CA2185474A1 - Top speed adjustment system for a dc series field motor - Google Patents
Top speed adjustment system for a dc series field motorInfo
- Publication number
- CA2185474A1 CA2185474A1 CA002185474A CA2185474A CA2185474A1 CA 2185474 A1 CA2185474 A1 CA 2185474A1 CA 002185474 A CA002185474 A CA 002185474A CA 2185474 A CA2185474 A CA 2185474A CA 2185474 A1 CA2185474 A1 CA 2185474A1
- Authority
- CA
- Canada
- Prior art keywords
- motor
- series
- variable resistor
- coupled
- field
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P7/00—Arrangements for regulating or controlling the speed or torque of electric DC motors
- H02P7/06—Arrangements for regulating or controlling the speed or torque of electric DC motors for regulating or controlling an individual dc dynamo-electric motor by varying field or armature current
- H02P7/08—Arrangements for regulating or controlling the speed or torque of electric DC motors for regulating or controlling an individual dc dynamo-electric motor by varying field or armature current by manual control without auxiliary power
- H02P7/10—Arrangements for regulating or controlling the speed or torque of electric DC motors for regulating or controlling an individual dc dynamo-electric motor by varying field or armature current by manual control without auxiliary power of motor field only
Abstract
A DC series field motor with a top speed adjustment system in accordance with the present invention includes a motor field coil, a motor armature, a power supply, and a variable resistor. The motor field coil and the motor armature arecoupled in series to the power supply and a variable resistor is coupled in parallel with the motor field coil. The motor armature rotates at a first speed in response to the first strength of the magnetic field generated by the motor field coil. When the resistance of the variable resistor is adjusted, the first strength of the first magnetic field is adjusted to a second strength and the motor armature rotates at a second speed in response to the second strength.
Description
TOP SPEED ADJUSTMENT SYSTEM FOR A
D.C. SERIES FIELD MOTOR
FIELD OF THE INVENTION
This invention relates generally to speed adjustment system and more particularly to a system for adjusting a top speed of an electric industrial vehicle with a DC series field motor and an open loop speed control system to an upper limit.
BACKGROUND OF THE INVENTION
A problem in the manufacture of electric industrial vehicles with open loop speed control systems is that the top speed of different electric industrial vehicles which are the same model type can vary. Controlling the top speed of the electric industrial vehicle is important for both safety and marketing reasons. If the top speed of an electric industrial vehicle is too high (e.g. above the top recommend speed for the lift truck), then the electric industrial vehicle may tip over when the vehicle reaches the top speed. Additionally, consumers prefer to have a consistent top speed for the same model of electric industrial vehicle. Moreover, government regulations often require that the speed of certain electric industrial vehicles not exceed a top set speed.
SUMMARY OF INVENTION
In accordance with one aspect of the present invention there is provided a DC series field motor with a top speed adjustment system comprising: a motor field coil which generates a magnetic field having a strength, the coil having first and second terminals; a motor armature coupled in series with said motor field coil, wherein said motor field coil and said motor armature are coupled in series to a power supply, said motor armature rotating at a speed in response to said strength for said magnetic field; and an adjustable variable resistor capable of providing any resistance value within a range of resistances for adjusting the strength of said magnetic field, said variable resistor for adjusting coupled across the first and second terminals in parallel with said motor field coil, said motor armature speed dependent on the magnetic field strength.
In accordance with another aspect of the present invention there is provided an electric industrial vehicle with a top speed adjustment system comprising:
a motor field coil generating a magnetic field having a strength, the coil having first and second terminals; a motor armature coupled in series with said motor field coil, wherein said motor field coil and said motor armature are coupled in series to a power supply; a drive shaft for the electric industrial vehicle coupled to said motor armature, said motor armature rotating said drive shaft as a speed in response to said strength of said magnetic field; and an adjustable variable resistor capable of providing any resistance value within a range of resistances coupled across the first and second terminals in parallel with said motor field coil, said variable resistor adjusting said strength of said magnetic field and said motor armature rotating said drive shaft at a speed in response to said strength for said magnetic field.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a circuit diagram of a top speed adjustment system for an electric industrial vehicle with a DC series field motor in accordance with the present invention; and FIG. 2 is an enlarged view of the variable resistor shown in FIG. 1.
