JP2019013116A - Electrically-driven travel control device and electrically-driven fork lift - Google Patents

Abstract

To acquire necessary brake power, when a brake pedal stepping-down amount and vehicle speed satisfy prescribed conditions.SOLUTION: An electrically-driven travel control device used for an electric vehicle including an accelerator pedal, a brake pedal, and an electromagnetic parking brake device for imparting electromagnetic brake force to a wheel based on a parking brake command, includes a control part for driving and controlling an electric motor for travel based on an accelerator pedal stepping-down amount and/or a brake pedal stepping-down amount. The control part operates the electromagnetic parking brake device, when such conditions are satisfied that the brake pedal stepping-down amount is a prescribed value or larger, and that vehicle speed is a prescribed value or higher.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an electric travel control device and an electric forklift.

  In an electric vehicle, for example, an electric forklift, the driving electric motor is driven and controlled based on the amount of depression of an accelerator pedal and a brake pedal. When the accelerator pedal is released, regenerative braking force is obtained by regenerative control. When the accelerator pedal is released and the brake pedal is depressed, a regenerative braking force corresponding to the amount of depression of the brake pedal is obtained (for example, Patent Document 1).

JP 2002-101501 A

  However, under a predetermined traveling condition, the necessary braking force may not be exhibited only with the regenerative brake.

According to the first aspect, an electric travel control device used in an electric vehicle including an accelerator pedal, a brake pedal, and an electromagnetic parking brake device that applies an electromagnetic braking force to a wheel based on a parking brake command is provided on the accelerator pedal. A control unit that controls driving of the electric motor for travel based on the depression amount and / or the depression amount of the brake pedal, wherein the control unit has a depression amount of the brake pedal equal to or greater than a predetermined value and a vehicle speed is predetermined; When the condition equal to or greater than the value is satisfied, the electromagnetic parking brake device is operated.
The electric forklift according to the second aspect includes an accelerator pedal, a brake pedal, an accelerator sensor that detects a depression amount of the accelerator pedal, a brake sensor that detects a depression amount of the brake pedal, and a vehicle speed sensor that detects a vehicle speed. The electromagnetic parking brake device, the electric motor for traveling, and the electric traveling control device of the first aspect are provided.

  According to the present invention, it is possible to obtain a necessary braking force under a predetermined condition of the brake pedal depression amount and the vehicle speed.

It is a side view of the electric forklift according to the embodiment. It is a lineblock diagram of an electric system applied to an electric forklift of an embodiment. It is a figure which shows notionally the flow of the signal transmitted / received between the elements which comprise a braking device. It is a figure which shows the relationship between the depression amount when a brake pedal is depressed, a depression force, and deceleration. It is a flowchart explaining the processing procedure of the braking control of VCM103.

In the following description, an electric forklift is taken as an example of a traveling vehicle according to an embodiment of the present invention.
FIG. 1 is a side view of an electric forklift according to an embodiment. The electric forklift 1 includes a vehicle body 4 provided with traveling wheels 2 and a driver's seat 3, and a cargo handling device 5 provided at the front of the vehicle body 4. The cargo handling device 5 is arranged in a pair of left and right outer masts 6 fixed to the front portion of the vehicle body 4, a pair of left and right inner masts 7 supported and guided by the outer mast 6, and movable up and down on the inner mast 7. And a pair of left and right forks 9 provided on the front side of the carriage 8 for holding a load.

  A chain 10 is provided between the carriage 8 and the outer mast 6, and an intermediate portion of the chain 10 is wound around a sheave 11 that is a guide ring provided on the upper portion of the inner mast 7 to suspend the carriage 8. doing. The inner mast 7 is moved up and down by a lift cylinder 12 fixedly supported by the outer mast 6. Therefore, when the inner mast 7 is raised and lowered by the lift cylinder 12, the carriage 8 and the fork 9 provided on the carriage 8 are raised and lowered via the chain 10 by raising and lowering the sheave 11. The lift cylinder 12 is arranged on the left and right of the outer mast 6 and the chain 10 is also arranged on the left and right. Further, a tilt cylinder 13 is provided between the outer mast 6 and the vehicle body 4 to tilt the outer mast 6 in the front-rear direction.

