JP2000102116A - Compact electric vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively prevent an on-vehicle battery from being overcharged at the time of going downhill, by decelerating the traveling speed with a decelerating means if a detected battery voltage is judged to exceed a first given value. SOLUTION: If a battery voltage is judged to exceed a given value, an electric motor 28 is used as a generator when traveling in deceleration on a downhill, for instance, and a battery 38 is charged while the traveling speed is decelerated with regenerative braking. But, charging voltage increases on a long downhill. If the battery voltage exceeds an overcharged voltage, therefore, duty ratio is made to decline gradually. Specifically, the duty ratio is made to decrease continuously by 1%, for example, so that the traveling speed decreases by about 2 km/h during the given period of time. This structure can effectively prevent an on-vehicle battery from being overcharged at the time of going downhill. The car does not have to be stopped. Simply needed is the decrease of the traveling speed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a small electric vehicle used as an electric wheelchair or a golf cart.

[0002]

2. Description of the Related Art The above-mentioned compact electric vehicle is disclosed in U.S. Pat. No. 4,729,447 or Japanese Patent Laid-Open No. 10-1.
A technique described in Japanese Patent No. 65454 is known. The technique described in U.S. Pat. No. 4,729,447 proposes to provide a safeguard mechanism near an operation lever for protecting an occupant.

In the technique described in Japanese Patent Application Laid-Open No. H10-165454, when the traveling state is switched from forward to reverse or from reverse to forward, the traveling direction is changed after stopping for a predetermined time, so that the occupant can feel safe. A technique to change the direction is proposed.

[0004]

A vehicle of this type generally includes an electric motor that is energized from an on-board battery to drive wheels, and controls the electric motor in accordance with an instruction of an occupant in a forward direction or a reverse direction. When the vehicle decelerates on a downhill road or the like, the vehicle-mounted battery is charged while the traveling speed is reduced by the regenerative brake.

[0005] As a result, when the vehicle is driven on a long-distance downhill road at a relatively high speed, the vehicle-mounted battery may be overcharged.
In such a case, the vehicle is normally stopped from running, but stopping the running is inconvenient for the occupant, and is an obstacle in case of emergency slamming.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-mentioned problems and to provide an electric motor for driving wheels by being energized from an on-vehicle battery. In a small vehicle that travels in the direction and charges the vehicle-mounted battery while decelerating the running speed with regenerative braking during deceleration such as when descending a slope, a small-sized vehicle that effectively prevents overcharging of the vehicle-mounted battery during a downhill. It is intended to provide an electric vehicle.

[0007]

According to a first aspect of the present invention, there is provided an electric motor which is driven by a vehicle-mounted battery to drive wheels, and controls the electric motor in accordance with an instruction of an occupant. In a small electric vehicle that travels in the forward or reverse direction and recharges the on-board battery with regenerative braking when descending a hill, battery voltage detecting means for detecting the voltage of the on-board battery; 1 and a deceleration means for decelerating a traveling speed when it is determined that the detected battery voltage exceeds the first predetermined value. .

Thus, the vehicle is provided with an electric motor which is energized by a vehicle-mounted battery and drives the wheels. The electric motor is driven and controlled in accordance with an instruction of an occupant to travel in a forward direction or a reverse direction. In a small-sized vehicle that charges the vehicle-mounted battery while reducing the traveling speed by regenerative braking, it is possible to prevent the vehicle-mounted battery from being overcharged when descending a hill. Further, since it is sufficient to reduce the traveling speed and there is no need to stop the traveling of the vehicle, it is convenient for the occupants and does not cause any trouble even in the event of an emergency.

According to a second aspect of the present invention, the deceleration means includes:
The traveling speed is reduced every predetermined time.

As a result, if the vehicle is suddenly decelerated, overcharging may be caused. However, the gradual operation does not cause overcharging and does not give a feeling of discomfort to the occupant.

According to a third aspect of the present invention, the vehicle further comprises an accelerator lever for instructing the vehicle to travel in a forward direction or a reverse direction, and the deceleration means is provided when the accelerator lever is turned on after the accelerator lever is turned off. It was configured to return to the vehicle speed.

[0012] Thereby, without giving a sense of incongruity,
The intention of the occupant can be reflected.

[0013]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a top view of a small electric vehicle according to the present invention, FIG. 2 is a reduced side view thereof, FIG. 3 is a side view thereof, and FIG. 4 is a rear view thereof.

