JP3696542B2 - Electric vehicle - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a straightness maintaining technique for an electric vehicle.
[0002]
[Prior art]
Since a plurality of wheels are provided, and driving wheels among these wheels are driven by an electric motor so that a traveling electric vehicle does not emit exhaust gas, it has been widely spread in recent years.
A one-motor vehicle that drives the left and right drive wheels with one drive axle and one electric motor, and the left drive wheel is driven with the left electric motor and the right drive wheel is driven with the right electric motor. Although the two-motor type vehicle is put into practical use, the latter two-motor type vehicle is easy to turn, but the difference in rotational speed between the left and right drive wheels is likely to occur, and the straightness is difficult. If the road surface is bad and one of the driving wheels receives resistance due to the unevenness of the road surface, it may not be able to go straight ahead.
[0003]
For example, Japanese Patent Application Laid-Open No. 59-17807 “Electric Vehicle” has proposed an electric vehicle that can be driven straight regardless of the road surface condition. According to the description in the upper left column, lines 4 to 10 of the second publication of this publication, this electric vehicle is "... the load of the left and right wheel drive motors changes and the load is applied to one of the motors and the rotational speed thereof. Since the actual running rotation speed of one motor is further reduced by the correction of the straight running correction circuit, the motor drive output from the power running control circuit of one motor is increased and the rotation speed is increased. You can go straight without it. "
[0004]
[Problems to be solved by the invention]
The technology of the above publication increases the difference between the actual rotational speed and the command rotational speed by forcibly lowering the rotational speed of the wheel that has decreased in rotational speed due to an increase in load, and promotes the power running control to increase the rotational speed. Lower. That is, in one wheel, control is performed in the order of rotation speed decrease detection → rotation speed forced decrease → rotation speed forced increase, and the other wheel remains at a high rotation speed.
[0005]
As a result, the rotation speeds of the left and right wheels coincide, but one wheel is significantly slower until then (although it is a short time). If one wheel is significantly slowed down, the car will turn. That is, this car frequently undergoes a small turn, and smooth running cannot be expected.
[0006]
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an electric vehicle that can maintain smooth running and keep straight running performance even when a load acting on one drive wheel increases.
[0007]
[Means for Solving the Problems]
Claim in order to achieve the above object 1 is provided with a directional speed lever can be set and speed control of the front and rear direction and high at low speed Rutotomoni one lever each with an electric motor to the left and right of the machine body, the directional speed lever In the electric vehicle that drives the left and right drive wheels with the electric motor by operating the electric vehicle, the electric vehicle has a straight travel command condition and a condition that the actual rotational speed of the electric motor has not reached the target rotational speed, When the three conditions of the control signal output generated to bring the actual rotational speed closer to the target rotational speed reach the control signal output upper limit are satisfied, the control output signal upper limit can be corrected downward from the upper limit of the control output signal the control signal limit values are subtracted gradually with gradually controller for performing downward correction processing to reduce the control signal output upper limit control output signal upper limit value by correcting down the control output signal If it does not reach the control signal output upper limit is characterized in that it does not perform the downward revision process.
[0008]
If the rotation of the electric motor falls during straight running, it is possible that the running is hindered by uphill slopes, road surface irregularities and obstacles, and a large resistance is generated in the drive system. Nevertheless, the aircraft may turn right or left.
Therefore, when the above three conditions are satisfied, the upper limit of the control signal output is corrected downward.
[0009]
The control signal output upper limit defines the maximum rotational speed of the electric motor at that time. Therefore, if the control signal output upper limit is corrected downward, the maximum rotation speed of the electric motor is lowered. Such downward correction continues until the rotation speeds of the left and right electric motors match. As a result, the rotation speeds of the left and right electric motors coincide with each other, so that straightness can be maintained.
[0010]
When the control signal output has not reached the upper limit, there is still room for speed increase, and the present invention is not applied. Therefore, the third condition was added.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the accompanying drawings. Note that “front”, “rear”, “left”, “right”, “upper”, and “lower” follow the direction viewed from the operator, L indicates the left side, and R indicates the right side. The drawings are viewed in the direction of the reference numerals.
