Differential function electric drive assembly based on planet row

Abstract

The invention provides a differential function electric drive assembly based on a planet row. The differential function electric drive assembly based on the planet rows comprises a drive unit, a differential unit and two speed reduction units, the differential unit comprises a first-stage planet row and a second-stage planet row which are arranged side by side, and a planet carrier of the first-stage planet row is connected with a planet carrier of the second-stage planet row; a gear ring of the second-stage planet row is smaller than a gear ring of the first-stage planet row, a sun gear of the first-stage planet row is connected with the driving unit, a planet carrier of the second-stage planet row is connected with one speed reduction unit, and the gear ring of the first-stage planet row and the gear ring of the second-stage planet row are connected with the same gear shifting mechanism. And the gear shifting mechanism is connected with the other speed reduction unit. The problems that an existing bevel gear type differential mechanism is high in failure rate, and a planet row type differential mechanism is limited in application range are solved.

Description

Technical Field

[0001] This invention relates to electric drive systems, and more specifically to a differential electric drive assembly based on a planetary gear set. Background Technology

[0002] Forklift electric drive axle differentials typically use bevel gears and spur gears. Due to the slow speed of forklifts, difficulty in cooling the gearbox, poor oil lubrication, and high differential speeds, differential operation occurs frequently, making the differential prone to failure. To solve this problem, using a bevel gearless differential that still maintains differential torque capability can significantly reduce vehicle failures. One solution is to output the planetary carrier and ring gear of the planetary gear set to both sides, and connect them to reduction mechanisms to adjust to appropriate speed ratios, achieving differential torque capability. This method offers advantages such as small installation space, high energy density, and higher reliability, but it suffers from the drawback of difficult shifting mechanism placement. Typically, the shifting mechanism can only be placed at the input end, resulting in a bulky overall structure with large space requirements, low integration, and limited application range due to the inconvenience of adjusting the motor layout. Summary of the Invention

[0003] To address the issues of high failure rates in existing bevel gear differential mechanisms and limited application range of planetary gear differential mechanisms, this invention provides a planetary gear-based differential electric drive assembly that solves the aforementioned problems.

[0004] A differential electric drive assembly based on a planetary gear set includes a drive unit, a differential unit, and two reduction units. The differential unit includes a first-stage planetary gear set and a second-stage planetary gear set arranged side by side. The planet carrier of the first-stage planetary gear set is connected to the planet carrier of the second-stage planetary gear set. The ring gear of the second-stage planetary gear set is smaller than the ring gear of the first-stage planetary gear set. The sun gear of the first-stage planetary gear set is connected to the drive unit. The planet carrier of the second-stage planetary gear set is connected to one of the reduction units. The ring gears of the first-stage and second-stage planetary gear sets are connected to the same shift mechanism and are connected to the other reduction unit through the shift mechanism.

[0005] In a preferred embodiment of the differential electric drive assembly based on a planetary gear set provided by the present invention, the planet carrier of the secondary planetary gear set is provided with a first drive shaft, which passes through the secondary planetary gear set, the primary planetary gear set and the drive unit in sequence, and is connected to the reduction unit, referred to as the first reduction unit; the shifting mechanism is connected to a second drive shaft, which is connected to another reduction unit, referred to as the second reduction unit.

[0006] In a preferred embodiment of the differential electric drive assembly based on a planetary gear set provided by the present invention, the drive unit includes a motor, the shaft end of which is directly connected to the sun gear of the first-stage planetary gear set, and the first drive shaft passes sequentially through the second-stage planetary gear set, the first-stage planetary gear set, and the motor. The drive unit includes a motor and a transmission gear set, one or more of the motors are connected to the sun gear of the first-stage planetary gear set through the same transmission gear set, and the first drive shaft passes sequentially through the second-stage planetary gear set, the first-stage planetary gear set, and the transmission gear set.

[0007] In a preferred embodiment of the differential electric drive assembly based on planetary gear set provided by the present invention, the second drive shaft is a double-layer shaft, the gear ring of the second-stage planetary gear set is connected to the inner layer of the second drive shaft through the shifting mechanism, and the gear ring of the first-stage planetary gear set is connected to the outer layer of the second drive shaft through the shifting mechanism.

[0008] In a preferred embodiment of the differential electric drive assembly based on planetary gear set provided by the present invention, the shifting mechanism connects the gear ring of the second-stage planetary gear set with the inner layer of the second drive shaft, which is called first gear, or connects the gear ring of the first-stage planetary gear set with the outer layer of the second drive shaft, which is called second gear, or neither is connected, which is called neutral.