In the following, a small electric vehicle 10 according to the present invention has a scooter-like appearance having a main frame 12. A handle pipe 14 is attached to a front end of the main frame 12, and a steering wheel 16 is attached above the handle pipe 14.

At the other end, the handle pipe 14 is connected to two front wheels 22, 22 via a gear mechanism 18, and steers the front wheels 22 in a direction and an angle corresponding to the rotation of the steering wheel 16.

The main frame 12 has a post 2 at the rear end.
4, and a seat 26 on which an occupant sits is attached above the seat 4. The illustration of the sheet is omitted in FIGS. 3 and 4.

A (power generation) electric motor 28 is accommodated in a lower portion of the seat 26. The output of the electric motor 28 is transmitted to the axle 34 via the electromagnetic brake 30, and drives two rear wheels 36, 36 attached to both ends thereof.

The electric motor 28 has two batteries (vehicle power source) 3 housed near the handle pipe 14 on the front wheel side.
8, 38 (each having a capacity of 12 V), and is supplied with a battery voltage to rotate. Thus, the small electric vehicle 1
0 is configured as a four-wheeled vehicle, and a battery is arranged between the front wheels to improve stability. Note that reference numeral 40 is
Shows the main fuse box.

Further, as shown in FIG. 3, a headlight 44 is provided on the front of the vehicle, and blinker lights 46, 46 for indicating directions are provided on both side surfaces thereof. As shown in FIG. 4, two reflectors 4 are provided at the rear of the vehicle.
8, 48 are arranged.

The electric motor 28 is controlled by a control unit (electronic control unit) 50 which is disposed adjacent to the electric motor 28 in a space below the rear wheel side seat 26 (the reference numeral 50 denotes the control unit in more detail). Although a box is shown, a control unit is indicated by reference numeral 50 for convenience of illustration). Control unit 50
Has a microcomputer.

FIG. 5 is a circuit diagram showing details of the control unit 50. Although omitted in FIG. 5, the control unit 50 includes a motor driving circuit 5 as shown in FIG.
4 is provided. The motor drive circuit 54 includes a bridge circuit including four FETs (switching elements) A, B, C, and D.

In FIG. 6, when two opposing FET elements A and D are turned on and a source current flows as shown by an arrow (solid line), the electric motor 28 rotates forward in a direction shown by an arrow (solid line). The small electric vehicle 10 in the forward direction.

On the other hand, when the two opposing FET elements B and C are turned on and a source current flows as shown by the arrow (broken line), the electric motor 28 rotates in the direction shown by the arrow (broken line), and The vehicle 10 travels in the reverse direction.

Although not shown in FIG. 5 and the like, the control unit 50 includes a detection resistor, and detects the battery voltage VB from the voltage between both ends. Further, the motor application voltage VM is calculated by subtracting the product of the motor conduction current IM and the ON resistance RON of the FET from the detected battery voltage VB. That is, the motor applied voltage is calculated as follows. VM = VB- (RON × IM)

As will be described later, the electric motor 28 functions as a generator and charges the battery 38 in a decelerating operation state such as downhill. Further, the battery 38 can be charged from an external AC power supply via the charger 56.

A main control panel 58 is arranged near the steering wheel 16.

FIG. 7 is an enlarged top view of the main control panel 58, and FIG. 8 is an explanatory view showing the display of the panel portion (in FIG. 5, it is shown as "PANEL"). The illustration of the steering wheel 16 is omitted in FIG.

As shown, the main control panel 5
At the bottom of 8, a rotary key switch (power switch) 6
2 are provided. The key switch 62 is connected to the electric motor 28.
Is provided in a motor drive circuit 54 connecting the battery 38 to the battery 38.

The key switch 62 disconnects the connection between the battery 38 and the electric motor 28 when the occupant is turned to the "stop" position shown in FIG. 28.

7 and 8, a forward / reverse select switch 64 for the occupant to select "forward" (forward travel) or "rearward" (reverse travel).
Is provided.

A speed volume 66 is provided above the key switch 62. The speed volume 66
The voltage Vsv is output according to the position turned between the numbers 2 and 6 by the occupant. That is, as shown in FIG.
A value around 8 V is output from the vicinity, and the traveling speed is set to a value corresponding to 0 km / h to a value corresponding to 6.5 km / h accordingly.

