristics peculiar to the motor. Operation efficiency) is good. Therefore, when the rotation deviation is within a preset specified value (300 rpm in the present embodiment), the frequency control unit 54 sets the rotation speed according to the operation command information by the traveling operation lever 41 as the command rotation speed. To do. On the other hand, when the rotation deviation exceeds the specified value (300 rpm), the frequency control unit 54 performs a command rotation speed (rotation speed according to the operation command information) so that the rotation deviation converges to the above-mentioned specified value as feedback control. ) Is corrected. That is, when the actual rotation speed exceeds or becomes faster than the command rotation speed by exceeding the specified value, the frequency control unit 54 refers to the rotation speed correction table TN stored in the frequency control unit 54. Then, the command rotation speed is corrected to a rotation speed slower than the rotation speed according to the operation command information.

At this time, the frequency control unit 54 calculates the correction value of the command rotation speed with reference to the rotation speed correction table TN. FIG. 7 is a schematic view showing the rotation speed correction table TN. The rotation speed correction table TN defines the correspondence between the rotation deviation and the correction value. In FIG. 7, the horizontal axis is the rotation deviation, and the vertical axis is the correction value of the command rotation speed. As shown in FIG. 7, when the rotation deviation between the command rotational speed and the actual rotational speed is within a predetermined value ΔN _K (300rpm), the
The correction value of the command rotation speed is zero. On the other hand, when the rotational difference exceeds a predetermined value ΔN _K (300rpm) as the correction value of the command rotational speed, constant correction value H _N (300 rpm) is set. Therefore, the frequency control unit 54, when the rotational difference exceeds a predetermined value ΔN _K (300rpm), the rotational speed obtained by adding the actual rotational speed constant correction value H _N (300 rpm), the command rotational by determining the speed, to keep the rotation deviation between the command rotational speed and the actual rotation speed specified value ΔN _K (300rpm). That is, the corrected command rotation speed is the rotation speed obtained _{by adding the correction value H N} (300 rpm) to the actual rotation speed. However, when the corrected command rotation speed exceeds a preset limit value (for example, 100 rpm), the command rotation speed is maintained at the limit value even when the rotation deviation further increases. The reason is that when the rotation speed exceeds the limit value, the operating point deviates from the outline of the torque diagram related to the current command voltage value to the low torque side, and the output torque may decrease accordingly. Because there is. The frequency control unit 54, the command rotational speed as described above (command frequency) results obtained by correcting the actual rotational speed is increased, in which case the rotational difference has been returned within the specified value .DELTA.N _K (300 rpm) is , The command rotation speed is gradually returned to the rotation speed according to the operation command information.

Here, FIG. 8 is a torque diagram showing the relationship between the rotational speed of the traveling motor 12 and the output torque. In FIG. 8, the horizontal axis is the rotation speed (frequency), and the vertical axis is the output torque. For convenience of explanation, the description of the correction of the command voltage value will be omitted here, but in reality, the command voltage value is corrected at the same time as the command rotation speed (command frequency) is corrected. As shown in FIG. 8, first, _{on the operation line C 1 where the command rotation speed is N 1} (for example, 2500 rpm), the traveling motor 12 is at an appropriate operating point (point a) where the output torque and the load torque match. It is driving. In this operating point (point a), the rotation deviation between the command rotational speed and the actual rotational speed (actual rotational speed at the point a) has remained the within specified value ΔN _K (300rpm). Here, for example, such as by entering the ramp from the flat road, the running when the load torque of the motor 12 is increased, the actual rotation speed of the traveling motor 12 is reduced, operation line C ₁ operating point the point on a Moves from to the low speed side (high torque side). At this time, in the conventional rotation speed control, the operating line and operating point of the traveling motor 12 are moved to the operating line and operating point where the maximum torque can be output so that the aerial work platform 1 does not escape or stop on the ramp. As a result, the running speed dropped sharply and wasted power was consumed. In contrast, in the present embodiment, when the rotational difference between the commanded rotational speed and the actual rotation speed exceeds a specified value ΔN _K (300rpm), adapted to correct the command rotational speed. That is, when the rotational difference exceeds a predetermined value ΔN _K (300rpm), by correcting the command rotational speed obtained by adding a constant correction value H _N (300 rpm) the actual rotational speed, finger Ordinance rotation gradually slow down (we are slower than the rotational speed corresponding to the operation command), the rotational deviation is adapted to perform a feedback control to converge to predetermined value .DELTA.N _K (300 rpm). As a result, although not shown, the operation line is sequentially switched according to the corrected command rotation speed, and the operation point is moved to an operating point where a higher output torque can be obtained on the operation line. Therefore, fine travel control that maximizes the motor characteristics of the travel motor 12 can be realized. Then, the command rotation speed is switched to the operation line C _{2 where the command rotation speed is N 2,} and the output torque of the traveling motor 12 moves to an appropriate operation point (point b) that matches the load torque, whereby the command rotation speed and the actual rotation speed are reached. rotation deviation (actual rotational speed at the point b) is to be restored to a specified value .DELTA.N _K. By performing such rotation speed correction, it is possible to drive the aerial work platform 1 on the ramp without consuming unnecessary electric power and without suddenly reducing the traveling speed.