[0009] The shifting mechanism includes a first gear tooth, a second gear tooth, a sliding sleeve, and a control system. The first gear tooth is simultaneously located on the gear ring of the second-stage planetary gear set and the inner layer of the second drive shaft. The second gear tooth is simultaneously located on the gear ring of the first-stage planetary gear set and the outer layer of the second drive shaft. The control system moves the sliding sleeve to engage with the first gear tooth at two locations simultaneously to achieve first gear. Moving the sliding sleeve to engage with the second gear tooth at two locations simultaneously to achieve second gear. Moving the sliding sleeve to a position where it does not contact the first gear tooth or the second gear tooth simultaneously to achieve neutral gear.

[0010] In a preferred embodiment of the differential electric drive assembly based on a planetary gear set provided by the present invention, both the first reduction unit and the second reduction unit are planetary gear sets, with the first reduction unit having a ring gear output and the second reduction unit having a planet carrier output.

[0011] The second reduction unit includes a second-speed planetary gear set and a first-speed planetary gear set arranged side by side. The ring gears of the second-speed and first-speed planetary gear sets are fixed. The planet carrier of the second-speed planetary gear set is connected to the planet carrier of the first-speed planetary gear set and outputs from the planet carrier. The inner layer of the second drive shaft is connected to the sun gear of the first-speed planetary gear set, and the outer layer of the second drive shaft is connected to the sun gear of the second-speed planetary gear set.

[0012] Compared with existing technologies, the differential electric drive assembly based on planetary gear sets provided by this invention has the following beneficial effects: 1. The solution provided by the present invention uses a double planetary gear set as the differential unit, and uses the gear ring of the two-stage planetary gear set to distinguish between first gear and second gear, so that the shifting mechanism can be arranged between the differential unit and the deceleration unit, which has the advantages of high energy density and high integration.

[0013] 2. The solution provided by the present invention includes multiple planetary gear sets, including differential units and reduction units, arranged in parallel. The overall structure is compact and the motor position can be easily adjusted according to the space constraints of the lateral or bus. It has the advantages of small installation space and higher reliability. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the differential electric drive assembly based on a planetary gear set in Example 1; Figure 2 It is a power flow diagram of the differential function electric drive assembly based on the planetary gear set; Figure 3 This is a two-speed power flow diagram of a differential electric drive assembly based on a planetary gear set; Figure 4 This is a schematic diagram of the differential electric drive assembly based on a planetary gear set in Example 2.

[0015] The following components are labeled in the diagram: Drive unit 1, Motor 11, First-stage gear 12, First-stage shaft 13, Differential unit 2, First-stage planetary gear set 21, Second-stage planetary gear set 22, First drive shaft 23, Second drive shaft 24, First reduction unit 3, Second reduction unit 4, First-stage planetary gear set 41, Second-stage planetary gear set 42, Shifting mechanism 5, First-stage gear 51, Second-stage gear 52, Sliding sleeve 53. Detailed Implementation

[0016] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0017] Example 1, please refer to Figures 1 to 3 These are, respectively, the schematic diagram of the differential electric drive assembly based on planetary gear set provided by the present invention and its first and second gear power flow diagrams.

[0018] The differential electric drive assembly based on planetary gear sets includes a drive unit 1, a differential unit 2, a first reduction unit 3, a second reduction unit 4, and a shifting mechanism 5.

[0019] The drive unit 1 includes a motor 11, a primary gear 12, and a primary shaft 13.

[0020] The shaft ends of the two motors 11 are respectively equipped with pinions, which mesh with the same primary gear 12. The primary gear 12 is connected to the differential unit 2 through the primary shaft 13.

[0021] Differential unit 2 includes a first-stage planetary gear set 21 and a second-stage planetary gear set 22 arranged side by side.

[0022] The first-stage shaft 13 is connected to the sun gear of the first-stage planetary gear 21 from the left. The planet carriers of the first-stage planetary gear 21 and the second-stage planetary gear 22 are connected to each other. The first drive shaft 23 extending to the left is located at the center of the planet carrier of the second-stage planetary gear 22. The first drive shaft 23 passes through the second-stage planetary gear 22, the first-stage planetary gear 21, and the first-stage shaft 13 in sequence, and is connected to the first reduction unit 3.

[0023] The first reduction unit 3 is a planetary gear set. The sun gear of the first reduction unit 3 is connected to the first drive shaft 23, the planet carrier is fixed, and the ring gear is output on the left side.

[0024] The gear ring of the second-stage planetary gear set 22 is smaller than that of the first-stage planetary gear set 21, and the planet gears are also correspondingly smaller. The second-stage planetary gear set 22 does not require a sun gear. The gear rings of the first-stage planetary gear set 21 and the second-stage planetary gear set 22 are joined together on the right side and connected to the shifting mechanism 5. The gear ring of the second-stage planetary gear set 22 is joined together on the left, and the gear ring of the first-stage planetary gear set 21 is joined together on the right.

