Transmission of a battery-electric vehicle with clutch function

Abstract

A transmission of a battery-electric vehicle with a disengagement function, comprising an input shaft, an output shaft and an intermediate shaft, wherein an input shaft gear is arranged around the input shaft and the input shaft engages with an intermediate gear on the intermediate shaft via the input shaft gear, the intermediate gear engages with an output gear on the output shaft, the input shaft is connected to an auxiliary drive motor and the output shaft is connected to vehicle wheels; and the transmission further comprises a synchronizing device, wherein a clutch sleeve of the synchronizing device is driven by a shifting mechanism to switch between an engaged position in which the clutch sleeve engages with the input shaft gear and a disengaged position in which the clutch sleeve does not engage with the input shaft gear;The shifting mechanism comprises a BLDC motor, a shift wheel and a shift fork; the shift wheel is driven by the BLDC motor to cause the shift fork to move linearly, and the shifting of the clutch sleeve of the synchronizing device with respect to the input shaft wheel is caused by the linear movement of the shift fork.

Description

TECHNICAL AREA

[0001] The disclosure pertains to the technical field of drive units for battery electric vehicles and relates in particular to the field of transmissions of drive units for battery electric vehicles. BACKGROUND

[0002] Since 2020, new energy vehicles have experienced explosive growth and are gaining increasing acceptance among users. Most high-performance battery electric vehicles (BAVs) utilize an all-wheel-drive structure, which is not found in traditional fuel-powered vehicles. The battery electric vehicle is equipped with a motor and a transfer case. All-wheel-drive battery electric vehicles employ two independent sets of electric drive units, one at the front and one at the rear.

[0003] In the battery-electric vehicle with all-wheel drive, the front and rear electric drive units can be powered independently. The all-wheel drive or two-wheel drive mode can be selected via a control system. Front and rear drive units can be engaged simultaneously in situations such as overspeed, inclines, and similar conditions. Only the main drive unit can be used under normal operating conditions.

[0004] However, in conventional four-wheel-drive vehicles, if the auxiliary drive lacks a disengagement function, several adverse consequences can occur when the auxiliary drive is not engaged. First, when the auxiliary drive is not engaged, it is pulled away from the wheels to spin at high speed, causing additional friction and transmission oil mixing losses as the transmission gear, bearings, and motor rotor rotate at high speed. Second, this high-speed idling also reduces the lifespan of the components. Third, in a motor using a permanent magnet, the permanent magnet will generate eddy current losses in the stator core, and the motor will be in a discharge state. If the speed is too high, the back EMF will increase the DC line voltage.In general, the overvoltage problem is solved by a weak magnetic current, which also introduces copper losses, or otherwise capacitor and IGBT breakdown risks.

[0005] To address the problems mentioned above caused by the permanent magnet motor, some companies use an induction motor as an auxiliary drive, but the induction motor has low efficiency at low speeds and under light loads, and its control is complex. SUMMARY

[0006] In view of the shortcomings of a battery electric vehicle with all-wheel drive, the disclosure provides a design scheme for a battery electric vehicle transmission with a disengagement function that effectively solves all of the above-mentioned problems and improves the range of the entire vehicle and the lifespan of a drive unit.

[0007] The operating principle of the disclosure can be described as follows. In the battery-electric vehicle with all-wheel drive, the disengagement function is added to a transmission system of the auxiliary drive unit, and the auxiliary drive can be in an operating state or in a disengaged state depending on the driving requirements of the vehicle.

[0008] The disengagement function of the disclosure can be described as follows. A miniaturized brushless direct current (BLDC) motor and a reduction mechanism are used to rotate a shift wheel to drive a shift fork, and the shift fork drives a synchronizing device and a clutch sleeve to achieve power transmission and interruption of a gear wheel.

[0009] This function allows the auxiliary drive of the all-wheel drive vehicle to have two gears: a forward gear (gear D) and a neutral gear (gear N).

[0010] When the battery electric vehicle is operating with all-wheel drive, the above auxiliary drive can be equipped with a disengagement function to achieve instant switching between two-wheel drive and all-wheel drive under different operating conditions, reducing the overall vehicle's power consumption and increasing its range.

[0011] The disengagement function of the disclosure can be further described as follows: The automation control is implemented by a microcontroller unit (MCU), a BLDC angle sensor, a shift fork position sensor, and an input shaft gear speed sensor. The MCU is configured to control the auxiliary drive motor for output and to control the BLDC motor to drive a disengagement mechanism to disengage the output shaft from the output shaft gear when a battery-electric vehicle is shifted from gear D to gear N. The shift fork position sensor monitors the position of the shift fork and transmits data to the MCU during the execution process. The motor angle sensor in the BLDC motor calculates a precise angle of movement and transmits the data to the MCU.The MCU is designed to control the speed of the auxiliary drive motor so that it matches the speed of the output shaft wheel, according to a signal sent by the speed sensor of the input shaft wheel when the auxiliary drive is moved from gear N to gear D. The MCU then controls the BLDC motor to perform the engagement of the synchronizer until the BLDC angle sensor and the shift fork position sensor confirm that the auxiliary drive motor is entering its normal operating state after the gear change is complete. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 is an axial diagram of a gear with a disengagement function and a disengagement mechanism; Fig. Figure 2 is a schematic diagram of the transmission and disengagement of the gear with a disengagement function; Fig. Figure 3 is a schematic diagram of the transmission of the gear with a disengagement function; Fig. 4 is a schematic diagram of the disengagement mechanism; and Fig. Figure 5 is a schematic diagram of an intermediate shaft with the disengagement mechanism.

