Differential drive system

Abstract

The differential drive system uses components produced on a large scale to produce operations similar to multi-speed, automatic transmissions while still utilizing the advantages of scale economy. A differential drive system couples two motors to a differential through flywheels to achieve most efficient motor usage. The pedal sprocket is connected to the differential through the intermediate shaft and the flywheel to allow the pedal to drive the two rear shafts.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. Provisional Patent Application Serial No. 63 / 388,348 filed on July 12, 2022 and U.S. Patent Application Serial No. 18 / 220,011 filed on July 10, 2023, the entire contents of both applications are incorporated herein by reference. Technical Field

[0003] The present invention relates to electric vehicle drive systems and, in particular, to improved drive systems that benefit from simplicity and economies of scale. Background Art

[0004] Known drive systems for three-wheeled and four-wheeled electric vehicles have the benefits of simplicity and economies of scale due to mass production. Unfortunately, many known drive systems require expensive transmissions to provide starting torque and sufficient speed. Known systems are also only able to couple the rider's pedals to one axle and require external components for vehicle speed sensing and pedal speed measurement. Summary of the invention

[0005] The present invention solves the above and other needs by providing a differential drive system that uses mass-produced components to produce operation similar to a multi-speed, automatic transmission while still taking advantage of economies of scale. The differential drive system couples two motors to the differential through a flywheel to achieve the most efficient motor usage. A pedal sprocket is connected to the differential through an intermediate shaft and a flywheel to allow the pedals to drive both rear axles.

[0006] According to one aspect of the present invention, a differential drive system is provided that does not require the addition of external components for speed sensing and pedal input. Magnets may be attached to gears in the differential drive system and to a Hall Effect sensor attached inside the differential drive system.

[0007] According to another aspect of the invention, a differential drive system is provided having a simple, robust and compact gear arrangement and a maintenance-free housing for the differential and motor on a heavy cargo tricycle. An intermediate shaft carries a gear that engages with the motor gear and the differential gear. The gear ratio can be changed by changing the gear carried by the intermediate shaft. The motors are identical, thereby reducing component inventory.

[0008] According to yet another aspect of the invention, there is provided a differential drive system comprising a pedal sprocket coupled to a differential via a flywheel. The pedal sprocket engages one of the intermediate shafts, which benefits from the reduced rotational speed of the intermediate shaft compared to the motor speed. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The above and other aspects, features and advantages of the present invention will become more apparent from the following more detailed description of the present invention set forth in conjunction with the following drawings, in which:

[0010] Figure 1 A dual-motor differential drive system according to the present invention is shown.

[0011] Figure 2 A vehicle including a dual-motor differential drive system according to the present invention is shown.

[0012] Figure 3 An exploded view of a dual-motor differential drive system according to the present invention is shown.

[0013] Figure 4 A top view of the motors and gears of the dual-motor differential drive system according to the present invention is shown.

[0014] Figure 5 A top front view of the motors and gears of a dual-motor differential drive system according to the present invention is shown.

[0015] Figure 6 A top rear view of the motors and gears of the dual-motor differential drive system according to the present invention is shown.

[0016] Figure 7 A differential gear including magnets for a Hall Effect speed sensor is shown.

[0017] Figure 8 A differential gear including magnets and a Hall Effect speed sensor is shown.

[0018] Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings. DETAILED DESCRIPTION

[0019] The following description is the best mode currently conceived for implementing the present invention. This description should not be understood as limiting, but is made only for the purpose of describing one or more preferred embodiments of the present invention. The scope of the present invention should be determined with reference to the claims.

[0020] Where the term "about" or "approximately" is used in connection with elements of the invention, it is intended to describe the appearance of a feature as perceived by the human eye or human rather than an exact measurement or typically within 10% of a stated value. For example, approximately 30 teeth may be between 27 teeth and 33 teeth.

[0021] Several elements are labeled "a" and "b". These elements may also be referred to as right and left. The terms right and left are not intended to be limiting, and the components may be rotated between the horizontal to vertical views in the drawings without departing from the invention.

[0022] exist Figure 1 1 shows a dual motor differential drive system 10 according to the present invention. The dual motor differential drive system 10 includes motors 12a and 12b attached to a two-piece housing 16. The pedal input sprocket 14 is connected to an intermediate shaft 28a or 28b in the housing 16a, 16b (see Figure 3 ), preferably connected to an intermediate shaft 28a or 28b in the housing 16a, 16b via a flywheel 15 (see Figure 3 ).