<Command voltage value control>
The voltage control unit 55 calculates a command voltage value according to the command frequency (command rotation speed) determined above with reference to a preset V / f pattern. Here, the voltage control unit 55 stores a plurality of types of V / f patterns (V / f pattern table) that define the relationship between the command frequency (command rotation speed) and the command voltage value. The voltage control unit 55 selects any V / f pattern from a plurality of types of V / f patterns according to the V / f characteristic ratio calculated by the voltage control process described later. Then, the voltage control unit 55 refers to the selected V / f pattern and determines the voltage value calculated according to the command frequency as the command voltage value.

Here, the voltage control unit 55 is set with a voltage value usage range (maximum voltage value V _max , minimum voltage value V _min ) with respect to the command frequency (command rotation speed). The maximum voltage value V _max is a steady-state voltage value determined by the design value of the motor, and the minimum voltage value V _min is the minimum voltage value required to travel at the command rotation speed. The range of use of this voltage value (maximum voltage value V _max , minimum voltage value V _min ) can differ depending on the command frequency (command rotation speed).

FIG. 9 is a schematic diagram showing an example of the V / f pattern. The V / f pattern is a function indicating the relationship between the command frequency and the command voltage value, and is stored in a numerical value, a table, or a map in a format suitable for reading or referencing. In the V / f pattern, V / f (voltage / frequency) becomes constant until the predetermined frequency is reached, and V (voltage) becomes constant when the frequency exceeds the predetermined frequency. In the present embodiment, the minimum voltage value V _min is defined as "0%" as the V / f characteristic ratio, and the maximum voltage value V _max is defined as "100%" as the V / f characteristic ratio, and the usage range (V) of the above voltage value is defined. _The V / f characteristic ratio corresponding to each voltage value is set within min ~ V _max).

In this embodiment, a plurality of types of V / f patterns are prepared according to the V / f characteristic ratio. Specifically, a V / f pattern of 0% to 100% is prepared as the V / f characteristic ratio, and V / f is performed in the voltage control process (first voltage control process, second voltage control process) described later. When the characteristic ratio is calculated, the V / f pattern corresponding to the V / f characteristic ratio is selected. That is, the V / f characteristic ratio and the V / f pattern are stored in a one-to-one correspondence relationship, and the V calculated by the voltage control processing (first voltage control processing, second voltage control processing) described later. The V / f pattern is uniquely determined according to the / f characteristic ratio. Then, in the voltage control process described later, the command voltage value is set or corrected with the V / f characteristic ratio as a parameter. In the above-mentioned plurality of types of V / f patterns, the command voltage value corresponding to the same command frequency is set to increase as the V / f pattern having a larger V / f characteristic ratio is selected. .. Therefore, under the same command frequency, the command voltage value can be increased as the V / f characteristic ratio is increased, and the command voltage value can be decreased as the V / f characteristic ratio is decreased. Therefore, increasing or decreasing the V / f characteristic ratio is synonymous with increasing or decreasing the command voltage value (output voltage value).

The voltage control unit 55 performs the first voltage control process and the second voltage control process in parallel at the same time, and determines the optimum command voltage value suitable for the current traveling state. The voltage control unit 55 includes a plurality of types of voltage control tables TV ₁ to calculate the V / f characteristic ratio in the above voltage control process.
TV ₅ is stored. _{The voltage control unit 55 refers to these voltage control tables TV 1 to} TV ₅ based on the detection information from various detectors provided on the aerial work platform 1, and V is used for each voltage control process. Calculate the / f characteristic ratio. Then, the voltage control unit 55 compares the V / f characteristic ratio calculated by the first voltage control process with the V / f characteristic ratio calculated by the second voltage control process, and as a result, the larger V / f Select the characteristic ratio as the optimum value.