[0012] Numerical reference symbols are shown as follows: 301 refers to input shaft, 302 refers to deep groove ball bearing, 303 refers to shift fork, 304 refers to synchronizer, 305 refers to input shaft gear, 306 refers to needle bearing, 307 refers to deep groove ball bearing, 308 refers to bushing, 309 refers to locking pin, 310 refers to intermediate shaft large gear, 311 refers to intermediate shaft, 312 refers to tapered roller bearing, 313 refers to differential ring gear, 314 refers to differential, 315 refers to tapered roller bearing, 401 refers to BLDC motor, 402 refers to disengagement mechanism gear, 403 refers to cam, 404 refers to shift fork, 405 refers to shift fork shaft, and 204 refers to Shift fork position sensor. DETAILED DESCRIPTION

[0013] The technical solution in the embodiments of the disclosure is hereby clearly and completely described with reference to the accompanying drawings in the embodiments of the disclosure. Obviously, the described embodiments are some, but not all, embodiments of the disclosure. All other embodiments that can be derived by those skilled in the art from the embodiments of the disclosure without creative effort are all to fall within the scope of protection of the disclosure.

[0014] As in Fig. 2, Fig. 3 and Fig. Figure 4 shows a battery-electric vehicle transmission with a disengagement function comprising mainly an input shaft 301, an input shaft bearing 302, a needle bearing 306, a synchronizing device 304, an input shaft gear 305, an intermediate shaft 311, a large gear 310 of the intermediate shaft, a differential ring gear 313, a differential 314, a BLDC motor 401, a gear 402 of the disengagement mechanism, a shift wheel 403, a shift fork 404, a shift fork shaft 405, a shift fork position sensor 204, a speed sensor 409 and the like.

[0015] The power transmission will continue with reference to Fig. As described in Figure 3, the input shaft 301 is coupled to a motor shaft. The input shaft is pressed against the synchronizing device 304 and the input shaft gear 305. The needle bearing 306 is installed between the input shaft gear 305 and the input shaft 301. The input shaft gear 305 engages with the large gear 310 of the intermediate shaft. The large gear 310 of the intermediate shaft and the intermediate shaft 311 are integrated via a splined shaft or an interference fit. The small gear of the intermediate shaft 311 engages with the differential ring gear 313. The shift gear 403 is provided with a guide groove. The shift fork 404 is provided with a guide block that is aligned with the guide groove. The linear movement of the shift fork 404 is achieved by this alignment when the shift gear 403 rotates.

[0016] When the transmission is in gear D, the synchronizer 304 moves downwards to allow the clutch sleeve to engage with the input shaft gear 305. At this point, the power from the auxiliary drive motor can be transmitted via the clutch sleeve in the synchronizer to the input shaft gear 305, then via the intermediate shaft 311 to the differential ring gear 313, and finally to the wheels.

[0017] When the transmission is in neutral (N), the synchronizer moves upwards to disengage the clutch sleeve from the input shaft 301. At this point, if the vehicle is moving, the input shaft gear 305 is driven in reverse to rotate upside down on the input shaft 301 without rotating the input shaft and the auxiliary drive motor.

[0018] With reference to Fig. Section 4 further describes the shifting function and structure. The shifting mechanism with a disengagement function is driven by the miniaturized BLDC motor 401, delayed by a secondary gear 202, drives the shift wheel 403 to rotate, and then drives the shift fork 404 to move through the guide groove of the shift wheel 403 in order to disengage / engage the synchronizing device 408 from / with the engagement gear, thus completing the shift between gear N and gear D of the transmission.

[0019] When the vehicle needs to be shifted from gear D to gear N while in motion, the MCU controls the output of the auxiliary drive motor, and the BLDC motor 401 drives the disengagement mechanism to disengage the input shaft 412 from the input shaft gear 410. During the execution process, the shift fork position sensor (204 in Fig. 2) The position of the shift fork to ensure correct execution. Furthermore, the motor angle sensor in the BLDC motor can accurately calculate the angle of movement.