- 2a -DETAILED DESCRIPTION
A top speed adjustment system 10 for an electric industrial vehicle 12 with a DC series field motor in accordance with the present invention is illustrated in FIG. 1. Electric industrial vehicle 12 includes a motor field coil 14, a motor armature 16, a variable resistor 18, and a battery 20. With system 10, every electric industrial vehicle 12 of a particular model can be easily adjusted to have the same upper limit for the top speed.
Referring more specifically to FIG. 1, motor 11 comprises motor field coil 14 and motor armature 16. One terminal from motor field coil 14 is coupled in series to one terminal of motor armature 16. The other terminal of motor armature 16 is coupled in series to one terminal of a motor controller 22. The other terminal of motor controller 22 is coupled to ground and to a negative terminal for battery 20.
Motor controller 22 is part of an open loop speed control system (not shown) in electric industrial vehicle 12. A positive terminal for 2185474.
D.C. SERIES FIELD MOTOR
FIELD OF THE INVENTION
This invention relates generally to speed adjustment system and more particularly to a system for adjusting a top speed of an electric industrial vehicle with a DC series field motor and an open loop speed control system to an upper limit.
BACKGROUND OF THE INVENTION
A problem in the manufacture of electric industrial vehicles with open loop speed control systems is that the top speed of different electric industrial vehicles which are the same model type can vary. Controlling the top speed of the electric industrial vehicle is important for both safety and marketing reasons. If the top speed of an electric industrial vehicle is too high (e.g. above the top recommend speed for the lift truck), then the electric industrial vehicle may tip over when the vehicle reaches the top speed. Additionally, consumers prefer to have a consistent top speed for the same model of electric industrial vehicle. Moreover, government regulations often require that the speed of certain electric industrial vehicles not exceed a top set speed.
SUMMARY OF INVENTION
In accordance with one aspect of the present invention there is provided a DC series field motor with a top speed adjustment system comprising: a motor field coil which generates a magnetic field having a strength, the coil having first and second terminals; a motor armature coupled in series with said motor field coil, wherein said motor field coil and said motor armature are coupled in series to a power supply, said motor armature rotating at a speed in response to said strength for said magnetic field; and an adjustable variable resistor capable of providing any resistance value within a range of resistances for adjusting the strength of said magnetic field, said variable resistor for adjusting coupled across the first and second terminals in parallel with said motor field coil, said motor armature speed dependent on the magnetic field strength.
In accordance with another aspect of the present invention there is provided an electric industrial vehicle with a top speed adjustment system comprising:
a motor field coil generating a magnetic field having a strength, the coil having first and second terminals; a motor armature coupled in series with said motor field coil, wherein said motor field coil and said motor armature are coupled in series to a power supply; a drive shaft for the electric industrial vehicle coupled to said motor armature, said motor armature rotating said drive shaft as a speed in response to said strength of said magnetic field; and an adjustable variable resistor capable of providing any resistance value within a range of resistances coupled across the first and second terminals in parallel with said motor field coil, said variable resistor adjusting said strength of said magnetic field and said motor armature rotating said drive shaft at a speed in response to said strength for said magnetic field.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a circuit diagram of a top speed adjustment system for an electric industrial vehicle with a DC series field motor in accordance with the present invention; and FIG. 2 is an enlarged view of the variable resistor shown in FIG. 1.
- 2a -DETAILED DESCRIPTION
A top speed adjustment system 10 for an electric industrial vehicle 12 with a DC series field motor in accordance with the present invention is illustrated in FIG. 1. Electric industrial vehicle 12 includes a motor field coil 14, a motor armature 16, a variable resistor 18, and a battery 20. With system 10, every electric industrial vehicle 12 of a particular model can be easily adjusted to have the same upper limit for the top speed.
Referring more specifically to FIG. 1, motor 11 comprises motor field coil 14 and motor armature 16. One terminal from motor field coil 14 is coupled in series to one terminal of motor armature 16. The other terminal of motor armature 16 is coupled in series to one terminal of a motor controller 22. The other terminal of motor controller 22 is coupled to ground and to a negative terminal for battery 20.
Motor controller 22 is part of an open loop speed control system (not shown) in electric industrial vehicle 12. A positive terminal for 2185474.
battery 20 is coupled to the other terminal of motor field coil 14. Although a battery 20 is shown as the power source, other sources of power can be used if desired.