≪First voltage control process≫
The first voltage control process is mainly a voltage control process suitable for normal running. As the first voltage control process, the voltage control unit 55 parameters (variables) the tilt angle of the traveling body 10 detected by the tilt angle detector 62 and the rotation deviation between the command rotation speed and the actual rotation speed. , The V / f characteristic ratio is calculated.

First, the voltage control unit 55 calculates a correction value of the V / f characteristic ratio (hereinafter referred to as “correction value A”) with reference to the _{voltage control table TV 1.} FIG. 10 is a schematic view showing the voltage control table TV _1. The voltage control table TV ₁ defines the correspondence between the tilt angle and the correction value A. In FIG. 10, the horizontal axis is the inclination angle, and the vertical axis is the correction value A of the V / f characteristic ratio. This correction value A is calculated according to the inclination angle of the traveling body 10 detected by the inclination angle detector 62. Specifically, as shown in FIG. 10, when the tilt angle is θ _A or less, the tilt angle and the correction value A have a proportional relationship, and a correction value A having a magnitude proportional to the tilt angle is set. .. Whenever the tilt angle _{exceeds θ A , HA} (for example, 100%) is set as the correction value A. The inclination angle θ _A can be set as appropriate, but for example, θ _A is “10 degrees”.

Subsequently, the voltage control unit 55 calculates a correction value of the V / f characteristic ratio (hereinafter referred to as “correction value B”) with reference to the _{voltage control table TV 2.} FIG. 11 is a schematic view showing the voltage control table TV _2. The voltage control table TV ₂ defines the correspondence between the rotation deviation and the correction value B. In FIG. 11, the horizontal axis is the rotation deviation, and the vertical axis is the correction value B of the V / f characteristic ratio. At this time, as described above, the traveling motor (induction motor) 12 has a rotation deviation between the commanded rotation speed and the actual rotation speed within a certain range (0 to 300 rpm in the present embodiment) according to the characteristics peculiar to the motor. At some point, the motor efficiency is good, especially when the rotational deviation matches the optimum value (200 rpm in this embodiment). Therefore, the voltage control unit 55 calculates the correction value B of the V / f characteristic ratio based on the difference between the rotation deviation and the optimum value (200 rpm). Specifically, as shown in FIG. 11, the correction value B of the rotational deviation and V / f characteristic ratio is proportional, the rotational deviation and the optimum value ΔN difference in magnitude proportional to the _A correction value B (H _{B1 to} H _B2 ) is set. As an example of the correction value B, H _B1 is "-50%" and H _B2 is "
50% ". In this case, if the rotational difference matches the optimal value .DELTA.N _A, the correction value B is zero. On the other hand, when the rotation deviation is smaller than the optimum value .DELTA.N _A (motor load is small), the (correction value acting in a direction to lower the voltage) negative correction value B corresponding to the difference is set. Conversely, when the rotation deviation is greater than the optimum value .DELTA.N _A (motor load is large), (correction value acting in a direction to raise the voltage) positive correction value B corresponding to the difference is set. Incidentally, when the rotation deviation exceeds a predetermined value .DELTA.N _B (e.g. 500 rpm), always correction value B is H _B2.

Then, the voltage control unit 55 adds the correction value A and the correction value B of the V / f characteristic ratio as the result value of the first voltage control processing, and the cumulative value of the V / f characteristic ratio (hereinafter, “V /”). f characteristic ratio α ”) is calculated. For example, when the correction value A of the V / f characteristic ratio is "30%" and the correction value B of the V / f characteristic ratio is "10%", the cumulative value (V / f characteristic ratio α) is "40". % ”. However, in the present embodiment, the upper limit value of the V / f characteristic ratio α is set to “100%”, and when the V / f characteristic ratio α exceeds the upper limit value (100%), the upper limit value is exceeded. Truncate the minutes.

Here, in the first voltage control process, when the rotation deviation exceeds the optimum value (200 rpm), the voltage is corrected and the output torque of the traveling motor 12 is adjusted. On the other hand, in the frequency control process (rotational speed control process) described above, when the rotational deviation exceeds a specified value (300 rpm), frequency correction (rotational speed correction) is performed to adjust the output torque of the traveling motor 12. That is, in order to adjust the output torque of the traveling motor 12, voltage correction is performed when the rotational deviation exceeds the optimum value (200 rpm), but frequency correction is not performed at that time, and the frequency correction has a rotational deviation. It is performed when the specified value (300 rpm) is exceeded. That is, in the present embodiment, the adjustment of the output torque by the voltage correction is prioritized over the adjustment of the output torque by the frequency correction. The reason is that if the command frequency is corrected, the traveling speed of the work vehicle 1 (rotational speed of the traveling motor 12) also changes accordingly. Therefore, first, the command voltage value is prioritized without changing the command frequency. This is because the work vehicle 1 can be driven without giving any discomfort to the worker who boarded the work vehicle 1 by making the correction.