[0020] When the auxiliary drive needs to be shifted from gear N to gear D, a motor controls its speed so that it matches the speed of the output shaft gear, according to a signal sent by the speed sensor of the input shaft gear to ensure successful engagement of the input shaft gear with the engagement gear of the synchronizer device. Then the BLDC motor performs the engagement of the synchronizer device until the BLDC angle sensor and the shift fork position sensor confirm that the drive motor is entering its normal operating state after the gear change is complete.

[0021] In Fig. 4 The needle bearing is installed between the input shaft gear and the input shaft, the axial limit of the needle bearing is controlled by a bushing 412, the bushing 412 is secured on the input shaft via a hollow bolt, which can ensure that lubricating oil can enter the input shaft via a central hole of the hollow bolt and lubricates a needle through an axial oil bore.

[0022] The disclosure further provides a drive control method for a battery-electric vehicle, wherein the battery-electric vehicle is an all-wheel-drive structure and is equipped with a transmission featuring a disengagement function as described above. The disengagement function can be implemented by the automation control system using a microcontroller unit (MCU), a BLDC angle sensor, a shift fork position sensor, and an input shaft gear speed sensor. The MCU is configured to control the auxiliary drive motor for output and to control the BLDC motor to drive a disengagement mechanism to disengage the output shaft from the output gear when a battery-electric vehicle is shifted from gear D to gear N while in motion. The shift fork position sensor monitors the position of the shift fork and transmits data to the MCU during the execution process to ensure accurate execution.The motor angle sensor in the BLDC motor can accurately calculate the angle of movement and transmit the data to the MCU to ensure precise execution. The MCU is configured to control the speed of the auxiliary drive motor to match the speed of the output shaft gear, according to a signal sent by the input shaft gear speed sensor when the auxiliary drive is engaged from gear N to gear D. The MCU then controls the BLDC motor to engage the synchronizer until the BLDC angle sensor and the shift fork position sensor confirm that the auxiliary drive motor has returned to its normal operating state after the gear change is complete.

[0023] The above descriptions represent preferred embodiments of the disclosure, but are not intended to limit the scope of protection of the disclosure. All technical solutions that are part of the concept of the disclosure are intended to fall within its scope of protection. As in Fig. As shown in Figure 5, the synchronizing device is installed in the large gear of the intermediate shaft, and the input shaft gear and the input shaft are integrated, which can also ensure the implementation of the disclosure and should also fall within the scope of protection of the disclosure.

Claims

[1] A transmission of a battery-electric vehicle with a disengagement function, comprising an input shaft, an output shaft and an intermediate shaft, wherein an input shaft gear is arranged around the input shaft and the input shaft engages with an intermediate gear on the intermediate shaft via the input shaft gear, the intermediate gear engages with an output gear on the output shaft, the input shaft is connected to an auxiliary drive motor and the output shaft is connected to vehicle wheels; and the transmission further comprises a synchronizing device, wherein a clutch sleeve of the synchronizing device is driven by a shifting mechanism to switch between an engaged position in which the clutch sleeve engages with the input shaft gear and a disengaged position in which the clutch sleeve does not engage with the input shaft gear;The shifting mechanism comprises a BLDC motor, a shift wheel and a shift fork; the shift wheel is driven by the BLDC motor to cause the shift fork to move linearly, and the shifting of the clutch sleeve of the synchronizing device with respect to the input shaft wheel is caused by the linear movement of the shift fork. [2] The transmission of the battery electric vehicle with a disengagement function according to claim 1, wherein the output shaft is a differential and the intermediate gear engages with a differential ring gear. [3] The transmission of the battery electric vehicle with a disengagement function according to claim 1, wherein a needle bearing is arranged between the input shaft gear and the input shaft. [4] The transmission of the battery electric vehicle with a disengagement function according to claims 2 to 3, further comprising a microcontroller unit (MCU), a BLDC angle sensor, a shift fork position sensor and an input shaft wheel speed sensor to implement automation control, wherein the MCU is configured to drive the auxiliary drive motor to output and to drive the BLDC motor to drive a disengagement mechanism to disengage the output shaft from an output shaft wheel when a battery electric vehicle in motion is shifted from gear D to gear N, the shift fork position sensor monitors a position of the shift fork and transmits data to the MCU in an execution process, the motor angle sensor in the BLDC motor calculates exactly an angle of movement and transmits the data to the MCU;The MCU is designed to control the speed of the auxiliary drive motor so that it is consistent with the speed of the output shaft wheel according to a signal sent by the speed sensor of the input shaft wheel when the auxiliary drive is shifted during a movement from gear N to gear D. The MCU then controls the BLDC motor to perform the engagement of the synchronizer until the BLDC angle sensor and the shift fork position sensor confirm that the auxiliary drive motor is entering a normal operating state after the gear shift is complete. [5] The transmission of the battery electric vehicle with a disengagement function according to claim 1, wherein the shift wheel is provided with a guide groove, the shift fork is provided with a guide block which is aligned with the guide groove, and the linear movement of the shift fork is realized by the alignment when the shift wheel rotates.

Images