FIG. 2 is a configuration diagram of an electric system 100 in an embodiment in which the present invention is applied to the electric forklift 1. FIG. 3 is a diagram conceptually showing the flow of signals exchanged between elements constituting the braking device.
As shown in FIG. 2, the electric forklift 1 travels by applying driving force to left and right front wheels by electric motors 104L and 104R for traveling (hereinafter referred to as traveling motors). The electric system 100 includes an accelerator sensor 101 that detects the amount of depression of the accelerator pedal 101A, a brake sensor 102 that detects the amount of depression of the brake pedal 102A, and an accelerator depression amount signal SAD input from the accelerator sensor 101 to A vehicle control module (hereinafter referred to as VCM) 103 which is a control unit to be controlled, traveling motors 104R and 104L which are provided independently on the left and right front wheels and apply driving force to the left and right wheels, and a motor drive signal SML output from the VCM 103 , Inverters 105R and 105L that are driven and controlled by SMR to independently control the traveling motors 104R and 104L, and traveling motors 104L and 104R, that is, electromagnetic brakes 106R and 106L that apply braking force to the wheels to brake the electric forklift 1. To have. The brake depression amount signal SBD output from the brake sensor 102 is sent to the VCM 103 via the inverter 105R.
The electromagnetic brakes 106R and 106L have a role as a parking brake based on a parking brake command and a role as an emergency brake as described later.
Since the electric forklift 1 of the embodiment does not include a service brake such as a hydraulic brake, the wheel is mechanically attached to the wheel except under the condition that the electromagnetic brake for parking is used in the emergency brake described in detail below. There is no function to give braking force. The braking device according to the embodiment is a so-called brake-by-wire braking device.

  In the following description, the left and right traveling motors 104R. In some cases, reference numeral 104 is assigned to 104L, 105 is assigned to the pair of inverters 105R and 105L, and 106 is assigned to the electromagnetic brakes 106R and 106L.

The travel motor 104 is provided with a rotation sensor 104S, and a rotation speed signal SR (see FIG. 3) obtained by the rotation sensor 104S is input to the VCM 103 via the inverter 105R. The VCM 103 calculates the vehicle speed VV based on the rotational speed signal SR. In other words, the rotation sensor 104S functions as a vehicle speed sensor that detects the vehicle speed of the electric forklift 1.
The electromagnetic brake 106 is a negative brake that generates an electromagnetic force when energized to release the brake pad from the disc, and brakes the wheel by pressing the disc with an urging force when de-energized, that is, an electromagnetic braking force is applied to the wheel. is there.

  For example, a three-phase AC motor is used as the traveling motor 104. In this case, the inverters 105R and 105L include a pair of semiconductor switching transistors for each UVW phase. Switching control of the semiconductor switching transistors of each phase is performed by motor drive signals SML and SMR input from the VCM 103 to the inverter 105. Strong electric power is applied from the battery 107 to each phase semiconductor switching transistor of the inverter 105. Necessary electric power is supplied to the coils of each phase by switching control using the motor drive signals SML and SMR, and the traveling motor 104 drives the front wheels with necessary drive torque.

  The VCM 103 calculates a driving torque to be applied to the travel motor 104 based on the input accelerator depression amount signal SAD and brake depression amount signal SBD, and the vehicle speed VV calculated based on the input rotation speed signal SR. The VCM 103 calculates the braking force requested by the operator based on the depression amount of the brake pedal 102A sent from the brake sensor 102. The VCM 103 gives motor drive signals SML and SMR to the semiconductor switching transistors of each phase so that the calculated braking force can be exhibited by the regenerative brake. Thereby, regenerative braking based on the brake depression amount is obtained. When a predetermined condition described later is satisfied, the VCM 103 determines that the braking force obtained by the regenerative braking is insufficient. At this time, the VCM 103 switches the semiconductor switching transistor so as to obtain the maximum regenerative brake, and turns on and off (opens and closes) the electromagnetic brake 106 twice in a predetermined cycle for a predetermined time.

  In FIG. 2, the electric system 100 includes a forward / reverse switch (FRSW) 111, a seat belt switch 112 (Seat Belt SW), a seat switch (Seat SW) 113, a parking brake switch ( PKB SW) 114, key switch (KEY SW) 115, (FTC SW) 116, meter 117, power steering controller (PSCONT) 118, and pump inverter 119.

  A main contactor 121 is disposed between the positive terminal of the battery 107 and the traveling inverters 105 </ b> L and 105 </ b> R, and its relay control terminal is connected to the VCM 103 via a battery switch (BATSW) 122. When the battery switch 122 is operated and the power supply to the relay control terminal is cut off, the main contactor 121 is opened, and the power line between the battery 107 and the traveling inverters 105L and 105R, that is, the motor driving power line is cut off. The When the key switch 113 is turned off, the VCM 103 stops energizing the relay control terminal of the main contactor 121, so that the battery 107 and the traveling inverters 105L and 105R are disconnected.