≪Second voltage control process≫
The second voltage control process is mainly a voltage control process suitable for traveling on a step. Here, it is necessary to secure a high output torque on the ascending step, and it is necessary to brake the acceleration of the vehicle and secure a sufficient regenerative torque on the descending step. However, the existence of a step on the road surface may not be determined by the inclination angle of the traveling body 10 (in particular, even if there is a step on the road surface, the inclination angle of the traveling body when the road surface itself is flat ground). (Because it becomes very small), there is a possibility that a sufficient output voltage (output torque) cannot be secured when traveling on a step by the above-mentioned first voltage control process. At this time, if the ascending step cannot be advanced, the actual rotation speed cannot follow the command rotation speed, and the actual rotation speed tends to be small and the rotation deviation tends to be large. Further, when traveling down a step (when starting to run), the command rotation speed tends to be small and the actual rotation speed tends to be small due to a low-speed operation or an inching operation. Therefore, the voltage control unit 55 uses these characteristics to calculate the V / f characteristic ratio with the actual rotation speed, the command rotation speed, and the rotation deviation as parameters (variables) as the second voltage control process.

The voltage control unit 55 calculates a correction value of the V / f characteristic ratio (hereinafter referred to as “correction value C”) with reference to the _{voltage control table TV 3} when the actual rotation speed of the traveling motor 12 is in the low speed range. To do. FIG. 12 is a schematic view showing the voltage control table TV _3. The voltage control table TV ₃ defines the correspondence between the actual rotation speed and the correction value C. In FIG. 12, the horizontal axis is the actual rotation speed, and the vertical axis is the correction value C of the V / f characteristic ratio. This correction value C is calculated according to the actual rotation speed detected by the rotation detector 60. Specifically, as shown in FIG. 12, until the actual rotational speed reaches the N _A (e.g. 250 rpm), always, H _C (e.g. 50%) is set as the correction value C. Moreover, the actual rotation speed when the above N _A and equal to or less than N _B, the correction value C which is proportional to the magnitude of the actual rotation speed is set. Then, the actual rotational speed N _B (e.g. 500rp
When it exceeds m), the correction value C always becomes zero.

When the command rotation speed of the traveling motor 12 is in the low speed range (when the operating amount of the traveling operation lever 41 is very small), the voltage control unit 55 refers to the voltage control table TV ₄ and refers to the V / f characteristic ratio. (Hereinafter referred to as "correction value D") is calculated. FIG. 13 is a schematic view showing the voltage control table TV _4. The voltage control table TV ₄ defines the correspondence between the command rotation speed and the correction value D. In FIG. 13, the horizontal axis is the command rotation speed, and the vertical axis is the correction value D of the V / f characteristic ratio. This correction value D is calculated according to the command rotation speed set according to the operation state (operation amount) of the traveling operation lever 41. Specifically, as shown in FIG. 13, the command rotational speed until it reaches the N _A (e.g. 250 rpm), always, H _D (e.g. 50%) is set as the correction value D. Further, if the command rotational speed is equal to or less than N _A and not more than N _B, the correction value D which is proportional to the magnitude of the command rotational speed is set. Then, the command rotational speed is more than N _B (e.g. 500 rpm), always correction value D is zero.

When a rotation deviation occurs between the command rotation speed and the actual rotation speed, the voltage control unit 55 refers to the voltage control table TV ₅ and corrects the V / f characteristic ratio (hereinafter, “correction value E”). ") Is calculated. FIG. 14 is a schematic view showing the voltage control table TV _5. The voltage control table TV ₅ defines the correspondence between the rotation deviation and the correction value E. In FIG. 14, the horizontal axis is the rotation deviation, and the vertical axis is the correction value E of the V / f characteristic ratio. The correction value E of the V / f characteristic ratio is the rotation between the command rotation speed set according to the operation state (operation amount) of the traveling operation lever 41 and the actual rotation speed detected by the rotation detector 60. Calculated according to the deviation. Specifically, as shown in FIG. 14, until the rotational deviation reaches a predetermined value .DELTA.N _C, rotation deviation and the correction value E
Is in a proportional relationship with, and a correction value E having a magnitude proportional to the rotation deviation is set. On the other hand, when the rotation deviation is equal to or greater than a predetermined value .DELTA.N _C, always, the correction value E becomes H _E (for example, 100%). In the present embodiment, the predetermined value ΔNc is set to the same value (3500 rpm) as the rated rotation speed (3500 rpm) of the traveling motor 12. Therefore, the voltage control table TV ₅ is designed assuming that the command rotation speed is the rated rotation speed and the actual rotation speed is zero (rotational deviation = 3500 rpm). In this second voltage control process, the running performance is prioritized over the operating efficiency of the traveling motor 12, so that even when the rotation deviation matches the above optimum value (200 rpm), the V / f characteristic ratio A certain value is added as the correction value E.

