Electricity: motive power systems – Limitation of motor load – current – torque or force
Reexamination Certificate
1999-09-28
2001-06-12
Martin, David S. (Department: 2837)
Electricity: motive power systems
Limitation of motor load, current, torque or force
C180S065800, C360S093000
Reexamination Certificate
active
06246198
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a current-limiting value setting method for an electric-vehicle traveling motor, and a device for practicing the method.
2. Description of the Related Art
Heretofore, in an industrial or electric-vehicle motor, a current-limiting value setting operation is carried out; more specifically, an adjusting operation comprised of setting a predetermined upper-limit current with respect to a rated current, which flows at the time of motor lock, is carried out. The current-limiting value is a value which is suitable for the actual application of the user or the design of the motor, and therefore it is determined for every user.
An arrangement and method for setting the current limit value will be described with reference to FIG.
3
. The current flowing in the motor is chopper-controlled by a control element
1
which is connected in series to the armature A of the motor. The control element
1
is controlled by a control board (substrate)
2
including, among other things a micro-computer. The control board
2
is to chopper-control the motor current with a predetermined duty-cycle according to a motor current value detected by a current sensor CT and an instruction value provided by the accelerator (not shown). This current-value setting operation of the motor current is carried out as follows: With the motor locked and with the accelerator operated fully, the effective current of the motor is measured with a current meter
3
(provided separately). And a current-limiting value adjusting resistor (a variable resistor) VR in the control board
2
is adjusted such that the motor current value is equal to a predetermined current-limiting value.
However, the above-described conventional current-limiting value adjusting method and corresponding device suffer from the following problems: It is necessary to separately provide the current meter
3
, and the accelerator operation section and the control board
2
are spaced apart from each other. Hence, it is necessary to provide two operators, a person for performing the accelerator operation for the motor current, and a person for adjusting the variable resistor VR in the control board
2
. That is, the method and device are low in work efficiency.
SUMMARY OF THE INVENTION
Accordingly, an object of the invention is to solve the above-described problems. More specifically, an object of the invention is to provide a current-limiting value setting method for an electric-vehicle motor in which the current-limiting adjustment is simple and can be achieved by a single person, and it is unnecessary to additionally provide a current meter, and which has a high work efficiency, and a device for practicing the method.
The foregoing object of the invention has been achieved by the provision of the following means:
(1) A first embodiment of the invention includes a current-limiting value setting method in which a control circuit of an electric vehicle motor is adjusted, to set a predetermined upper current corresponding to a rated current which flows when the motor is locked.
The method comprises placing the mode of the control circuit in a current-limiting value setting mode, and with the motor locked, displaying a detection current value of the motor on a display means.
Further, an adjustment means is operated up and/or down and with an accelerator adapted to issue a traveling instruction operated fully, the adjusted means increases or decreases a duty-cycle of the application of the current to the motor so that the detection current value displayed on the display means is a predetermined current-limiting value.
Also, in accordance with this embodiment, when the detection current value reaches the predetermined current limiting value, the duty-cycle of the current at that time is stored in memory means, and the mode of the control circuit is switched back to an effective current display mode.
In accordance with the method, in the current-limiting value setting mode, the motor is locked, and with the accelerator operated fully the detection current value of the motor, which has been originally provided for controlling the motor traveling operation is displayed on the display means, and the operator, while observing the display, operates the up/down adjusting means so that the detection current value displayed on the display is the predetermined current value. When the detection current value reaches the predetermined current-limiting value, the duty-cycle of the current is stored in the memory means, and the mode is switched back to the effective current display mode. And, when necessary, with the motor maintained in a locked state, it is confirmed that the effective current value is the preset current-limiting value. Hence, it is unnecessary to additionally provide the current meter, and it is possible for a single person to achieve the adjusting operation.
(2) A second embodiment of the invention includes a current-limiting value setting device in which a control circuit of an electric vehicle motor is adjusted, to set a predetermined upper current corresponding to a rated current which flows when the motor is locked.
A device in accordance with the second embodiment of the invention comprises a
mode switching means for switching a mode of the control circuit over to a current-limiting value setting mode;
displaying means for displaying a detection current value of the motor with the motor locked;
an accelerator which is provided at a driver's seat, and issues a traveling instruction;
up/down adjusting means which is provided near the driver's seat, and increases or decreases a duty of application of current to the motor; and
memory means for storing a duty-cycle of the current when the detection current value reaches a predetermined current limiting value, and
in which when a mode of the control circuit is set to a current-limiting value setting mode, with the accelerator operated fully the up/down adjusting means is operated so that a detection current value displayed on the display means is a predetermined current-limiting value, and the duty-cycle of the current at that time is stored in the memory means.
The second embodiment has similar results as the first embodiment.
REFERENCES:
patent: 3855512 (1974-12-01), Konrad
patent: 4172232 (1979-10-01), Joyes
patent: 4514665 (1985-04-01), Meloak et al.
patent: 4772829 (1988-09-01), Pickering et al.
patent: 5341077 (1994-08-01), Chen et al.
patent: 5568052 (1996-10-01), Swaq-Tin et al.
patent: 5736831 (1998-04-01), Harrington
patent: 5934398 (1999-08-01), Hotta
patent: 56-68294 (1981-06-01), None
Banba Tadashi
Makino Noriaki
Martin David S.
Nippon Yusoki Co., Ltd.
Sughrue Mion Zinn Macpeak & Seas, PLLC
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