US3885204A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Drive arrangement using electric motor with variable hydraulic transmission set in predetermined relationship to minimize battery drain
Assignee: Linde GmbH
•
Filing: 1973-04-26
•
Granted: 1975-05-20
•
Expires: 1993-04-26
Abstract
Abstract A drive system using a shunt-wound electric motor, especially for fork-lift vehicles and the like, comprises a variable hydrostatic transmission connected between the shunt-wound electric motor and the wheels of the vehicle and provides means for varying the excitation current of the field winding of the electric motor.
Inventors
- 👤 Theodore Abels
- 👤 Siegfried Puschel
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 03:35
CPC Classifications
B; B60; B60L; B60L50/00; B60L50/50; B60L50/52; Y; Y02; Y02T; Y02T10/00; Y02T10/60; Y02T10/64; Y02T10/70
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
126 words
A drive system comprising, in combination a storage battery; a shunt-wound electric motor having a field-excitation coil connected in shunt with an armature across said battery; a stepless variable hydraulic transmission including a hydraulic pump drivingly connected to said electric motor and a hydraulic motor operatively cOnnected to a load and in fluid communication with said pump; and control means for varying the excitation current of said field coil, said transmission comprising a transmission control element for varying the speed ratio between said pump and said hydraulic motor, said control means for varying the current through said field coil including a currentcontrol element for joint and simultaneous regulation of the current through said field coil and said ratio in a predetermined relationship to minimize battery drain.
Claim 2
Dependent Claim
126 words
A drive system comprising, in combination a storage battery; a shunt-wound electric motor having a field-excitation coil connected in shunt with an armature across said battery; a stepless variable hydraulic transmission including a hydraulic pump drivingly connected to said electric motor and a hydraulic motor operatively cOnnected to a load and in fluid communication with said pump; and control means for varying the excitation current of said field coil, said transmission comprising a transmission control element for varying the speed ratio between said pump and said hydraulic motor, said control means for varying the current through said field coil including a currentcontrol element for joint and simultaneous regulation of the current through said field coil and said ratio in a predetermined relationship to minimize battery drain.
Claim 3
Dependent Claim
38 words
The drive system defined in claim 1 for a vehicle wherein said transmission is connected to the driving wheels thereof and said vehicle has a drive-control element operatively connected to said transmission-control element and to said current-control element.
Claim 4
Dependent Claim
32 words
The drive system defined in claim 2 wherein said electric motor is a pure shunt-wound motor having no excitation coil apart from the aforementioned field coil connected in shunt with said armature.
Claim 5
Dependent Claim
35 words
The drive system defined in claim 2 wherein said drive-control element is a pedal operatively connected to said current-control element for increasing the excitation field with reduction in the output speed of said hydraulic motor.
Claim 6
Dependent Claim
59 words
The drive system defined in claim 4 wherein said vehicle is provided with a hydraulic lifting mechanism having a pump connected to said shunt-wound electric motor and a lifting-control element for regulating the supply of fluid to said mechanism, said lifting-control element being operatively connected to said current-control element for increasing the excitation field upon lowering of said mechanism.
Claim 7
Dependent Claim
29 words
The drive system defined in claim 1 wherein said elements are so connected and arranged that with decreasing output speed of said electric motor, the excitation field is increased.
Claim 8
Dependent Claim
50 words
The drive system defined in claim 1 wherein said transmission is a hydraulic lifting mechanism provided with a lifting-control element, said means for controlling said current including a current-control element operatively connected to said lifting control element for increasing the excitation field of said coil upon lowering of said mechanism.
Claim 9
Dependent Claim
52 words
The drive system defined in claim 1 wherein said means for controlling said current includes a variable resistance network in series with said coil and a current-control element for varying the resistance of said network, said transmission being provided with a control element operatively connected to said control element of said network.
Claim 10
Dependent Claim
32 words
The drive system defined in claim 8 wherein said network is a variable resistor having a wiper and said control element of said transmission is a lever operatively connected to said wiper.
Claim 11
Dependent Claim
27 words
The drive system defined in claim 8 wherein said network is the collector-emitter network of a transistor and said current-control element includes means for biasing said transistor.
Claim 12
Dependent Claim
42 words
The drive system defined in claim 8 wherein said network includes a resistor of substantially fixed resistance connected in series with said coil, a transistor having a collector-emitter network bridged across said resistor, and means for controlling the bias on said transistor.
Claim 13
Dependent Claim
21 words
The drive system defined in claim 11, further comprising a diode bridged across said coil in series with said collector-emitter network.
Claim 14
Dependent Claim
29 words
The drive system defined in claim 8 wherein said network includes a plurality of resistors and switch means selectively connecting one of said resistors in series with said coil.
Claim 15
Dependent Claim
34 words
The drive system defined in claim 8 wherein said network includes a further field coil connectable in series with the first-mentioned field coil, said field coils together forming sections of a tapped field coil.
Claim 16
Dependent Claim
35 words
The drive system defined in claim 14 wherein said network further comprises a transistor having its collector-emitter network connected in shunt across one of said sections, and means for controlling the bias on said transistor.
Claim 17
Dependent Claim
18 words
The drive system defined in claim 8, further compRising a transistor amplifier between said element and said network.
Claim 18
Dependent Claim
61 words
The drive system defined in claim 1 for a fork-lift vehicle wherein said hydraulic motor is connected to a driving wheel of the vehicle, further comprising a switch in circuit with said electric motor and operatively connected to said transmission-control element for electrically disconnecting said electric motor upon movement of said transmission-control element into a neutral position of said hydraulic transmission.
Claim 19
Dependent Claim
43 words
The drive system defined in claim 17, further comprising a time-delay device interposed between said transmission control element and said switch for operating said switch only upon the disposition of said transmission control element into the neutral position for a predetermined time period.
Claim 20
Dependent Claim
30 words
The drive system defined in claim 1 wherein said hydraulic transmission is a hydrostatic transmission, said hydraulic pump is an axial-piston pump and said hydraulic motor is an axial-piston motor.
Claim 21
Dependent Claim
79 words
The drive system defined in claim 1 for a vehicle having a pair of driven wheels on opposite sides thereof, said transmission including a respective hydraulic motor drivingly connected to each of said wheels, said vehicle being further provided with a steering linkage, said drive system further comprising a valve between said pump and each of said hydraulic motors for distributing fluid between them in response to operation of said steering linkage to permit differential rotation of said wheels.
Claim 22
Dependent Claim
87 words
The drive system defined in claim 1 for a fork-lift vehicle having driven wheels connected to said hydraulic motor, a further hydraulic pump connected to said electric motor, a hydraulic lifting mechanism communicating with said further pump, a lift-control lever for regulating the flow of fluid from said further pump to said mechanism, and a switch in circuit with said battery and said electric motor and operatively connected to said lever for open-circuiting said switch upon displacement of said lever into an ''''off'''' position of said mechanism.
Claim 23
Dependent Claim
38 words
The drive system defined in claim 21, further comprising a time-delay device between said switch and said lever for open-circuiting said switch only after a predetermined period subsequent to the disposition of said lever in said off position.
References Cited (Backward Citations)
US3280397A
Cited
US3457487A
Cited
US3424260A
Cited
US3529230A
Cited
US3512072A
Cited
US3593086A
Cited
US3659672A
Cited
US3686549A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-05-19 | 1978-11-18 | 1979-05-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-05-19 | 1982-11-18 | 1983-05-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-05-19 | 1986-11-18 | 1987-05-20 | $7700.00 | Window Closed / Lapsed |