  An inverter relay 123 is disposed between the positive terminal of the battery 107 and the traveling inverters 105 </ b> L and 105 </ b> R, and the relay control terminal is connected to the VCM 103. When the VCM 103 detects the burn-in of the main contactor 121, the VCM 103 cuts off the power supply to the relay control terminal of the inverter relay 123. As a result, the inverter relay 123 is opened, and the power line between the battery 107 and the traveling inverters 105L and 105R, that is, the power line for driving the semiconductor switching transistor mounted on the inverter is cut off.

  The travel drive control of the electric forklift 1 described above will be described more specifically. The VCM 103 of the electric forklift 1 according to the present embodiment performs drive control of the travel motor 104 based on outputs from the accelerator sensor 101 and / or the brake sensor 102. Hereinafter, drive control will be described separately for power running operation and regenerative operation.

(Power running)
When the operator depresses the accelerator pedal 101A to move forward and backward, the VCM 103 calculates a required torque based on the accelerator depression amount signal SAD and drives and controls the travel motor 104 with reference to the vehicle speed VV. That is, the VCM 103 generates motor drive signals SML and SMR for switching control of the semiconductor switching transistor of the inverter 105 and outputs them to the control terminal of the inverter 105. Switching control of the semiconductor switching transistor of the inverter 105 is performed by the motor drive signals SML and SMR from the VCM 103, the direct current applied to the inverter 105 from the battery 107 is converted into alternating current, and the UVW phases of the traveling motor 104 are energized. The As a result, the traveling motor 104 is driven with the traveling torque requested by the operator, the front wheels rotate, and the forklift travels.

(Regenerative operation)
When the accelerator pedal 101A is released, the torque required by the operator becomes zero, and the traveling motor 104 is driven by the traveling resistance to generate power. At this time, the VCM 103 performs regenerative control by controlling the traveling motor 104 in a so-called power generation mode. In the regenerative control, the VCM 103 controls the regenerative current by driving the semiconductor switching transistor of the inverter 105 in order to apply the regenerative braking force in consideration of the vehicle speed to the traveling motor 104. The AC regenerative current is converted into a DC current by the inverter 105 to charge the battery 107.
When the brake pedal 102A is depressed while the accelerator pedal 101A is released, regenerative control is performed such that a regenerative brake greater than the regenerative brake obtained by releasing the accelerator pedal 101A is obtained. That is, the VCM 103 switches the semiconductor switching transistor of the inverter 105 in accordance with the brake depression amount to obtain a larger regenerative braking force.

  The above is the operation of power running control and regenerative control in a general electric vehicle. In summary, during power running, the inverter 105 converts the direct current from the battery 107 into an alternating current and applies the alternating current to the traveling motor 104, whereby the traveling motor 104 is commensurate with the required torque that is the accelerator depression amount. Driven by travel drive torque. During regenerative operation, rotational torque is transmitted from the wheels to the traveling motor 104, and the traveling motor 104 generates AC power (regenerative power). That is, it generates electricity. The generated AC power is converted into DC power by the inverter 105, and the battery 107 is charged. That is, the generated power of the travel motor is collected in the battery so that the required braking torque based on the depression amount of the brake pedal can be obtained. The charged electric power is used again as travel energy.

  Further, when the VCM 103 detects that the vehicle speed is 12 km / h or more and the depression amount of the brake pedal 102A is a predetermined value or more, in addition to the regenerative control described above, the braking control (specific braking force control) by the electromagnetic brake 106 is performed. I do. In the braking control by the electromagnetic brake 106, at the time of traveling, the brake voltage applied for releasing the brake is cut off for a predetermined time, and the control for energizing the predetermined time after the lapse of the predetermined time is performed at least twice. As a result, a so-called pumping brake control is performed in which the brake pad of the electromagnetic brake 106 clamps the disk for a predetermined time to obtain a mechanical braking force, and the voltage is cut off after the predetermined time has elapsed and the brake pad releases the disk for a predetermined time. Is called. The pumping brake control is not limited to the case where the pumping brake control is performed at least twice. The pumping brake control may be performed once or three times or more, and the number of times can be determined based on the characteristics of the vehicle body of the electric forklift 1.