[0025] The shifting mechanism 5 has a second drive shaft 24 in the middle, which is a double-layer shaft. Specifically, the shifting mechanism 5 includes a first gear 51 and a second gear 52. The first gear 51 includes two rings aligned in position, with the outer ring located on the gear ring of the second-stage planetary gear set 22 and the inner ring located on the inner left end of the second drive shaft 24; the second gear 52 includes two rings aligned in position, with the outer ring located on the gear ring of the first-stage planetary gear set 21 and the inner ring located on the outer left end of the second drive shaft 24.

[0026] The shifting mechanism 5 also includes a sliding sleeve 53 and a control system for controlling the movement of the sliding sleeve 53. When the control system moves the sliding sleeve 53 between the inner and outer rings of the first gear 51, the gear ring of the second-stage planetary gear set 22 is connected to the inner layer of the second drive shaft 24, serving as the first gear of the electric drive assembly; when the control system moves the sliding sleeve 53 between the inner and outer rings of the second gear 52, the gear ring of the first-stage planetary gear set 21 is connected to the outer layer of the second drive shaft 24, serving as the second gear of the electric drive assembly; when the control system moves the sliding sleeve 53 between the first gear 51 and the second gear 52, neither the gear rings of the first-stage planetary gear set 21 nor the second-stage planetary gear set 22 are connected, serving as the neutral gear of the electric drive assembly.

[0027] The second reduction unit 4 includes a first-gear planetary gear set 41 and a second-gear planetary gear set 42 arranged side-by-side. The outer layer of the second drive shaft 24 connects to the sun gear of the second-gear planetary gear set 42 from the left. The inner layer of the second drive shaft 24 extends through the outer layer of the second drive shaft 24 and continues through the second-gear planetary gear set 42 until it connects to the sun gear of the first-gear planetary gear set 41 from the left. The planet carriers of the first-gear planetary gear set 41 and the second-gear planetary gear set 42 are interconnected, with the planet carrier of the second-gear planetary gear set 42 outputting from the right side. The gear rings of both the first-gear planetary gear set 41 and the second-gear planetary gear set 42 are fixed.

[0028] Based on the above structure, the power generated by the motor 11 drives the sun gear of the differential unit 2 via the first-stage gear 12 and the first-stage shaft 13, and is further output to both sides from the planet carrier and ring gear of the differential unit 2 to achieve power distribution. One path output through the planet carrier drives the sun gear of the first reduction unit 3 and is output from the ring gear of the first reduction unit 3.

[0029] The output path of the gear ring is further divided into two directions: under the switching mechanism 5, in first gear, the sun gear of the first gear planetary set 41 is driven from the gear ring of the second-stage planetary set 22 and the inner layer of the second drive shaft 24, and the output is from the planet carrier of the first gear planetary set 41; in second gear, the sun gear of the second gear planetary set 42 is driven from the gear ring of the first-stage planetary set 21 and the outer layer of the second drive shaft 24, and the output is from the planet carrier of the second gear planetary set 42.

[0030] Assume the speed ratio x of the first gear 12, the speed ratio characteristic parameter of the differential unit 2 is m in first gear and n in second gear, the speed ratio characteristic parameter k of the first reduction unit 3, the speed ratio characteristic parameter a of the first planetary gear set 41, and the speed ratio characteristic parameter b of the second planetary gear set 42.

[0031] When in first gear, the output speed ratio of the first reduction unit 3 is: x*(1+m)*k; The output speed ratio of the second reduction unit 4 is: x*m*(1+a).

[0032] When in second gear, the output speed ratio of the first reduction unit 3 is: x*(1+n)*k; The output speed ratio of the second deceleration unit 4 is: x*n*(1+b).

[0033] By using an appropriate gear ratio, the speed ratios of the left and right wheels are made the same, i.e., (1+m)*k=m*(1+a) and (1+n)*k=n*(1+b), thus satisfying the condition that the differential speed does not differ from the torque and realizing the differential function.

[0034] Example 2: Please refer to Figure 4 This is a schematic diagram of the differential electric drive assembly based on a planetary gear set provided by the present invention in this embodiment.

[0035] The differential electric drive assembly based on planetary gear sets includes a drive unit 1, a differential unit 2, a first reduction unit 3, a second reduction unit 4, and a shifting mechanism 5.

[0036] The drive unit 1 includes a motor 11, and the shaft end of the motor 11 is directly connected to the differential unit 2.

[0037] Differential unit 2 includes a first-stage planetary gear set 21 and a second-stage planetary gear set 22 arranged side by side.