[0012]
FIG. 1 is a plan view of a snowplow according to the present invention. A snowplow 10 as an electric vehicle is equipped with an engine 12 in a body 11 and an auger 13 and a blower 14 as a working part at the front of the body 11. The crawlers 15 </ b> L and 15 </ b> R are arranged on the left and right sides of the machine body 11, and the operation panel 16 is arranged on the rear part of the machine body 11, which is a walking work machine that an operator takes from behind the operation panel 16. Hereinafter, the main part will be described in detail. The operation panel 16 will be described in detail with reference to FIG.
[0013]
The generator 17 is rotated by a part of the output of the engine 12, and the obtained electric power is supplied to a battery (see reference numeral 43 in FIG. 4) disposed below the operation panel 16 and to the left and right traveling motors described later. .
The remainder of the output of the engine 12 is used for rotation of the blower 14 and the auger 13 as working portions via the electromagnetic clutch 18 and the belt 19. The auger 13 has a function of collecting the snow accumulated on the ground in the center, and the blower 14 receiving the snow projects the snow to a desired position around the body 11 through the shooter 21. An auger housing 22 is a cover member that surrounds the auger 13.
[0014]
The left crawler 15L is wound around the drive wheel 23L and the idle wheel 24L. In the present invention, the drive wheel 23L is rotated forward and backward by the left travel motor 25L. The right crawler 15R is also wound around the drive wheel 23R and the idle wheel 24R. In the present invention, the drive wheel 23R is rotated forward and backward by the right travel motor 25R.
[0015]
In the conventional snow remover, one engine (gasoline engine or diesel engine) covers the working system (auger rotation system) and the traveling system (crawler drive system). The auger rotating system is driven, and the traveling system (crawler driving system) is driven by the electric motor (traveling motors 25L and 25R).
Based on the idea that an electric motor is appropriate for fine travel speed control, turning control, and forward / reverse switching control, while a working internal combustion system that is subject to sudden load fluctuations is appropriate. I did that.
[0016]
2 is a view taken in the direction of the arrow 2 in FIG. 1. The operation panel 16 includes a main switch 28, an engine choke 29, a clutch operation button 31, and the like on the side surface in front of the operation box 27. A snow throwing direction adjusting lever 32, an auger housing attitude adjusting lever 33, a directional speed lever 34 related to the traveling system, and an engine throttle lever 35 related to the working unit system are provided. And a grip 36L, a left turning operation lever 37L, and a travel preparation lever 38 on the left of the operation box 27.
[0017]
Although the left and right turning operation levers 37L and 37R are similar to the brake lever, a complete braking effect cannot be obtained as will be described later. Since it is used to turn the aircraft by turning the traveling motors 25L, 25R by operating, it is called a turning operation lever instead of a brake lever.
[0018]
The main switch 28 is a well-known switch that can start the engine by inserting and turning the main key. The engine choke 29 can be pulled to increase the concentration of the air-fuel mixture. The snow throwing direction adjustment lever 32 is a lever operated when changing the direction of the shooter (reference numeral 21 in FIG. 1), and the auger housing attitude adjustment lever 33 is used when changing the attitude of the auger housing (reference numeral 22 in FIG. 1). It is a lever that operates.
The operation of the other members will be described with reference to FIG.
[0019]
FIG. 3 is a view taken in the direction of arrow 3 in FIG. 2, and the angle of the arm 39a of the potentiometer 39L can be rotated to the position of the imaginary line by grasping the left turning operation lever 37L. The potentiometer 39L is a device that emits electrical information corresponding to the rotational position of the arm 39a.
[0020]
The travel preparation lever 38 is a member that acts on the switch means 42, and the switch means 42 is turned on when the spring 41 is pulled to reach the state shown in the figure (free state). If the travel preparation lever 38 is lowered clockwise with the operator's left hand, the switch means 42 is turned off. In this way, whether or not the travel preparation lever 38 is gripped can be detected by the switch means 42.