A drive shaft 24 for electric industrial vehicle 12 is coupled to motor armature 16. When motor 11 is turned on, motor armature 16 rotates drive shaft 24 to drive the wheels (not shown) of lift truck 12 in a manner well known in the art and thus not described in detail here. Motor armature 16 can rotate drive shaft 24 up to a top speed. Since electric industrial vehicle 12 has an open loop speed control system (not shown), the top speed between different electric industrial vehicles of the same model type can vary. With top speed adjustment system 10, the top speed for every electric industrial vehicle of the same model type can be set to substantially the same upper limit.
Top speed adjustment system 10 comprises a switch 26 and variable resistor 18. An enlarged view of variable resistor with terminals 21 and 23 is shown in FIG. 2. A solder bead 25 is located adjacent terminal 23 and sets the minimum resistance point for variable resistor 18. As shown in FIG. 1, switch is coupled in series with variable resistor 18 and both switch 26 and variable resistor 18 are coupled in parallel with motor field coil 14. Switch 26 is normally open and is closed if the speed of electric industrial vehicle 12 must be adjusted.
In this particular embodiment, variable resistor 18 has a resistance ranging from 6 milliohms to 12 milliohms, although the range of resistance can vary depending upon the particular application. As explained in greater detail below, the resistance of variable resistor 18 is adjusted to set or calibrate the top speed of electric industrial vehicle 12 to an upper limit.
When motor controller 22 is turned on, current from battery 20 flows through motor field coil 14, motor armature 16, and motor controller 22.
Current flowing through motor 11 generates a magnetic field which causes motor armature 16 to rotate. As the flow of current increases, the strength of the magnetic field increases until the motor 11 reaches top speed. This speed is dependent upon the load on motor 11. Motor controller 22 controls the flow current and thus the speed at which drive shaft 24 is rotated and electric industrial vehicle 12 moves. Since motor controller 22 is part of an open loop control system (not shown) in electric industrial vehicle 12, the top speed for electric industrial vehicle 12 will be different for each vehicle depending upon the vehicle's mechanical rolling resistance.
To further increase the speed of vehicle 12, switch 26 is closed to couple variable resistor 18 in parallel with motor field coil 14. Coupling variable resistor 18 in parallel with motor field coil 14 weakens the magnetic field of field coil 14 and thus increases the speed at which motor armature 16 rotates drive shaft 24. Again assuming a constant voltage and a constant load, increasing the resistance of variable resistor 18 increases the flow of current through motor field coil 14, thus increasing the magnetic field which reduces the speed at which motor armature 16 rotates drive shaft 24. Therefore, decreasing the resistance of variable resistor 18 decreases the flow of current through motor field coil 14, thus decreasing the magnetic field of the field coil 14 which increases the speed at which motor armature 16 rotates drive shaft 24.
To set the top speed of electric industrial vehicle 12 to an upper limit, top speed of electric industrial vehicle 12 is measured and compared against the upper limit. If there is a difference, then switch 26 is closed to couple variable resistor 18 in parallel with motor field coil 14. As discussed above, when variable resistor 18 is coupled in parallel with motor field coil 14 the magnetic field can be altered and thus the speed at which motor armature 16 rotates drive shaft 24 can be adjusted. Increasing the resistance of variable resistor 18 reduces the speed at which motor armature 16 rotates drive shaft 24 and decreasing the resistance of variable resistor 18 increases the speed at which motor armature 16 rotates drive shaft 24. Accordingly, the resistance of variable resistor 18 is adjusted and the speed of electric industrial vehicle 12 is measured until the top speed of electric 21854?4 industrial vehicle 12 substantially matches the set upper speed limit.
Adjusting the top speed by weakening the magnetic field of motor field coil 14 does result in a reduction in torque, but since a electric industrial vehicle 12 will only be allowed to reach the top speed at a light or no load condition, the reduction in torque to increase speed is an acceptable trade off. As described above, top speed adjustment system 10 is easy to install and is easy to use.
Having thus described the basic concept of the invention, it will be readily apparent to those skilled in the art that the foregoing detailed disclosure is intended to be presented by way of example only, and is not limiting. Various alterations, improvements, and modifications will occur and are intended to those skilled in the art, but not expressly stated herein. These modifications, alterations and improvements are intended to be suggested hereby, and within the spirit and scope of the invention. Accordingly, the invention is limited only by the following claims and equivalents thereto.