  FIG. 4 shows the relationship between the depression amount (stroke), the depression force, and the deceleration when the brake pedal 102A is depressed. In FIG. 4, a characteristic L1 indicates the relationship between the depression amount and the depression force of the brake pedal 102A, and characteristics L2-1, L2-2, L2-3, and L2-4 indicate a depression force applied to the brake pedal 102A and a decrease in the electric forklift 1. The relationship with speed is shown. When the brake pedal 102A is depressed while the accelerator pedal 101A is released, regenerative control is performed so that a regenerative brake is obtained with the deceleration indicated by the characteristics L2-1 and L2-2. When the amount of depression of the brake pedal 102A is up to the first predetermined value SB1, the deceleration increases as the amount of depression of the brake pedal 102A increases, as in the characteristic L2-1. When the depression amount of the brake pedal 102A is from the first predetermined value SB1 to the second predetermined value SB2, the deceleration becomes a specific value regardless of the depression amount of the brake pedal 102A, as shown by the characteristic L2-2. . When it is detected that the vehicle speed is, for example, 12 km / h or more and the depression amount of the brake pedal 102A is the second predetermined value SB2 or more, the above-described regeneration is performed so that the deceleration indicated by the characteristics L2-3 and L2-4 is obtained. In addition to the control, braking control by the electromagnetic brake 106 is performed. As shown in the figure, the increase in deceleration is greater in the case of the characteristic L2-3 than in the case where the relationship with the pedal effort is indicated by the characteristic L2-1. The values of the depression amount, the depression force, and the deceleration shown in FIG. 4 are examples, and the actual values may be different from the illustrated values.

With reference to FIG. 5, the processing procedure of the braking control of the VCM 103 will be described. 5 is executed by an arithmetic processing unit such as a CPU of the VCM 103.
In step S1, it is determined whether the accelerator pedal 101A is depressed based on the accelerator depression amount signal SAD. If the determination is affirmative, power running control is executed in step S2. If step S1 is negative, it is determined in step S3 whether the brake pedal 102A is depressed based on the brake depression amount signal SBD. If step S3 is negative, regenerative control by releasing the accelerator pedal 101A is executed in step S4. If step S3 is affirmed, the process proceeds to step S5, where it is determined whether or not the vehicle speed is 12 km / h or higher based on the vehicle speed signal VV calculated by the VCM 103. If step S5 is negative, in step S6, regenerative control is performed in which a regenerative brake larger than the regenerative brake by releasing the accelerator pedal 101A is exhibited (characteristics L2-1 and L2-2 in FIG. 4). That is, the accelerator depression amount is zero based on the accelerator depression amount signal SAD, and the regeneration control based on the brake depression amount signal SBD is executed.

If step S5 is affirmed, that is, if the vehicle speed is determined to be 12 km / h or more, it is determined in step S7 whether or not the brake depression amount is equal to or greater than a second predetermined value SB2. If step S7 is affirmed, in step S8, the braking force obtained by pumping control of the electromagnetic brake 106 in addition to the braking force by the regenerative control based on the depression of the accelerator pedal 101A and the depression amount of the brake pedal 102A is added up. A large braking force is obtained (characteristics L2-3 and L2-4 in FIG. 4).
The braking process when step S5 is affirmed is an emergency braking process. In the emergency braking process, a large braking force as shown by a characteristic L2-3 having a steeper slope than the slope of the characteristic L2-1 of the depression force and the regenerative braking force obtained when the depression amount of the brake pedal 102A is less than the predetermined value SB2. Power is given.

According to the embodiment described above, the following operational effects can be obtained.
(1) The electric system 100 used in the electric forklift 1 including the accelerator pedal 101A, the brake pedal 102A, and the electromagnetic brake 106 that applies an electromagnetic braking force to the wheel based on the parking brake command includes the depression amount of the accelerator pedal 101A A VCM 103 that drives and controls the travel motor 104 based on the depression amount of the brake pedal 102A is provided. The VCM 103 operates the electromagnetic brake 106 when a condition that the depression amount of the brake pedal 102A is equal to or greater than a predetermined value and the vehicle speed is equal to or greater than the predetermined value is satisfied. Therefore, a necessary braking force can be obtained using the electromagnetic brake 106 in an emergency. Moreover, since the electromagnetic brake 106 as a parking brake is also used as an emergency brake, an increase in the number of parts can be suppressed and a braking force in an emergency can be obtained.
(2) When the above condition is satisfied, the VCM 103 executes specific braking control for operating and inactivating the electromagnetic brake 106 at least twice. Therefore, a sufficient braking force can be obtained in an emergency.