[0023] Figure 2 , a vehicle 50 including a dual motor differential drive system 10 is shown. Axle 54 and right and left tires 56a and 56b are driven by the dual motor differential drive system 10. Pedals 60 are positioned in front of the seat 52 and are connected to the sprocket 14 via a chain 58.

[0024] Figure 3 1 shows an exploded view of a dual motor differential drive system 10. The dual motor differential drive system 10 includes motors 12a and 12b attached to a housing side 16b of a housing 16 and motor gears 18a and 18b on motor shafts 20 extending into the housing side 16b. The ends of the motor shafts 20 are supported by bearings 22 fixed to the housing side 16a.

[0025] A first intermediate shaft 28a is supported by intermediate shaft bearings 26 fixed to the housing sides 16a and 16b and extends out of the first housing side 16a. A second intermediate shaft 28b is located between the housing sides 16a and 16b and is supported by intermediate shaft bearings 26 fixed to the housing sides 16a and 16b. Motor intermediate shaft gears 24a and 24b are located on intermediate shafts 28a and 28b and engage respective motor gears 18a and 18b. Differential intermediate shaft gears 30a and 30b are located on intermediate shafts 28a and 28b and engage differential gears 34 on a differential 32 supported by bearings 36.

[0026] The motor intermediate shaft gears 24a and 24b or the differential intermediate shaft gears 30a and 30b may be engaged with their respective intermediate shafts 28a and 28b using an intermediate shaft flywheel 31 (e.g., an overrunning clutch or overrunning clutch), or the motor gears 18a and 18b may be engaged with the motor shaft 20 via a flywheel. The flywheel 31 disengages the corresponding motor 12a or 12b from the differential 32, and then the corresponding motor 12a or 12b does not drive the differential 32. The flywheel 31 preferably couples the motor intermediate shaft gears 24a and 24b to the intermediate shafts 28a and 28b, allowing more space for the flywheel since the motor intermediate shaft gears 24a and 24b are generally larger in diameter relative to the differential intermediate shaft gears 30a and 30b.

[0027] The pedal sprocket 14 is preferably coupled to one of the intermediate shafts 28a or 28b via a flywheel 15 .

[0028] The motor gears 18a and 18b preferably have the same number of teeth, and more preferably have 16 teeth. The motor intermediate shaft gears 24a, 24b preferably have about 70 teeth, and more preferably have 70 teeth. The differential intermediate shaft gear 30 preferably has about 23 teeth, and preferably has 23 teeth. The differential gear 34 preferably has about 72 teeth, and more preferably has 72 teeth. The housings 16a and 16b are configured to position the motor shaft 20 and the intermediate shafts 28a and 28b separately to provide proper engagement of the motor gear 18 and the first intermediate shaft gears 24a and 24b. The number of teeth on the first intermediate shaft gears 24a and 24b can be varied according to the application to change the overall gear ratio, and a person skilled in the art can select a low gear ratio for a heavy vehicle and a high gear ratio for a light vehicle. The dual motor differential drive system 10 preferably has an overall gear ratio of about 13.7 to 1.

[0029] Figure 4 FIG. 1 shows a top view of the motors 12a and 12b and the gears of the dual-motor differential drive system 10, Figure 5 A top front view of the motors 12a and 12b and gears of the dual motor differential drive system is shown in FIG. Figure 6 1 shows a top rear view of the motors 12a and 12b and gears of the dual motor differential drive system.

[0030] Figure 7 The differential gear 34 including a magnet 40 for a Hall effect speed sensor 42 is shown in FIG. Figure 8 1 and 2 are shown with the Hall Effect speed sensor 42 and differential gear 34 attached to housing 16a. Magnet 40 may alternatively be located on any of the gears in differential drive system 10.

[0031] Industrial Applicability

[0032] The present invention has industrial applicability in the field of electric vehicles.

[0033] Scope of the Invention

[0034] Although the invention disclosed herein has been described by means of specific embodiments and applications of the invention, numerous modifications and variations may be made to the invention by those skilled in the art without departing from the scope of the invention as set forth in the claims.

Claims

1. An electric vehicle including a differential drive system, the vehicle comprising: at least three wheels, the at least three wheels comprising a right wheel and a left wheel; The right wheel and the left wheel are connected to a differential drive system via a right shaft and a left shaft; The differential drive system comprises: A housing, the housing comprising a right housing and a left housing; a differential, the differential being located inside the housing; a differential gear attached to the differential; the right shaft and the left shaft, the right shaft and the left shaft being connected to the differential; at least two motors, the motors attached to the housing; a motor shaft for each motor, the motor shaft extending into the housing; a motor gear, the motor gear being located on the motor shaft and being located inside the housing; two intermediate shafts, the intermediate shafts being located inside the housing; a motor intermediate shaft gear mounted on the intermediate shaft and engaging the motor gear; a differential countershaft gear mounted on the countershaft and engaging the differential gear; and A flywheel mechanically and rotationally couples the motor shaft to the differential when the corresponding motor drives the differential.