The voltage control unit 55 adds up the correction value C to the correction value E of the V / f characteristic ratio as the result value of the second voltage control processing, and the cumulative value of the V / f characteristic ratio (hereinafter, “V / f characteristic ratio”). Beta ”) is calculated. For example, when the correction value C of the V / f characteristic ratio is "10%", the correction value D of the V / f characteristic ratio is "40%", and the correction value E of the V / f characteristic ratio is "30%". As a cumulative value thereof, the V / f characteristic ratio β is “80%”. However, in the present embodiment, the upper limit value of the V / f characteristic ratio β is set to “100%”, and when the V / f characteristic ratio β exceeds the upper limit value (100%), the upper limit value is exceeded. Truncate the minutes.

The voltage control unit 55 compares the V / f characteristic ratio α calculated in the first voltage control process with the V / f characteristic ratio β calculated in the second voltage control process, and compares the V / f characteristic ratio β calculated in the second voltage control process with the larger V / f characteristic ratio β. The f characteristic ratio is determined as an appropriate value, and a V / f pattern corresponding to this appropriate value (V / f characteristic ratio = 0 to 100%) is selected. Then, the voltage control unit 55 refers to the selected V / f pattern and determines the voltage value corresponding to the command frequency calculated by the frequency control unit 54 as the command voltage value. Specifically, the command voltage value is based on the above-calculated V / f characteristic ratio and the minimum voltage value V _min and the maximum voltage value V _{max set according to the command frequency (command rotation speed).} Calculated according to (1).
Command voltage value = (V _max −V _min ) × V / f characteristic ratio + V _min ... (1)

The travel control unit 53 outputs the command frequency information (command rotation speed information) determined by the frequency control unit 54 and the command voltage value information determined by the voltage control unit 55 to the inverter IV. Then, the inverter IV is switched and controlled based on the command information (command frequency information, command voltage value information) from the travel control unit 53 to generate AC power according to the command frequency and command voltage value. This is supplied to the left and right traveling motors 12a and 12b.

As described above, in the present embodiment, one of the V / f characteristic ratios α and β is determined as an appropriate value of the V / f characteristic ratio according to the traveling state of the aerial work platform 1. The set values of the above voltage control tables TV _{1 to} TV ₅ are basically such that the V / f characteristic ratio α is larger than the V / f characteristic ratio β during normal driving, etc., and when traveling on a step. The V / f characteristic ratio β is set to be larger than the V / f characteristic ratio α at the start of a running operation or the like.

For example, when the aerial work platform 1 is steadily traveling at a certain traveling speed (medium speed range, high speed range), basically, correction values C and D for voltage correction in the low speed range. Are both zero or minute values. In addition, if the rotation deviation is small (if the vehicle can run almost according to the operation command), the correction value E is also small, so that the V / f characteristic ratio α is V / f. It becomes larger than the characteristic ratio β. In that case, the motor efficiency is always optimal by adding the correction value B calculated according to the difference between the rotation deviation and the optimum value to the correction value A set according to the inclination angle of the traveling body 10. The traveling motor 12 can be driven at the operating point.

Further, when the high-altitude work vehicle 1 enters an ascending step, if the step cannot be overcome even if the command rotation speed is increased, the actual rotation speed cannot follow the command rotation speed and the rotation thereof. As the deviation increases, the correction values C and E become larger, so that the V / f characteristic ratio β becomes larger than the V / f characteristic ratio α. At this time, regarding the V / f characteristic ratio α, the correction value A does not change unless the inclination angle of the traveling body 10 changes on a flat ground, and the rotation deviation exceeds a predetermined value (ΔN ₂ = 500 rpm). And the correction value B is always constant, so
It is unlikely that the output torque of the traveling motor 12 will increase any further. On the other hand, regarding the V / f characteristic ratio β, as the operator increases the operation amount of the traveling operation lever 41, the actual rotation speed cannot follow the command rotation speed and the rotation deviation increases. Therefore, the rotation deviation increases. The correction value E gradually increases until the value reaches the upper limit value (rotational deviation corresponding to the rated rotation speed). Therefore, as described above, the V / f characteristic ratio β is larger than the V / f characteristic ratio α, and voltage correction corresponding to the operator's operation intention becomes possible. As a result, the output torque of the traveling motor 12 also increases according to the amount of operation of the operating lever 41, and finally, it becomes possible to overcome the above-mentioned ascending step.