[0038] The motor 11 is connected to the sun gear of the first-stage planetary gear 21 from the left. The planet carriers of the first-stage planetary gear 21 and the second-stage planetary gear 22 are connected to each other. The center of the planet carrier of the second-stage planetary gear 22 is provided with a first drive shaft 23 extending to the left. The first drive shaft 23 passes through the second-stage planetary gear 22, the first-stage planetary gear 21, and the motor 11 in sequence, and is connected to the first reduction unit 3.

[0039] The other structures are the same as in Example 1.

[0040] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A differential electric drive assembly based on a planetary gear set, characterized in that: The system includes a drive unit, a differential unit, and two reduction units. The differential unit includes a first-stage planetary gear set and a second-stage planetary gear set arranged side by side. The planet carrier of the first-stage planetary gear set is connected to the planet carrier of the second-stage planetary gear set. The ring gear of the second-stage planetary gear set is smaller than the ring gear of the first-stage planetary gear set. The sun gear of the first-stage planetary gear set is connected to the drive unit. The planet carrier of the second-stage planetary gear set is connected to one of the reduction units. The ring gears of the first-stage and second-stage planetary gear sets are connected to the same shift mechanism and are connected to the other reduction unit through the shift mechanism.

2. The differential electric drive assembly based on a planetary gear set according to claim 1, characterized in that: The planet carrier of the secondary planetary gear set is equipped with a first drive shaft, which passes through the secondary planetary gear set, the primary planetary gear set, and the drive unit in sequence, and is connected to the reduction unit, referred to as the first reduction unit; the shifting mechanism is connected to a second drive shaft, which is connected to another reduction unit, referred to as the second reduction unit.

3. The differential electric drive assembly based on a planetary gear set according to claim 2, characterized in that: The drive unit includes a motor, one end of which is directly connected to the sun gear of the first-stage planetary gear set. The first drive shaft passes through the second-stage planetary gear set, the first-stage planetary gear set, and the motor in sequence.

4. The differential electric drive assembly based on a planetary gear set according to claim 2, characterized in that: The drive unit includes a motor and a transmission gear set. One or more of the motors are connected to the sun gear of the first-stage planetary set through the same transmission gear set. The first drive shaft passes through the second-stage planetary set, the first-stage planetary set, and the transmission gear set in sequence.

5. The differential electric drive assembly based on a planetary gear set according to any one of claims 2 to 4, characterized in that: The second drive shaft is a double-layer shaft. The gear ring of the second-stage planetary gear set is connected to the inner layer of the second drive shaft through the shifting mechanism, and the gear ring of the first-stage planetary gear set is connected to the outer layer of the second drive shaft through the shifting mechanism.

6. The differential electric drive assembly based on a planetary gear set according to claim 5, characterized in that: The shifting mechanism connects the gear ring of the second-stage planetary gear set with the inner layer of the second drive shaft, which is designated as first gear; or connects the gear ring of the first-stage planetary gear set with the outer layer of the second drive shaft, which is designated as second gear; or neither is connected, which is designated as neutral.

7. The differential electric drive assembly based on a planetary gear set according to claim 6, characterized in that: The shifting mechanism includes a first gear tooth, a second gear tooth, a sliding sleeve, and a control system. The first gear tooth is simultaneously located on the gear ring of the second-stage planetary gear set and the inner layer of the second drive shaft. The second gear tooth is simultaneously located on the gear ring of the first-stage planetary gear set and the outer layer of the second drive shaft. The control system moves the sliding sleeve to engage with the first gear tooth at two locations simultaneously to achieve first gear. Moving the sliding sleeve to engage with the second gear tooth at two locations simultaneously to achieve second gear. Moving the sliding sleeve to a position where it does not contact the first gear tooth or the second gear tooth simultaneously to achieve neutral gear.

8. The differential electric drive assembly based on a planetary gear set according to claim 6 or 7, characterized in that: Both the first reduction unit and the second reduction unit are planetary gear sets. The first reduction unit outputs a gear ring, and the second reduction unit outputs a planet carrier.

9. The differential electric drive assembly based on a planetary gear set according to claim 8, characterized in that: The second deceleration unit includes a second-speed planetary gear set and a first-speed planetary gear set arranged side by side. The gear rings of the second-speed planetary gear set and the first-speed planetary gear set are fixed. The planet carrier of the second-speed planetary gear set is connected to the planet carrier of the first-speed planetary gear set and outputs from the planet carrier.

10. The differential electric drive assembly based on a planetary gear set according to claim 9, characterized in that: The inner layer of the second drive shaft is connected to the sun gear of the first-gear planetary gear set, and the outer layer of the second drive shaft is connected to the sun gear of the second-gear planetary gear set.

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