A drive shaft 24 for electric industrial vehicle 12 is coupled to motor armature 16. When motor 11 is turned on, motor armature 16 rotates drive shaft 24 to drive the wheels (not shown) of lift truck 12 in a manner well known in the art and thus not described in detail here. Motor armature 16 can rotate drive shaft 24 up to a top speed. Since electric industrial vehicle 12 has an open loop speed control system (not shown), the top speed between different electric industrial vehicles of the same model type can vary. With top speed adjustment system 10, the top speed for every electric industrial vehicle of the same model type can be set to substantially the same upper limit.
Top speed adjustment system 10 comprises a switch 26 and variable resistor 18. An enlarged view of variable resistor with terminals 21 and 23 is shown in FIG. 2. A solder bead 25 is located adjacent terminal 23 and sets the minimum resistance point for variable resistor 18. As shown in FIG. 1, switch is coupled in series with variable resistor 18 and both switch 26 and variable resistor 18 are coupled in parallel with motor field coil 14. Switch 26 is normally open and is closed if the speed of electric industrial vehicle 12 must be adjusted.
In this particular embodiment, variable resistor 18 has a resistance ranging from 6 milliohms to 12 milliohms, although the range of resistance can vary depending upon the particular application. As explained in greater detail below, the resistance of variable resistor 18 is adjusted to set or calibrate the top speed of electric industrial vehicle 12 to an upper limit.
When motor controller 22 is turned on, current from battery 20 flows through motor field coil 14, motor armature 16, and motor controller 22.
Current flowing through motor 11 generates a magnetic field which causes motor armature 16 to rotate. As the flow of current increases, the strength of the magnetic field increases until the motor 11 reaches top speed. This speed is dependent upon the load on motor 11. Motor controller 22 controls the flow current and thus the speed at which drive shaft 24 is rotated and electric industrial vehicle 12 moves. Since motor controller 22 is part of an open loop control system (not shown) in electric industrial vehicle 12, the top speed for electric industrial vehicle 12 will be different for each vehicle depending upon the vehicle's mechanical rolling resistance.
To further increase the speed of vehicle 12, switch 26 is closed to couple variable resistor 18 in parallel with motor field coil 14. Coupling variable resistor 18 in parallel with motor field coil 14 weakens the magnetic field of field coil 14 and thus increases the speed at which motor armature 16 rotates drive shaft 24. Again assuming a constant voltage and a constant load, increasing the resistance of variable resistor 18 increases the flow of current through motor field coil 14, thus increasing the magnetic field which reduces the speed at which motor armature 16 rotates drive shaft 24. Therefore, decreasing the resistance of variable resistor 18 decreases the flow of current through motor field coil 14, thus decreasing the magnetic field of the field coil 14 which increases the speed at which motor armature 16 rotates drive shaft 24.
To set the top speed of electric industrial vehicle 12 to an upper limit, top speed of electric industrial vehicle 12 is measured and compared against the upper limit. If there is a difference, then switch 26 is closed to couple variable resistor 18 in parallel with motor field coil 14. As discussed above, when variable resistor 18 is coupled in parallel with motor field coil 14 the magnetic field can be altered and thus the speed at which motor armature 16 rotates drive shaft 24 can be adjusted. Increasing the resistance of variable resistor 18 reduces the speed at which motor armature 16 rotates drive shaft 24 and decreasing the resistance of variable resistor 18 increases the speed at which motor armature 16 rotates drive shaft 24. Accordingly, the resistance of variable resistor 18 is adjusted and the speed of electric industrial vehicle 12 is measured until the top speed of electric 21854?4 industrial vehicle 12 substantially matches the set upper speed limit.
Adjusting the top speed by weakening the magnetic field of motor field coil 14 does result in a reduction in torque, but since a electric industrial vehicle 12 will only be allowed to reach the top speed at a light or no load condition, the reduction in torque to increase speed is an acceptable trade off. As described above, top speed adjustment system 10 is easy to install and is easy to use.
Having thus described the basic concept of the invention, it will be readily apparent to those skilled in the art that the foregoing detailed disclosure is intended to be presented by way of example only, and is not limiting. Various alterations, improvements, and modifications will occur and are intended to those skilled in the art, but not expressly stated herein. These modifications, alterations and improvements are intended to be suggested hereby, and within the spirit and scope of the invention. Accordingly, the invention is limited only by the following claims and equivalents thereto.