Further, when the aerial work platform 1 enters the down step, when the running operation is started or the inching operation is performed, the command rotation speed and the actual rotation speed are in the low speed range, so that the correction value C, D becomes large, and the V / f characteristic ratio β becomes larger than the V / f characteristic ratio α. At this time, regarding the V / f characteristic ratio α, the correction value A does not change unless the inclination angle of the traveling body 10 changes on a flat ground, and in this operation start state, the motor load is light and the rotation deviation is small. If the correction value B is also reduced, the output torque of the traveling motor 12 is unlikely to increase further. On the other hand, with respect to the V / f characteristic ratio β, since the command rotation speed and the actual rotation speed are in the low speed range, the correction values C and D are always maintained at the upper limit values (for example, 50%). Therefore, as described above, since the V / f characteristic ratio β is larger than the V / f characteristic ratio α, the output torque of the traveling motor 12 is increased more than in the normal state, and the aerial work platform 1 is used in the down step. It is possible to effectively brake the traveling motor 12 from accelerating due to its own weight.

Further, when the aerial work platform 1 starts to move on an uphill slope, for example, if the slope is steep at 10 degrees or more, the correction value A of the V / f characteristic ratio becomes the maximum value (for example, 100%), so that V / The f characteristic ratio α is larger than the V / f characteristic ratio β. On the other hand, if the road surface has a gentle slope, the command rotation speed and the actual rotation speed are in the low speed range when the aerial work platform 1 starts to move, and the correction values C and D are both upper limit values (for example, 50%). The V / f characteristic ratio β is larger than the V / f characteristic ratio α. In this way, when the aerial work platform 1 starts to move, the output torque of the traveling motor 12 can always be increased regardless of the inclination angle of the road surface, so that the aerial work platform 1 escapes on the inclined surface. The situation can be prevented (the situation where the traveling motor 12 reverses with respect to the operation command direction can be prevented).

Next, the procedure of the traveling control process of the aerial work platform 1 in the present embodiment will be described. FIG. 15 is a flowchart showing the procedure of the traveling control process of the aerial work platform 1 in the present embodiment.

First, in the aerial work platform 1, when the traveling operation lever 41 is tilted by the operator on the workbench 30, the operation command information is input to the traveling control unit 53 of the controller 50 (step S1). The frequency control unit 54 of the controller 50 calculates the command rotation speed (command frequency) according to the input operation amount (step S2).

Here, while the aerial work platform 1 is traveling, the actual rotation speed (actual rotation speed) of the traveling motor 12 is detected by the rotation detector 60, and this actual rotation speed information is input to the traveling control unit 53. (Step S3). The travel control unit 53 calculates the difference between the command rotation speed calculated in step S1 and the actual rotation speed input in step S3 as a rotation deviation (step S4).

Subsequently, the frequency control unit 54 refers to the rotation speed control table TN, compares the rotation deviation calculated in step S4 with the preset specified value (300 rpm), and determines the rotation deviation. If the value is exceeded, a constant correction value H _{N is used as the correction value for the command rotation speed.}
Is set (step S5). Then, when the rotation deviation exceeds the specified value, the frequency control unit 54 adds the correction value set in S5 to the actual rotation speed input in step S3 to obtain the rotation speed. , The final command rotation speed instructed to the inverter IV is determined (step S6). If the rotation deviation does not exceed the specified value, the command rotation speed calculated in step S2 is maintained as it is (step S6).

Further, the travel control unit 53 inputs the inclination angle of the traveling body 10 detected by the inclination angle detector 62 (step S7). The voltage control unit 55 calculates the correction value A of the V / f characteristic ratio based on the inclination angle of the traveling body 10 input in step S7 with reference to the _{voltage control table TV 1 (step S8).} Next, the voltage control unit 55 refers to the voltage control table TV ₂ , compares the rotation deviation calculated in step S4 with the preset optimum value (200 rpm), and V according to the difference. The correction value B of the / f characteristic ratio is calculated (step S9). Then, the voltage control unit 55 adds the correction value B of the V / f characteristic ratio calculated in step S9 to the correction value A of the V / f characteristic ratio calculated in step S8 (step S10). As a result of the above addition, the voltage control unit 55 calculates the cumulative value as the V / f characteristic ratio α (step S11).

