Four-wheel drive vehicle rear axle power system and gear control method

Abstract

The four-wheel drive vehicle rear axle power system and gear control method disclosed by the present invention only use a clutch that needs to be controlled, and use a one-way clutch that does not need to be controlled to replace a general clutch to achieve two-speed power transmission. It has a simple structure, small volume, and low cost, and can effectively reduce the vehicle control system. For realizing gear shifting, during the combination and disconnection process of the clutch and the one-way clutch, since the one-way clutch has the ability to transmit torque unidirectionally, it avoids the overload slip of the clutch, and can also reduce the control difficulty.

Description

Technical Field

[0001] The present invention relates to four-wheel drive vehicles, and more particularly to a power system and a gear control method for the rear axle of a four-wheel drive vehicle. Background Art

[0002] In the power system of the rear axle of an existing four-wheel drive vehicle, the drive motor transmits power to the front sun gear and the rear sun gear through the first clutch and the second clutch respectively to achieve a two-gear function. Therefore, two clutches are used to achieve power transmission in two gears. The structures of the two clutches are complex, occupying a large space. The control system required to meet the power switching of the two gears is complex. In order to reduce the overload slip during gear shifting, the requirements for the control system are high when the two clutches are combined and disengaged. To meet the shifting performance requirements, wet clutches are often used for the two clutches, which have complex structures and high costs. Summary of the Invention

[0003] The present invention discloses a power system for the rear axle of a four-wheel drive vehicle, which has a simple structure, simple control, and low cost, and realizes power transmission in two gears.

[0004] The present invention also discloses a gear control method according to the power system of the rear axle of a four-wheel drive vehicle, which has a simple structure, simple control, and low cost, and realizes power transmission in two gears.

[0005] The power system for the rear axle of a four-wheel drive vehicle disclosed by the present invention includes a drive motor, a dual clutch, an inner shaft, an outer shaft, and a planetary gear set;

[0006] The dual clutch includes a clutch and a one-way clutch;

[0007] The planetary gear set includes a front sun gear, a rear sun gear, front planet gears and rear planet gears fixedly arranged side by side on the left and right, a planet carrier with planet shafts, a ring gear, and an output shaft;

[0008] The front planet gears and the rear planet gears are sleeved on the planet shafts of the planet carrier; the front sun gear meshes with the front planet gears, the rear sun gear meshes with the rear planet gears; the ring gear meshes with the rear planet gears; the output end of the planet carrier is fixed to the output shaft;

[0009] The inner shaft is sleeved inside the outer shaft and extends beyond both ends of the outer shaft;

[0010] The inner hub of the clutch is fixedly connected to the rear sun gear through the fixed inner shaft; the inner race of the one-way clutch is fixedly connected to the front sun gear through the fixed outer shaft;

[0011] The drive motor is fixedly connected to the outer drum of the clutch and the outer race of the one-way clutch through the motor shaft.

[0012] Further, the clutch and the one-way clutch are arranged side by side on the left and right.

[0013] Furthermore, the clutch is a dry clutch.

[0014] Furthermore, the clutch is a dry electromagnetic clutch.

[0015] Furthermore, the clutch is a dry hydraulic clutch.

[0016] The present invention also discloses a gear control method for the rear axle power system of the four-wheel drive vehicle according to the above.

[0017] In the first gear: The drive motor operates, the outer drum and the inner hub of the clutch are disengaged, and the outer race and the inner race of the one-way clutch are engaged; the power of the drive motor is transmitted to the front sun gear through the one-way clutch. The front planet gear and the rear planet gear rotate around the planet gear shaft of the planet carrier and revolve around the center line of the front sun gear at the same time. When the ring gear is fixed and does not rotate, the power of the drive motor passes through the motor shaft, the one-way clutch, the outer shaft, the front sun gear, the front planet gear, the rear planet gear, the planet shaft and the planet carrier in sequence, and finally the power is output through the output shaft.