[0021]
FIG. 4 is a control system diagram of the snowplow according to the present invention, and shows devices and information transmission paths in the control unit 44 built in or attached to the operation panel. In general, squares indicate devices and circles indicate drivers. The engine 12, the electromagnetic clutch 18, the blower 14, and the auger 13 surrounded by an imaginary line frame are the working unit system 45, and the others are the traveling system. 43 is a battery.
In addition, although the flow of instructions is shown for convenience in the control unit 44 by a broken line, this is merely a reference description.
[0022]
First, the operation of the working unit system will be described.
By inserting a key into the main switch 28 and turning it to the start position, the engine 12 is started by rotation of a cell motor (not shown).
Since the engine throttle lever 35 is connected to the throttle valve 48 by a throttle wire (not shown), the opening degree of the throttle valve 48 can be controlled by operating the engine throttle lever 35. Thereby, the rotation speed of the engine 12 can be controlled.
[0023]
By grasping the travel preparation lever 38 and operating the clutch operation button 31, the electromagnetic clutch 18 can be connected and the blower 14 and the auger 13 can be rotated at the will of the operator.
Note that the electromagnetic clutch 18 can be disengaged by either making the travel preparation lever 38 free or operating the clutch operation button 31.
[0024]
Next, the operation of the traveling system will be described. The snowplow of the present invention includes left and right electromagnetic brakes 51L and 51R as brakes corresponding to parking brakes for ordinary vehicles, and these electromagnetic brakes 51L and 51R are controlled by the control unit 44 during parking. Is in a state. Therefore, the electromagnetic brakes 51L and 51R are released by the following procedure.
[0025]
When the two conditions of the main switch 28 being in the start position and the travel preparation lever 38 being held are satisfied and the directional speed lever 34 is switched to forward or reverse (described in FIG. 5), the electromagnetic brake 51L and 51R are in an open (non-brake) state.
[0026]
FIG. 5 is an explanatory diagram of the operation of the directional speed lever employed in the present invention. The directional speed lever 34 can be reciprocated as shown by arrows (1) and (2) by the operator's hand, and the “neutral range”. When the vehicle is further moved to the “advance” side, the vehicle can be advanced, and in the “advance” region, speed control can also be performed so that Lf is a low-speed advance and Hf is a high-speed advance. Similarly, the vehicle can be moved backward by tilting from the “neutral range” to the “reverse” side, and in the “reverse” region, speed control can also be performed so that Lr is reverse at low speed and Hr is reverse at high speed. In this example, as indicated at the left end of the figure, the potentiometer responded to the position so that the maximum reverse speed was 0 V (volts), the maximum forward speed was 5 V, and the neutral range was 2.3 V to 2.7 V. Generate voltage.
The front / rear direction and the high / low speed control can be set with one lever, so the direction speed lever 34 is named.
[0027]
Returning to FIG. 4, the control unit 44 that has obtained the position information of the directional speed lever 34 from the potentiometer 49 rotates the left and right traveling motors 25L and 25R via the left and right motor drivers 52L and 52R. The rotation speed is detected by the rotation sensors 53L and 53R, and feedback control is executed based on the signal so that the rotation speed becomes a predetermined value. As a result, the left and right drive wheels 23L, 23R rotate in a desired direction at a predetermined speed and enter a traveling state.
[0028]
Braking while driving is performed according to the following procedure. In the present invention, the motor drivers 52L and 52R include regenerative brake circuits 54L and 54R.
[0029]
In general, the electric motor rotates by supplying electric energy from the battery to the electric motor. On the other hand, a generator is a means for converting rotation into electrical energy. Therefore, in the present invention, the electric motors are used to change the traveling motors 25L and 25R to generators to generate electric power. If the generated voltage is higher than the battery voltage, electric energy can be stored in the battery 43. This is the operating principle of the regenerative brake.
[0030]
The degree of grip of the left turning operation lever 37L is detected by the potentiometer 39L, and the control unit 44 activates the left regenerative brake circuit 54L in response to the detection signal, and decreases the speed of the left travel motor 25L.
The degree of grip of the right turning operation lever 37R is detected by the potentiometer 39R, and the control unit 44 operates the right regenerative brake circuit 54R in response to the detection signal to reduce the speed of the right travel motor 25R.