(3) When the depression amount of the brake pedal 102A is less than the first predetermined value SB1, the VCM 103 collects and controls the generated power of the travel motor 104 so that a larger deceleration is obtained as the depression amount of the brake pedal 101A is larger. To do. When the depression amount of the brake pedal 101A is from the first predetermined value SB1 to the second predetermined value SB2, the VCM 103 generates electric power generated by the travel motor 104 so that a specific deceleration is obtained regardless of the depression amount of the brake pedal 101A. The collection is controlled. The VCM 103 executes specific braking force control when the amount of depression of the brake pedal 101A is equal to or greater than the second predetermined value SB2 when the vehicle speed is equal to or greater than the predetermined value. Therefore, in an emergency, a high braking force can be obtained by the regenerative brake by the traveling motor 104 and the electromagnetic brake 106.

(4) The VCM 103 executes the control so that the regenerative braking force is greater when the specific power control is executed than when the specific power control is not executed. Therefore, the braking force obtained in an emergency can be increased.

In the embodiment described above, the electric travel control device has been described by taking the electric forklift as an example. Such an electric travel control device can be mounted on various electric work vehicles other than the electric forklift.
Control based on the depression amount of the accelerator pedal and / or the brake pedal is not limited to the embodiment.

  As long as the characteristics of the present invention are not impaired, the present invention is not limited to the above-described embodiments, and other forms conceivable within the scope of the technical idea of the present invention are also included in the scope of the present invention. .

DESCRIPTION OF SYMBOLS 1 ... Electric forklift 100 ... Electric system 101 ... Accelerator sensor 101A ... Accelerator 102 ... Brake sensor 102A ... Brake pedal 103 ... VCM (vehicle control module)
104, 104L, 104R ... travel motor 104S ... rotation sensors 105, 105L, 105R ... inverters 106, 106L, 106R ... electromagnetic brake 107 ... battery

Claims (6)

In an electric travel control device used for an electric vehicle including an accelerator pedal, a brake pedal, and an electromagnetic parking brake device that applies an electromagnetic braking force to a wheel based on a parking brake command,
A control unit that controls driving of the electric motor for traveling based on the depression amount of the accelerator pedal and / or the depression amount of the brake pedal;
The control unit is an electric travel control device that operates the electromagnetic parking brake device when a condition that a depression amount of the brake pedal is a predetermined value or more and a vehicle speed is a predetermined value or more is satisfied. In the electric travel control device according to claim 1,
When the condition is satisfied, the control unit executes a specific braking force control for performing the operation and the non-operation of the electromagnetic parking brake device at least twice. In the electric travel control device according to claim 1 or 2,
The control unit calculates a required torque based on the depression amount of the accelerator pedal, controls an energization current to the electric motor for traveling so as to be the required torque, and requests braking based on the depression amount of the brake pedal. An electric travel control device that calculates torque and collects electric power generated by the electric motor for traveling in a power storage device so as to obtain the required braking torque. In the electric travel control device according to claim 3, which refers to claim 2,
The control unit recovers and controls the generated electric power of the electric motor for traveling so that a larger deceleration is obtained as the amount of depression of the brake pedal is larger in a region where the amount of depression of the brake pedal is less than a first predetermined value; In a region where the amount of depression of the brake pedal is greater than or equal to a first predetermined value and less than a second predetermined value, the generated power is collected and controlled so that a specific deceleration is obtained regardless of the amount of depression of the brake pedal, and the vehicle speed is An electric travel control device that executes the specific braking force control when an amount of depression of the brake pedal becomes equal to or greater than the second predetermined value when the value is greater than or equal to a predetermined value. In the electric travel control device according to claim 4,
The control unit executes the control so that the regeneration control of the generated power when the specific braking force control is executed is such that a larger regenerative braking force is obtained than when the specific braking force control is not executed. Travel control device. An accelerator pedal,
Brake pedal,
An accelerator sensor for detecting the amount of depression of the accelerator pedal;
A brake sensor for detecting the depression amount of the brake pedal;
A vehicle speed sensor for detecting the vehicle speed;
An electromagnetic parking brake device;
An electric motor for traveling;
An electric forklift provided with the electric travel control device according to any one of claims 1 to 5.

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