[0018] In the second gear: The drive motor operates, the outer drum and the inner hub of the clutch are engaged, and the outer race and the inner race of the one-way clutch are disengaged; the power is transmitted to the rear sun gear through the clutch. The rear planet gear rotates around the planet gear shaft of the planet carrier and revolves around the center line of the rear sun gear at the same time. When the ring gear is fixed and does not rotate, the power of the drive motor passes through the motor shaft, the clutch, the inner shaft, the rear sun gear, the rear planet gear, the planet shaft and the planet carrier in sequence, and finally the power is output through the output shaft.

[0019] When shifting gears:

[0020] When shifting from the first gear to the second gear, the clutch gradually engages, the transmission ratio of the power system decreases, the inner race of the one-way clutch 4 overspeed the outer race, so that the inner race and the outer race of the one-way clutch gradually disengage, and at the same time the clutch further engages until it is fully engaged, and the whole shifting ends, and the vehicle shifts into the second gear.

[0021] When shifting from the second gear to the first gear, the engaged clutch gradually disengages, and at the same time the disengaged one-way clutch gradually engages until the clutch is fully disengaged and the one-way clutch is fully engaged, and the vehicle shifts into the first gear.

[0022] The beneficial technical effects of the present invention are:

[0023] 1) Only one clutch to be controlled is adopted, and a one-way clutch that does not require control is used instead of a general clutch to achieve power transmission in two gears. Its structure is simple, the volume is small, and the cost is low. It can effectively reduce the automotive control system. For gear shifting, during the combination and disconnection process of the clutch and the one-way clutch, since the one-way clutch has the ability to transmit torque unidirectionally, it can avoid the overload slip of the clutch, and can also reduce the control difficulty of the control system.

[0024] 2) When shifting from the first gear to the second gear, the clutch gradually combines, the transmission ratio of the power system decreases, the inner race of the one-way clutch runs faster than the outer race, so that the inner race and the outer race of the one-way clutch gradually disconnect, and at the same time the clutch further combines until it is completely combined. The whole process does not require additional control of the one-way clutch, realizing the simplicity of control.

[0025] 3) The clutch is a dry clutch. The dry clutch has a low manufacturing cost, simple control, and high mechanical transmission efficiency. The clutch is a dry electromagnetic clutch, and the electromagnetic clutch can be connected to the electronic control system of the vehicle, and its response is extremely fast. Or the clutch is a dry hydraulic clutch. The control of the electromagnetic clutch and the hydraulic clutch is simple and stable. The dry hydraulic clutch can be connected to the hydraulic system of the vehicle. It can transmit a large torque and has a smaller volume. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a schematic structural diagram of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0027] The present invention will be described in detail below with reference to the drawings.

[0028] See Figure 1 , the four-wheel drive vehicle rear axle power system disclosed by the present invention includes a drive motor 1, a dual clutch, an inner shaft 6, an outer shaft 5 and a planetary gear set.

[0029] The dual clutch includes a clutch 3 and a one-way clutch 4, and the clutch 3 and the one-way clutch 4 are arranged side by side left and right.

[0030] The planetary gear set includes a front sun gear 7, a rear sun gear 12, front planet gears 8 and rear planet gears 11 fixedly arranged side by side left and right, a planet carrier 14 with a planet shaft 13, a ring gear 10 and an output shaft 15;

[0031] The front planet gear 8 and the rear planet gear 11 are sleeved on the planet shaft 13 of the planet carrier 14; the front sun gear 7 meshes with the front planet gear 8, and the rear sun gear 12 meshes with the rear planet gear 11; the ring gear 10 meshes with the rear planet gear 11; the output end of the planet carrier 14 is fixed to the output shaft 15. The number of teeth of the front sun gear 7 is less than that of the rear sun gear 12, the number of teeth of the front planet gear 8 is more than that of the rear planet gear 11, and the ring gear 10 is fixed on the transmission housing 9 and does not rotate.

[0032] The inner shaft 6 is sleeved inside the outer shaft 5 and extends beyond both ends of the outer shaft 5.

[0033] The inner hub of the clutch 3 is fixedly connected to the rear sun gear 12 through the inner shaft 6; the inner race of the one-way clutch 4 is fixedly connected to the front sun gear 7 through the outer shaft 5;

[0034] The drive motor 1 is fixedly connected to the outer drum of the clutch 3 and the outer race of the one-way clutch 4 through the motor shaft 2.