Further, the voltage control unit 55 calculates the correction value C of the V / f characteristic ratio based on the actual rotation speed input in step S3 with reference to the _{voltage control table TV 3 (step S12).} Further, the voltage control unit 55 calculates the correction value D of the V / f characteristic ratio based on the command rotation speed calculated in step S2 with reference to the _{voltage control table TV 4 (step S13).} Further, the voltage control unit 55 refers to the voltage control table TV ₅ and refers to the above step S4.
The correction value E of the V / f characteristic ratio is calculated based on the rotation deviation calculated in (step S14). Then, the voltage control unit 55 adds the correction values C, D, and E of the V / f characteristic ratio calculated in steps S12 to S14 (step S15). As a result of the above addition, the voltage control unit 55 calculates the cumulative value as the V / f characteristic ratio β (step S16).

Subsequently, the voltage control unit 55 has the V / f characteristic ratio α calculated in the first voltage control process (steps S8 to S11) and the V calculated in the second voltage control process (steps S12 to S16). The / f characteristic ratio β is compared (step S17). Then, as a result of the comparison in step S17, the voltage control unit 55 determines the larger V / f characteristic ratio among the V / f characteristic ratios α and β as an appropriate value (step S18).

Next, the voltage control unit 55 selects a V / f pattern according to the V / f characteristic ratio (0 to 100%) determined in step S18, and refers to the selected V / f pattern as described above. The command voltage value according to the command frequency (command rotation speed) determined in step S6 is determined (step S19).

The travel control unit 53 outputs the command frequency (f) determined in step S6 and the command voltage value (V) determined in step S19 to the inverter IV (step S20). After that, by repeatedly executing the operation processes of steps S1 to S20 at predetermined cycles, the traveling control process of the aerial work platform 1 is appropriately performed, and there is no sense of discomfort that matches the operation intention of the operator. , Safe and excellent running performance is realized.

As described above, according to the present embodiment, the rotation deviation between the command rotation speed set by the operation of the traveling operation lever 41 and the actual rotation speed detected by the rotation detector 60 is calculated, and the rotation deviation is set in advance. By correcting the voltage value of the AC power supplied to the traveling motor 12 according to the difference from the optimum value, the traveling motor 12 can always be driven at an efficient operating point. It is possible to reduce the power consumption of the battery B by suppressing the heat generation of the traveling motor 12 and the inverter IV while maintaining the traveling performance of the above.

Further, according to the present embodiment, when the rotation deviation between the command rotation speed and the actual rotation speed exceeds a preset predetermined value, the maximum torque is output at the command rotation speed of the traveling motor as in the conventional case. Work in high places while maximizing the characteristics of the traveling motor 12 in order to perform feedback control that corrects the commanded rotation speed so that the rotation deviation is maintained at the specified value without reducing the rotation speed to a possible speed. It is possible to improve the running performance of the vehicle 1.

Further, according to the present embodiment, by selectively executing the first voltage control process and the second voltage control process in which the parameters of the voltage control are different from each other, the voltage corresponding to the traveling state of the aerial work platform 1 is obtained. As control, it is possible to establish voltage control suitable for the road surface condition.

In addition, according to the present embodiment, the V / f characteristic ratio α calculated in the first voltage control process is compared with the V / f characteristic ratio β calculated in the second voltage control process. By determining the voltage value of the AC power supplied to the traveling motor 12 based on the larger V / f characteristic ratio, the optimum output voltage according to the traveling state of the high-altitude work vehicle 1 is supplied to the traveling motor 12. It becomes possible to do.

Further, according to the present embodiment, the aerial work platform 1 cannot advance due to the step on the road surface, and the actual rotation speed follows the command rotation speed even though the operator is increasing the amount of operation. If it does not go (when the actual rotation speed is small and the rotation deviation is large), the voltage correction that reflects the operation intention of this operator is performed (the command voltage value is increased according to the above operation amount). Therefore, the aerial work platform 1 can properly overcome the step under the high output torque, and the running performance of the aerial work platform 1 can be further improved.

The present invention is not limited to the above embodiment, and can be appropriately improved as long as it does not deviate from the gist of the present invention.

In the above embodiment, the front wheel provided on the traveling body is configured as a driving wheel, but the present invention is not limited to this configuration, and the rear wheel may be configured as a driving wheel. Similarly, in the above embodiment, the front wheel is configured as a steering wheel, but the present invention is not limited to this configuration, and the rear wheel may be configured as a steering wheel. The drive wheels and the steering wheels do not necessarily have to match. For example, the front wheels may be the drive wheels and the rear wheels may be the steering wheels, and the front wheels may be the steering wheels and the rear wheels. The wheels on the side may be drive wheels.