That is, it can be turned left by grasping the left turning operation lever 37L, and can be turned right by grasping the right turning operation lever 37R.
[0031]
And driving | running | working can be stopped by either of the following.
Return the directional speed lever 34 to the neutral position.
Release the travel preparation lever 38.
The main switch 28 is returned to the off position.
[0032]
If the main switch 28 is returned to the OFF position after the stop, the electromagnetic brakes 51L and 51R are brought into a brake state, which is the same as the parking brake is applied.
[0033]
Next, a control method when the snow remover of the present invention travels straight will be described.
FIG. 6 is a flow chart of straight traveling control according to the present invention, where STxx indicates a step number. This control is performed under the straight travel command condition. The straight travel command condition can be recognized when both the left and right turning operation levers 37L and 37R (see FIG. 4) are in an off state (a state in which they are not gripped).
ST01: Read the control signal output upper limit Dmax. As the initial value, 100% or a predetermined value (for example, 90%) is adopted.
[0034]
ST02: The control unit outputs a control signal so that the target motor rotational speed Mn corresponding to the position of the directional speed lever is reached, and operates the left traveling motor. However, the control signal output reaches a peak at the control signal output upper limit Dmax.
ST03: The actual motor rotation speed Nml is measured. What is necessary is just to measure with the rotation sensor 53L of FIG.
ST04: Check whether or not the actual rotational speed Nml is equal to the target motor rotational speed Mn. If they are equal, there is no need to change the state, so return to the start. If the actual rotation speed Nml is larger than the target motor rotation speed Mn, it is determined that the speed is exceeded, and the process proceeds to ST05. Alternatively, if the actual rotation speed Nml is smaller than the target motor rotation speed Mn, it is determined that the speed is insufficient and the process proceeds to ST06.
[0035]
ST05: Perform deceleration control to correct overspeed, and return to start.
ST06: Increase speed control is started to correct the shortage of speed.
ST07: The control signal output Dul for executing the speed increase control is read. This signal output Dul corresponds to PI output for PI control and PID output for PID control. The larger the difference between the target value and the actual value, the larger the signal output. Generally, there is a difference between the target value and the actual value. If it exceeds, the signal output becomes the upper limit.
[0036]
ST08: Therefore, it is checked whether or not the control output signal Dul is the control signal output upper limit Dmax. If NO (when it is not the upper limit), the process proceeds to return, and if YES, the process proceeds to ST09.
ST09: The upper limit of the left control signal output is corrected to (Dmax-β), and this is set to Dmaxl. That is, the upper limit of the left control signal output is corrected downward. β is, for example, 1%.
[0037]
Although the left traveling motor has been described above, the same control is performed for the right traveling motor as follows.
ST10: The control unit outputs a control signal so that the target motor rotational speed Mn corresponding to the position of the directional speed lever is obtained, and operates the right traveling motor. However, the control signal output reaches a peak at the control signal output upper limit Dmax.
ST11: The actual motor rotation speed Nmr is measured. What is necessary is just to measure with the rotation sensor 54R of FIG.
ST12: It is checked whether or not the actual rotational speed Nmr is equal to the target motor rotational speed Mn. If they are equal, there is no need to change the state, so return to the start. If the actual rotational speed Nmr is larger than the target motor rotational speed Mn, it is determined that the speed is exceeded, and the process proceeds to ST13. Alternatively, if the actual rotational speed Nmr is smaller than the target motor rotational speed Mn, it is determined that the speed is insufficient and the process proceeds to ST14.
[0038]
ST13: Deceleration control is performed to correct overspeed, and the process returns to the start.
ST14: The speed increasing control is started to correct the shortage of speed.
ST15: Read the control signal output Dur when the acceleration control is performed.
[0039]
ST16: Therefore, it is checked whether or not the control output signal Dur is the control signal output upper limit Dmax. If NO (when it is not the upper limit), the process proceeds to return, and if YES, the process proceeds to ST17.
ST17: The upper limit of the right control signal output is corrected to (Dmax−β), and this is set as Dmaxr. That is, the upper limit of the right control signal output is corrected downward.