Claims (9)
1. A DC series field motor with a top speed adjustment system comprising:
a motor field coil which generates a magnetic field having a strength, the coil having first and second terminals;
a motor armature coupled in series with said motor field coil, wherein said motor field coil and said motor armature are coupled in series to a power supply, said motor armature rotating at a speed in response to said strength for said magnetic field; and an adjustable variable resistor capable of providing any resistance value within a range of resistances for adjusting the strength of said magnetic field, said variable resistor for adjusting coupled across the first and second terminals in parallel with said motor field coil, said motor armature speed dependent on the magnetic field strength.
a motor field coil which generates a magnetic field having a strength, the coil having first and second terminals;
a motor armature coupled in series with said motor field coil, wherein said motor field coil and said motor armature are coupled in series to a power supply, said motor armature rotating at a speed in response to said strength for said magnetic field; and an adjustable variable resistor capable of providing any resistance value within a range of resistances for adjusting the strength of said magnetic field, said variable resistor for adjusting coupled across the first and second terminals in parallel with said motor field coil, said motor armature speed dependent on the magnetic field strength.
2. The DC series field motor as set forth in Claim 1 wherein said means for adjusting is a variable resistor.
3. The DC series field motor as set forth in Claim 2 wherein the variable resistor has a resistance ranging from 6 milliohms to 12 milliohms.
4. The DC series field motor as set forth in Claim 2 further comprising a switch coupled in series with said variable resistor, said switch being normally open.
5. The DC series field motor as set forth in Claim 1 further comprising a motor controller coupled in series with said power supply, said motor field coil, and said motor armature.
6. An electric industrial vehicle with a top speed adjustment system comprising:
a motor field coil generating a magnetic field having a strength, the coil having first and second terminals;
a motor armature coupled in series with said motor field coil, wherein said motor field coil and said motor armature are coupled in series to a power supply;
a drive shaft for the electric industrial vehicle coupled to said motor armature, said motor armature rotating said drive shaft as a speed in response to said strength of said magnetic field; and an adjustable variable resistor capable of providing any resistance value within a range of resistances coupled across the first and second terminals in parallel with said motor field coil, said variable resistor adjusting said strength of said magnetic field and said motor armature rotating said drive shaft at a speed in response to said strength for said magnetic field.
a motor field coil generating a magnetic field having a strength, the coil having first and second terminals;
a motor armature coupled in series with said motor field coil, wherein said motor field coil and said motor armature are coupled in series to a power supply;
a drive shaft for the electric industrial vehicle coupled to said motor armature, said motor armature rotating said drive shaft as a speed in response to said strength of said magnetic field; and an adjustable variable resistor capable of providing any resistance value within a range of resistances coupled across the first and second terminals in parallel with said motor field coil, said variable resistor adjusting said strength of said magnetic field and said motor armature rotating said drive shaft at a speed in response to said strength for said magnetic field.
7. The electric industrial vehicle as set forth in Claim 6 wherein the variable resistor has a resistance ranging from 6 milliohms to 12 milliohms.
8. The electric industrial vehicle as set forth in Claim 6 further comprising a switch coupled in series with said variable resistor, said switch being normally open.
9. The electric industrial vehicle as set forth in Claim 6 further comprising a motor controller coupled in series with said power supply, said motor field coil, and said motor armature.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002185474A CA2185474A1 (en) | 1996-09-13 | 1996-09-13 | Top speed adjustment system for a dc series field motor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002185474A CA2185474A1 (en) | 1996-09-13 | 1996-09-13 | Top speed adjustment system for a dc series field motor |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2185474A1 true CA2185474A1 (en) | 1998-03-14 |
Family
ID=4158904
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002185474A Abandoned CA2185474A1 (en) | 1996-09-13 | 1996-09-13 | Top speed adjustment system for a dc series field motor |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2185474A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106644108A (en) * | 2017-01-24 | 2017-05-10 | 莱茵技术监督服务（广东）有限公司 | Adjustable load device for temperature rise test of agitator |
-
1996
- 1996-09-13 CA CA002185474A patent/CA2185474A1/en not_active Abandoned
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106644108A (en) * | 2017-01-24 | 2017-05-10 | 莱茵技术监督服务（广东）有限公司 | Adjustable load device for temperature rise test of agitator |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| FZDE | Dead |