Further, as shown in FIG. 7, an accelerator volume 68 (accelerator lever) is disposed at the right end of the main control panel 58. Accelerator volume 68
7, the free end of which is configured to be movable in the vertical direction on the paper surface in FIG. 7, and is moved downward by the occupant to instruct the vehicle to travel forward or backward.

The accelerator volume 68 generates a voltage Vav corresponding to the downward movement of the drawing sheet as shown in FIG.
Output. The output voltage Vav is equal to the starting volume voltage Vav.
When it becomes equal to or longer than s, it is determined that the accelerator is on, and the traveling control is started.

The traveling speed of the small electric vehicle 10 is set to a value obtained by multiplying the output voltage (volume position) of the speed volume 66 by a predetermined ratio (acceleration ratio) based on the output voltage (volume position) of the accelerator volume 68. Controlled.

More specifically, the duty ratio (in PWM control) of the FET of the motor drive circuit 54 is determined by the control unit described above so that the traveling speed becomes the value, and the motor is driven by the duty. When the accelerator volume 68 is turned off, the small electric vehicle 10 decelerates in a predetermined deceleration pattern and stops.

As shown in FIG. 5, a rotary encoder (ENCODER) 72 is arranged in the electric motor 54, and outputs a signal proportional to the vehicle traveling speed through the motor rotation speed.

Above the main control panel 58, five indicators 74 made of LED elements are provided. In FIG. 5 and the like, these five indicators 74 are set to N
O. 1 to NO. 5 is indicated. This indicator 74
Is used for displaying the remaining amount of the battery 38 and the like.

Next, the operation of the illustrated small electric vehicle 10, more specifically, the operation of preventing the battery 38 from being overcharged at the time of going down a slope will be described.

FIG. 11 is a flow chart showing the operation. It should be noted that the program shown in FIG.
00 msec).

FIG. 12 is an explanatory diagram of the battery voltage for explaining the operation.

In the following, it is determined in S10 whether the above-mentioned charger 56 is turned on, that is, whether or not the battery 38 is charged via the charger 56. If the result is affirmative, the subsequent processing is skipped.

When the result in S10 is NO, the program proceeds to S12,
It is determined whether or not the bit of the flag FV is set to 1. Since the initial value of the bit of this flag is set to 0, the result is denied in the first program loop, and the process proceeds to S14, where the battery voltage (battery terminal voltage) VB is detected.

Next, the program proceeds to S16, in which it is determined whether or not the detected battery voltage VB exceeds a predetermined value VBREF (for example, 30 V). If the result is negative, the subsequent processing is skipped. To set the bit of the flag FV to 1.

That is, setting the bit of this flag to 1 means that the battery voltage has exceeded a predetermined voltage. If the result in S12 is affirmative, the processing up to S18 is skipped.

The increase in the battery voltage will be described. In the illustrated vehicle 10, the electric motor 28 is used as a generator during deceleration running on a downhill or the like, and the battery 38 is charged while the running speed is reduced by regenerative braking.

When traveling downhill, the traveling speed is constant, for example, 6 km.
/ H, but if the downhill road is long, the charging current may increase and the battery 38 may be overcharged.

To explain this, in the small electric vehicle 10, the electric motor 28 is controlled as follows according to the traveling road conditions. The following are representative examples.

Road condition Speed VB IB VM IM Duty ratio Flat 6km / h 24.9V 5.4A 20.0V 5.6A 80% Uphill 6km / h 24.2V 33.0A 22.6V 32.0A Almost 100% Downhill 6km / h 26.2V- 9.0A 16.4V -18.0A 68%

In the above, IB indicates a battery discharge (charge) current. Further, as described above, VM indicates the motor applied voltage, and IM indicates the motor energizing current. Further, a negative value of the current indicates a value flowing in a direction for charging the battery 38.

As described above, the battery 38 is charged when going downhill, but when the downhill road is long, the charging voltage also rises, and as shown by a broken line in FIG.
A situation exceeding V may also occur.

Therefore, in this small electric vehicle 10,
The allowable limit of the battery voltage VB is set to 30 V, and when the battery voltage VB exceeds the overcharge voltage, the duty ratio is reduced as follows.

Road condition Speed VB IB VM IM Duty ratio Downhill 6km / h 26.2V -9.0A 16.4V -18.0A 68% Downhill 4km / h 33.2V -6.0A 9.2V -29.0A 38% Downhill 2km / h 28.0V -1.2A 3.1V -29.0A 13%

In this case, if the traveling speed, that is, the duty ratio, is suddenly decreased, the voltage will suddenly increase.
The duty ratio is gradually reduced.