[0040]
ST18: The left control signal output upper limit Dmaxl corrected as described above is compared with the right control signal output upper limit Dmaxr.
ST19: The smaller Dmaxl is set as a new control signal output upper limit (Dmax).
ST20: The smaller (including equal) Dmaxr is set as a new control signal output upper limit (Dmax).
[0041]
When returning to the start after performing ST19 or ST20, the control signal output upper limit Dmax in the next ST01 becomes a value smaller by β than the previous time. If this is repeated, the maximum motor rotational speed gradually decreases, but this treatment results in the right and left actual rotational speeds matching each other, and straightness is restored.
[0042]
That is, if the present invention is arranged, the left and right sides of the airframe 11 shown in FIG. 1 are provided with traveling motors 25L and 25R as electric motors, and the driving motors 25L and 25R respectively drive the left and right drive wheels 23L and 23R. In the snow remover 10 as an electric vehicle, the snow remover 10 includes a straight travel command condition, a condition that the actual rotational speed of the electric motor has not reached the target rotational speed (ST04, ST12 in FIG. 6), and an actual The control signal output upper limit Dmax is gradually increased when the three conditions, that is, the condition that the control signal output generated to bring the rotational speed close to the target rotational speed has reached the upper limit (ST08, ST16 in FIG. 6) are satisfied. A control unit (reference numeral 44 in FIG. 4) for performing a downward correction process (ST19, ST20 in FIG. 6) is provided.
[0043]
The reason why the actual rotational speed falls below the target rotational speed during straight traveling is that the road surface is extremely uneven, or that the vehicle has come uphill.
In particular, if a phenomenon occurs in which the actual rotational speed falls below the target rotational speed on either the left or right side due to unevenness on the road surface, the snow blower may turn to the right or to the left regardless of a straight ahead command.
The present invention is characterized in that the rotational speed of the electric motor is lowered by lowering the upper limit of the control signal output, and as a result, the actual rotational speeds on the left and right sides are matched to maintain straightness.
[0044]
The electric vehicle to which the present invention is applied is not limited to a snowplow, and any type can be used as long as it is an electric vehicle such as an electric vehicle or an electric golf cart.
[0045]
【The invention's effect】
The present invention exhibits the following effects by the above configuration.
According to the first aspect of the present invention, the upper limit of the control signal output related to the control of the electric motor is corrected downward when the three conditions are satisfied. If the control signal output upper limit is lowered, the maximum rotation speed of the electric motor is lowered. Such downward correction continues until the rotation speeds of the left and right electric motors match. As a result, the rotation speeds of the left and right electric motors coincide with each other, so that straightness can be maintained.
[Brief description of the drawings]
FIG. 1 is a plan view of a snowplow according to the present invention. FIG. 2 is a view taken along the arrow 2 in FIG. 1. FIG. 3 is a view taken along the arrow 3 in FIG. FIG. 5 is a diagram for explaining the operation of a directional speed lever employed in the present invention. FIG. 6 is a flow chart for straight travel control according to the present invention.
DESCRIPTION OF SYMBOLS 10 ... Electric vehicle (snowblower), 11 ... Airframe, 23L, 23R ... Drive wheel, 25L, 25R ... Electric motor (travel motor), 44 ... Control part.

Claims (1)

Comprising a directional speed lever, each can be set and speed control of the front and rear direction and high at low speed Rutotomoni one lever includes an electric motor to the left and right of the machine body, left and right driven by the electric motor by operating the directional speed lever In an electric vehicle that drives each wheel,
This electric vehicle has a straight travel command condition, a condition that the actual rotational speed of the electric motor does not reach the target rotational speed, and a control signal output generated to bring the actual rotational speed closer to the target rotational speed. When the three conditions of reaching the upper limit are satisfied, the control output signal upper limit value is gradually corrected downward to the control signal upper limit obtained by subtracting an arbitrary control signal lower correction value from the control output signal upper limit. A control unit for performing downward correction processing to gradually reduce the upper limit of the control signal output by ,
The electric vehicle , wherein the downward correction process is not performed when the control output signal does not reach the control signal output upper limit .

Images