[0035] The clutch 3 can adopt a dry clutch, a dry electromagnetic clutch or a dry hydraulic clutch.

[0036] The present invention also discloses a gear control method according to the power system of the rear axle of a four-wheel drive vehicle.

[0037] In the first gear: the drive motor 1 works, the outer drum and the inner hub of the clutch 3 are disengaged, and the outer race and the inner race of the one-way clutch 4 are engaged; the power of the drive motor 1 is transmitted to the front sun gear 7 through the one-way clutch 4. The front planet gear 8 and the rear planet gear 11 rotate around the planet shaft 13 of the planet carrier 14 and revolve around the center line of the front sun gear 7 at the same time. When the ring gear 10 is fixed and does not rotate, the power of the drive motor 1 passes through the motor shaft 2, the one-way clutch 4, the outer shaft 5, the front sun gear 7, the front planet gear 8, the rear planet gear 11, the planet shaft 13 and the planet carrier 14 in sequence, and finally the power is output through the output shaft 15. At this time, the first gear transmission ratio is formed; the power route of the first gear: drive motor 1, motor shaft 2, one-way clutch 4, outer shaft 5, front sun gear 7, front planet gear 8, rear planet gear 11, planet shaft 13, planet carrier 14, output shaft 15.

[0038] When in the second gear: The drive motor 1 operates, the outer drum and the inner hub of the clutch 3 are engaged, and the outer race and the inner race of the one-way clutch 4 are disengaged; the power is transmitted to the rear sun gear 12 through the clutch 3. The rear planet gear 11 rotates around the planet gear shaft 13 of the planet carrier 14 while revolving around the center line of the rear sun gear 12. When the ring gear 10 is fixed and does not rotate, the power of the drive motor 1 sequentially passes through the motor shaft 2, the clutch 3, the inner shaft 6, the rear sun gear 12, the rear planet gear 11, the planet shaft 13 and the planet carrier 14, and finally the power is output through the output shaft 15. At this time, the second-gear transmission ratio is formed; the second-gear power route: drive motor 1, motor shaft 2, clutch 3, inner shaft 6, rear sun gear 12, rear planet gear 11, planet shaft 13, planet carrier 14, output shaft 15.

[0039] Gear shift: When the vehicle is running in the first gear, the vehicle running state is known according to relevant sensors, and then a judgment is made. If acceleration is required, it will enter the second gear. The specific gear shift is as follows: When the vehicle running in the first gear reaches the shift point to shift into the second gear, the clutch 3 gradually engages, the transmission ratio of the power system decreases, the inner race of the one-way clutch 4 overspeed the outer race, so that the inner race and the outer race of the one-way clutch 4 gradually disengage, and at the same time the clutch 3 further engages until it is fully engaged, and the whole gear shift ends, and the vehicle shifts into the second gear. The process of the vehicle shifting from the second gear to the first gear is exactly the reverse of the process of shifting into the second gear. Specifically as follows: When the vehicle running in the second gear needs to shift into the first gear, the engaged clutch 3 gradually disengages, and at the same time the disengaged one-way clutch 4 gradually engages until the clutch 3 is fully disengaged and the one-way clutch 4 is fully engaged, and the whole gear shift ends, and the vehicle shifts into the first gear.

[0040] During the vehicle running in the first gear, when encountering a special section, the wheel speed is too high and reverse dragging occurs. At this time, the speed of the drive motor 1 can be reduced, and at the same time the engagement of the clutch 3 is controlled to achieve stable power transmission.

[0041] The present invention only uses a clutch that needs to be controlled, and uses a one-way clutch that does not need to be controlled to replace a general clutch to realize the power transmission of two gears. Its structure is simple, the volume is small, the cost is low, and it can effectively reduce the vehicle control system. To achieve gear shift, the combination and disengagement process of the clutch and the one-way clutch. Since the one-way clutch has the ability to transmit torque unidirectionally, it avoids the overload slip of the clutch, and can also reduce the control difficulty of the control system.

[0042] When shifting from the first gear to the second gear, the clutch gradually engages, the transmission ratio of the power system decreases, the inner race of the one-way clutch overspeed the outer race, so that the inner race and the outer race of the one-way clutch gradually disengage, and at the same time the clutch further engages until it is fully engaged. The whole process does not require additional control of the one-way clutch, realizing the simplicity of control.