Specifically, when the battery voltage VB exceeds 30 V, the traveling speed gradually decreases from 6 km / h to 4 km / h for a predetermined time (for example, 10 sec).
The duty ratio is reduced so as to gradually decrease from / h to 2 km / h during a predetermined time (for example, 10 sec).

That is, the traveling speed is set to a predetermined time (10 sec).
, The duty ratio is gradually reduced continuously, for example, by 1% so as to reduce 2 km / h.

At this time, a buzzer (not shown) is actuated to notify the occupant.

When the vehicle immediately returns to the traveling speed before deceleration (6 km / h) after the charging voltage drops, the occupant gives a sense of incongruity. Therefore, the accelerator volume 68 is once turned off by the occupant and then turned on. At this time, the running speed was restored to the running speed before deceleration (6 km / h).

Returning to the description of FIG. 11, the program then proceeds to S20, in which it is determined whether the bit of the flag FT has been set to "1". Since the initial value of this flag bit is set to 0, the flag is negated in the first program loop and S2
Proceed to 2 to start a timer (up counter) T.

Then, the program proceeds to S24, in which the bit of the flag FT is set to "1". That is, the bit of this flag is set to 1
Setting to means that the timer is started and time measurement is started. If the result in S20 is affirmative, the processing up to S24 is skipped.

Then, the program proceeds to S26, in which it is determined whether the timer value T has exceeded a predetermined value TREF. In this control, as described above, the traveling speed is gradually increased to 2k over 10 seconds.
Since the duty ratio is continuously reduced, for example, gradually by 1% so as to decrease by m / h, the predetermined value TREF
HA is set by obtaining a value corresponding to a reduction time per 1% duty.

When the result in S26 is negative, the subsequent processing is skipped. When the result is affirmative, the process proceeds to S28, in which the duty ratio is reduced by 1% to reduce the traveling speed (at the same time, the occupant is warned).

Next, the flow proceeds to S30, where the bit of the flag FV is reset to 0, and the flow proceeds to S32, where the flag FT is set.
Is reset to 0.

Then, the program proceeds to S34, in which it is determined whether or not the output Vav of the accelerator volume 68 has become lower than the starting volume voltage Vags, that is, whether or not the accelerator has been turned off.

When the result in S34 is negative, the subsequent processing is skipped, and when the result is affirmative, the process proceeds to S36, where the bit (initial value 0) of the flag FVA is set to 1 and S3
Proceeding to 8, it is determined whether the output Vav of the accelerator volume 68 has exceeded the starting volume voltage Vavs, that is, whether the accelerator has been turned on again.

When the result in S38 is negative, the subsequent processing is skipped. When the result is affirmative, the process proceeds to S40, and it is determined whether or not the bit of the flag FVA is set to "1". That is, it is determined whether or not the accelerator is once turned off.

When the result in S40 is negative, the subsequent processing is skipped. When the result is affirmative, the process proceeds to S42, in which the vehicle returns to the normal running control, that is, the running control before deceleration. Next, the process proceeds to S44, where the bit of the flag FVA is reset to 0.

Since the present embodiment is configured as described above, it is possible to effectively prevent the vehicle-mounted battery from being overcharged when going downhill. Further, since it is sufficient to reduce the traveling speed and there is no need to stop the traveling of the vehicle, it is convenient for the occupants and does not cause any trouble even in the event of an emergency.

As described above, this embodiment is provided with the electric motor 28 which is energized by the on-board battery (battery 38) and drives the wheels. The electric motor 28 is driven and controlled in accordance with the instruction of the occupant in the forward or backward direction. In a small electric vehicle 10 that travels and charges the vehicle-mounted battery with a regenerative brake when descending a hill, a battery voltage detecting means (S14) for detecting the voltage of the vehicle-mounted battery, wherein the detected battery voltage is a first predetermined value Battery voltage determining means (S16) for determining whether or not the voltage exceeds VBREF; and when it is determined that the detected battery voltage exceeds the first predetermined value, the traveling speed is reduced. The duty ratio output to the motor drive circuit 54 of the voltage motor 38 via the motor 54 is reduced to reduce the traveling speed. It was composed as comprising a reduction means (S18 from S44).