In the above embodiment, the rotation detectors are provided for each of the left and right traveling motors, but the present invention is not limited to this configuration, and the rotation detectors are provided for only one of the left and right traveling motors. May be good.

In the above embodiment, the control is performed by a 1-inverter-2 motor type in which two traveling motors are driven by one inverter, but the present invention is not limited to this configuration, and two traveling motors are used. Two-inverter-motor type control driven by the inverter of the above may be adopted.

In the above embodiment, the V / f characteristic ratio α calculated by the first voltage control process and the V / f characteristic ratio β calculated by the second voltage control process are compared, and the larger V / f characteristic is obtained. The command voltage value was calculated by referring to the V / f pattern corresponding to the ratio, but the present invention is not limited to this configuration, and is calculated by referring to the V / f pattern corresponding to the V / f characteristic ratio α, for example. The command voltage value α is compared with the command voltage value β calculated by referring to the V / f pattern corresponding to the V / f characteristic ratio β, and the larger command voltage value is adopted. May be good.

In the above embodiment, the valve opening degree of each control valve is changed to control the supply amount of hydraulic oil in the operation control of the hydraulic drive device, but the present invention is not limited to this configuration, and the valve of each control valve is not limited to this. The opening degree may be constant and the number of revolutions of the hydraulic pump may be changed to control the supply amount of hydraulic oil.

In the above embodiment, as the elevating device provided on the traveling body of the aerial work platform, a scissor link type elevating device for vertically elevating and lowering the work table has been described as an example, but the present invention is not limited to this configuration. For example, a mast-type lifting device that vertically raises and lowers the workbench, a boom-type lifting device that moves the workbench three-dimensionally, and the like may be used.

1 Aerial work platform (work vehicle)
10 Traveling body 11 Wheels 12 Traveling motor (induction motor)
20 Scissor link mechanism 30 Worktable 40 Operation device 41 Travel operation lever (operation means)
50 Controller 51 Elevation control unit 52 Steering control unit 53 Travel control unit (travel control means)
54 Frequency control unit 55 Voltage control unit 60 Rotation detector (rotation detection means)
62 Tilt angle detector (tilt angle detecting means)
B Battery IV Inverter

Claims (4)

A traveling body that is provided with a pair of left and right wheels on the front and rear of the vehicle body, and the pair of left and right wheels on either the front side or the rear side are driving wheels.
An induction motor that drives the drive wheels and
A rotation detecting means for detecting the actual rotation speed of the induction motor, and
A battery for supplying electric power to the induction motor and
An operation means for setting a running command value according to an operation by an operator, and
An inverter that converts DC power from the battery into AC power and supplies it to the induction motor to drive the drive wheels.
It is provided with a traveling control means for controlling the operation of the inverter so that AC power having a command frequency corresponding to a command rotation speed set based on the traveling command value is supplied to the induction motor.
The traveling control means corrects the voltage value of the AC power supplied to the induction motor based on the difference between the rotation speed difference between the command rotation speed and the actual rotation speed and the preset reference value. Then, when the rotation speed difference exceeds a preset specified value, the travel control device for a work vehicle is characterized in that the command rotation speed is corrected so as to maintain the rotation speed difference at the specified value. .. A tilt angle detecting means for detecting a tilt angle of the traveling body in the front-rear direction with respect to a horizontal plane is provided.
A first voltage control process that controls the voltage value of AC power supplied to the induction motor based on the rotation speed difference and the tilt angle.
It has a second voltage control process that controls the voltage value of AC power supplied to the induction motor based on the rotation speed difference and at least one of the command rotation speed and the actual rotation speed.
The travel control device for a work vehicle according to claim 1 , wherein the travel control means selectively executes the first voltage control process and the second voltage control process. The larger of the voltage value calculated by the first voltage control process and the voltage value calculated by the second voltage control process is used as the voltage value of the AC power supplied to the induction motor. The travel control device for a work vehicle according to claim 2 , wherein the determination is made. In the second voltage control process, when the actual rotation speed is smaller than a preset predetermined rotation speed and a rotation speed difference occurs between the commanded rotation speed and the actual rotation speed, the rotation is performed. The travel control device for a work vehicle according to claim 3 , wherein the voltage value of the AC power supplied to the induction motor is increased according to the magnitude of the speed difference.

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