2. The vehicle according to claim 1, wherein: The differential drive system includes a pedal sprocket, which is rotationally attached to one of the motor shafts, one of the intermediate shafts or the differential through a sprocket flywheel. When the pedal sprocket does not drive the corresponding one of the motor shafts, the intermediate shafts or the differential, the sprocket is disengaged from one of the motor shafts, one of the intermediate shafts or the differential.

3. The vehicle according to claim 3, wherein: The pedal sprocket is rotationally coupled to one of the intermediate shafts.

4. The vehicle according to claim 3, wherein: The pedal sprocket is rotationally coupled to one of the intermediate shafts through a flywheel when the pedal sprocket drives a corresponding one of the intermediate shafts.

5. The vehicle according to claim 1, wherein: The flywheel rotationally couples the countershaft to one of the motor countershaft gear and the differential countershaft gear.

6. The vehicle according to claim 5, wherein: The flywheel rotationally couples the intermediate shaft and the motor intermediate shaft gear.

7. The vehicle according to claim 1, wherein: The motor, motor shaft and motor gear are removable and replaceable without separating the right housing from the left housing.

8. The vehicle of claim 1, wherein: The motors, motor shafts and motor gears are interchangeable.

9. The vehicle of claim 1, wherein: The gear ratio of the differential drive system can be changed by replacing the motor intermediate shaft gears.

10. The vehicle of claim 1, wherein: The motor gear has approximately 16 teeth and the motor intermediate shaft gear has approximately 70 teeth.

11. The vehicle according to claim 10, wherein: The differential countershaft gear has approximately 23 teeth, and the differential gear has approximately 72 teeth.

12. The vehicle of claim 1, wherein: The differential drive system comprises: a magnet attached to at least one of the differential, a first motor countershaft gear, the differential countershaft gear, and the motor gear; and A Hall effect sensor is attached to the interior of the housing and magnetically cooperates with the magnet.

13. The vehicle of claim 12, wherein: The magnets are attached to the differential.

14. An electric vehicle including a differential drive system, the vehicle comprising: at least three wheels, the at least three wheels comprising a right wheel and a left wheel; The right wheel and the left wheel are connected to the differential drive system via a right shaft and a left shaft; The differential drive system comprises: A housing, the housing comprising a right housing and a left housing; a differential, the differential being located inside the housing; a differential gear attached to the differential; the right shaft and the left shaft, the right shaft and the left shaft being connected to the differential; at least two motors, the motors attached to the housing; a motor shaft for each motor, the motor shaft extending into the housing; a motor gear, the motor gear being located on the motor shaft and being located inside the housing; two intermediate shafts, the intermediate shafts being located inside the housing; a motor intermediate shaft gear mounted on the intermediate shaft and engaging the motor gear; a differential countershaft gear mounted on the countershaft and engaging the differential gear; and A flywheel mechanically and rotationally couples the motor countershaft gear to the countershaft when the corresponding motor drives the differential.

15. An electric vehicle including a differential drive system, the vehicle comprising: at least three wheels, the at least three wheels comprising a right wheel and a left wheel; The right wheel and the left wheel are connected to the differential drive system via a right shaft and a left shaft; The differential drive system comprises: A housing, the housing comprising a right housing and a left housing; a differential, the differential being located inside the housing; a differential gear attached to the differential; the right shaft and the left shaft, the right shaft and the left shaft being connected to the differential; at least two motors, the motors attached to the housing; a motor shaft for each motor, the motor shaft extending into the housing; a motor gear, the motor gear being located on the motor shaft and being located inside the housing; two intermediate shafts, the intermediate shafts being located inside the housing; a motor intermediate shaft gear mounted on the intermediate shaft and engaging the motor gear; a differential countershaft gear mounted on the countershaft and engaging the differential gear; a flywheel that rotationally mechanically couples the motor countershaft gear to the countershaft when the corresponding motor drives the differential; and A pedal sprocket is rotationally mechanically coupled to one of the intermediate shafts via a flywheel when the pedal sprocket drives a corresponding one of the intermediate shafts.

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