[0070] With this arrangement, an electric motor is provided which is energized by a vehicle-mounted battery and drives the wheels. The electric motor is driven and controlled in accordance with the instructions of the occupant to travel in the forward or reverse direction. In a small-sized vehicle that charges the vehicle-mounted battery while reducing the traveling speed by regenerative braking, it is possible to prevent the vehicle-mounted battery from being overcharged when descending a hill. Further, since it is sufficient to reduce the traveling speed and there is no need to stop the traveling of the vehicle, it is convenient for the occupants and does not cause any trouble even in the event of an emergency.

The deceleration means operates for a predetermined time TREF.
The driving speed of the voltage motor 38 via the motor driving circuit 54
The driving speed is reduced by reducing the duty ratio outputted to the vehicle.

As a result, if the vehicle is suddenly decelerated, overcharging may be caused. However, the gradual operation does not cause overcharging and does not give a feeling of discomfort to the occupant.

Further, an accelerator lever (accelerator volume 6) for instructing traveling in the forward or reverse direction is provided.
And the deceleration means is configured to return to the vehicle speed before the deceleration when the accelerator lever is turned on after being turned off.

Thus, without giving a feeling of strangeness,
The intention of the occupant can be reflected.

[0075]

According to the first aspect of the present invention, the vehicle includes an electric motor that is driven by a battery mounted on the vehicle and drives the wheels. The electric motor is driven and controlled in accordance with an occupant's instruction to travel in the forward or reverse direction. In a small vehicle that charges the vehicle-mounted battery while decelerating the traveling speed by regenerative braking during deceleration such as when going downhill, it is possible to prevent the vehicle-mounted battery from being overcharged when going downhill. In addition, since it is sufficient to reduce the traveling speed and there is no need to stop the traveling of the vehicle, it is convenient for the occupants and does not cause any trouble even in the case of emergency slamming.

According to the second aspect of the present invention, overcharging may be caused instead. However, overcharging is not caused by performing the operation gradually, and the passenger does not feel uncomfortable.

According to the third aspect, the intention of the occupant can be reflected without giving a feeling of strangeness.

[Brief description of the drawings]

FIG. 1 is a plan view showing an entire configuration of a small electric vehicle according to the present invention.

FIG. 2 is a reduced side view of the small electric vehicle shown in FIG.

FIG. 3 is a front view of the small electric vehicle shown in FIG.

FIG. 4 is a rear view of the small electric vehicle shown in FIG. 1;

FIG. 5 is a block diagram specifically showing a configuration of a control unit of the small electric vehicle in FIG.

FIG. 6 is a circuit diagram showing details of a motor drive circuit incorporated in the control unit of FIG. 5;

FIG. 7 is an enlarged plan view of a main control panel of the small electric vehicle in FIG. 1;

FIG. 8 is an explanatory diagram of the main control panel shown in FIG. 7;

9 is an explanatory graph showing an output voltage characteristic of a speed volume of the main control panel shown in FIG. 7;

FIG. 10 is an explanatory graph showing an output voltage characteristic of an accelerator volume of the main control panel shown in FIG. 7;

11 is a flowchart showing the operation of the small electric vehicle shown in FIG.
It is a chart.

FIG. 12 is an explanatory diagram of a battery voltage for explaining the operation of the flowchart of FIG. 11;

[Explanation of symbols]

 Reference Signs List 10 small electric vehicle 28 electric motor 38 battery (vehicle-mounted battery) 50 control unit (electronic control unit) 62 key switch (power switch) 68 accelerator volume (accelerator lever) 74 indicator

Claims (3)

[Claims] An electric motor which is energized by an on-vehicle battery to drive the wheels, drives the electric motor in accordance with an occupant's instruction, travels in a forward direction or a reverse direction, and uses a regenerative brake when descending a hill. In a small electric vehicle for charging a battery, a. Battery voltage detecting means for detecting the voltage of the vehicle-mounted battery; b. Battery voltage determining means for determining whether or not the detected battery voltage exceeds a first predetermined value; c. A small electric vehicle comprising: a deceleration unit that reduces a traveling speed when it is determined that the detected battery voltage exceeds the first predetermined value. 2. The small electric vehicle according to claim 1, wherein said speed reduction means reduces said traveling speed at predetermined time intervals. 3. The method of claim 2, further comprising: d. 2. The vehicle according to claim 1, further comprising: an accelerator lever for instructing the vehicle to travel in a forward direction or a reverse direction, and wherein the deceleration means returns to the vehicle speed before the deceleration when the accelerator lever is turned on after being turned off. Item 3. The small electric vehicle according to item 2.