[0043] The clutch 3 is a dry clutch. The dry clutch has a low manufacturing cost, simple control, and high mechanical transmission efficiency. The clutch 3 is a dry electromagnetic clutch, which can be connected to the electronic control system of the vehicle and has an extremely fast response. Or the clutch 3 is a dry hydraulic clutch. The control of both the electromagnetic clutch and the hydraulic clutch is simple and stable. The dry hydraulic clutch can be connected to the hydraulic system of the vehicle, can transmit a large torque, and has a smaller volume.

Claims

1. Four-wheel drive vehicle rear axle power system, characterized in that: It includes a driving motor (1), a dual clutch, an inner shaft (6), an outer shaft (5) and a planetary gear set; The dual clutch includes a clutch (3) and a one-way clutch (4), and the clutch (3) is a dry hydraulic clutch; The inner shaft (6) is sleeved inside the outer shaft (5) and extends beyond both ends of the outer shaft (5); The inner hub of the clutch (3) is fixedly connected to the rear sun gear (12) through the inner shaft (6); The inner race of the one-way clutch (4) is fixedly connected to the front sun gear (7) through the outer shaft (5); The driving motor (1) is fixedly connected to the outer drum of the clutch (3) and the outer race of the one-way clutch (4) through the motor shaft (2), and the clutch (3) and the one-way clutch (4) are arranged side by side left and right; The planetary gear set includes a front sun gear (7), a rear sun gear (12), front planet gears (8) and rear planet gears (11) fixedly connected and arranged side by side left and right, a planet carrier (14) with a planet shaft (13), a ring gear (10) and an output shaft (15); The front planet gears (8) and the rear planet gears (11) are sleeved on the planet shaft (13) of the planet carrier (14); the front sun gear (7) meshes with the front planet gears (8), and the rear sun gear (12) meshes with the rear planet gears (11); the ring gear (10) meshes with the rear planet gears (11); the output end of the planet carrier (14) is fixedly connected to the output shaft (15); In the first gear: The driving motor (1) operates, the outer drum and the inner hub of the clutch (3) are disengaged, and the outer race and the inner race of the one-way clutch (4) are engaged; the power of the driving motor (1) is transmitted to the front sun gear (7) through the one-way clutch (4). The front planet gears (8) and the rear planet gears (11) rotate around the planet shaft (13) of the planet carrier (14) and revolve around the center line of the front sun gear (7) at the same time. When the ring gear (10) is fixed and does not rotate, the power of the driving motor (1) passes through the motor shaft (2), the one-way clutch (4), the outer shaft (5), the front sun gear (7), the front planet gears (8), the rear planet gears (11), the planet shaft (13) and the planet carrier (14) in sequence, and finally the power is output through the output shaft (15); In the second gear: The driving motor (1) operates, the outer drum and the inner hub of the clutch (3) are engaged, and the outer race and the inner race of the one-way clutch (4) are disengaged; the power is transmitted to the rear sun gear (12) through the clutch (3). The rear planet gears (11) rotate around the planet shaft (13) of the planet carrier (14) and revolve around the center line of the rear sun gear (12) at the same time. When the ring gear (10) is fixed and does not rotate, the power of the driving motor (1) passes through the motor shaft (2), the clutch (3), the inner shaft (6), the rear sun gear (12), the rear planet gears (11), the planet shaft (13) and the planet carrier (14) in sequence, and finally the power is output through the output shaft (15); When shifting gears: When shifting from the first gear to the second gear, the clutch (3) gradually engages, the transmission ratio of the power system decreases, the inner race of the one-way clutch (4) rotates faster than the outer race, causing the inner and outer races of the one-way clutch (4) to gradually disengage. At the same time, the clutch (3) further engages until it is fully engaged, and the entire shifting process is completed, and the vehicle shifts into the second gear; When shifting from the second gear to the first gear, the engaged clutch (3) gradually disengages, and at the same time, the disengaged one-way clutch (4) gradually engages until the clutch (3) is completely disengaged and the one-way clutch (4) is fully engaged, and the vehicle shifts into the first gear.

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