Vehicle starting and stopping device and control method thereof

Abstract

The invention discloses a vehicle starting and stopping device and a control method. The vehicle starting and stopping device comprises an input electromagnetic clutch assembly, a volute spring, a bypass speed reduction transmission mechanism, an output electromagnetic clutch assembly and a controller, and the bypass speed reduction transmission mechanism is connected with the outer end of the volute spring and the input electromagnetic clutch assembly; the input electromagnetic clutch assembly comprises a first friction clutch and a first one-way clutch, the first friction clutch controls on-off of power transmission between an output shaft of the gearbox and the bypass speed reduction transmission mechanism, and the first one-way clutch limits the outer end of the volute spring to only rotate in the energy storage direction. The output electromagnetic clutch assembly comprises a second friction clutch and a second one-way clutch, the second friction clutch is used for locking or releasing the inner end of the volute spring, and the second one-way clutch limits the inner end of the volute spring to only drive the input shaft of the gearbox to operate during forward rotation. Braking energy is recycled through the volute spring and used for starting the engine, and the influence on braking force is reduced.

Description

Technical Field

[0001] The present invention relates to a vehicle start-stop device and a control method thereof, belonging to the technical field of vehicle transmission. Background Art

[0002] Traditional gasoline-powered vehicles, lacking energy storage devices, need to idle while waiting at traffic lights, wasting energy and increasing exhaust emissions. Existing technologies use batteries with automatic start-stop functionality in conjunction with engine automatic start-stop technology to reduce idling during stops. However, these devices still fail to effectively utilize braking energy to achieve emission reductions.

[0003] Other existing technologies use a spiral spring energy storage device to recover braking energy and release it at the appropriate time, thereby improving fuel economy and reducing fuel consumption and exhaust emissions. However, the spiral spring energy storage device has a low storage energy density and stores little energy, making the use of the spiral spring to assist in driving the vehicle minimal. Furthermore, the auxiliary driving force decreases as the deformation angle of the spiral spring decreases, making the driving force difficult to control. When recovering braking energy, the spiral spring generates an auxiliary braking force, which increases as the deformation angle of the spiral spring increases, making the distribution and control of the braking force during vehicle braking very difficult. When the spiral spring energy storage device reaches saturation, the auxiliary braking force suddenly disappears, potentially causing the vehicle to lose control of its braking. Summary of the Invention

[0004] To address the aforementioned shortcomings of the prior art, the present invention aims to provide a vehicle start-stop device that recovers energy during the vehicle's braking and stopping process for engine starting when the vehicle is started, thereby reducing starting energy consumption. Another objective of the present invention is to provide a control method for a vehicle start-stop device that addresses the control difficulties caused by variations in auxiliary braking force, or even the sudden disappearance of stored energy after saturation.

[0005] The technical solution of the present invention is as follows: A vehicle start-stop device includes an input electromagnetic clutch assembly, a volute spring, a bypass reduction transmission mechanism, an output electromagnetic clutch assembly, and a controller. The input end of the bypass reduction transmission mechanism is a gear I, and the output end of the bypass reduction transmission mechanism is a slewing bearing. The input end of the bypass reduction transmission mechanism performs a reduction transmission to the output end. The ring gear of the slewing bearing is connected to the outer end of the volute spring. The input electromagnetic clutch assembly includes a first friction clutch and a first one-way clutch. The first friction clutch is connected between the output shaft of the vehicle's gearbox and the gear 1 to control the on / off transmission of power between the output shaft of the gearbox and the gear 1. The first one-way clutch limits the gear 1 to rotate only in the direction in which the volute spring stores energy. The output electromagnetic clutch assembly includes a second friction clutch and a second one-way clutch, wherein the second friction clutch is used to lock or release the inner end of the volute spring, and the second one-way clutch is connected between the input shaft of the gearbox and the inner end of the volute spring. The second one-way clutch limits the inner end of the volute spring to only drive the input shaft of the gearbox in forward rotation and idles in reverse rotation; The controller is used for controlling the disengagement and engagement of the first friction clutch and the second friction clutch.

[0006] Furthermore, the output electromagnetic clutch assembly includes a motor structure and a fourth shaft. The motor structure includes a stator housing and a rotor. The stator housing is fixed to the inner end of the volute spring. The rotor is sleeved on the fourth shaft, which is connected to the input shaft of the gearbox. When the rotor rotates relative to the fourth shaft, it moves axially along the fourth shaft. This axial movement of the rotor along the fourth shaft controls the engagement and disengagement of the second friction clutch. Using the motor structure to drive the axial movement of the rotor to engage and disengage the second friction clutch provides smoother operation.

[0007] Furthermore, the rotor and the fourth shaft are provided with mutually cooperating threaded structures to form a threaded transmission pair. When the threaded structure of the rotor and the threaded structure of the fourth shaft have a second axial gap, the second friction clutch engages to lock the inner end of the volute spring; when the threaded structure of the rotor and the threaded structure of the fourth shaft eliminate the second gap and generate relative rotation, the second friction clutch disengages to release the inner end of the volute spring.

[0008] Furthermore, the stator housing is provided with a second electromagnetic coil, and the rotor is provided with a second armature disk. When the second electromagnetic coil is energized, it attracts the second armature disk and pushes the rotor to move axially to eliminate the second gap.

[0009] Furthermore, the second friction clutch includes a second friction disc group and a second steel disc group, the second friction disc group is fixedly arranged, and the second steel disc group is connected to the stator housing via a spline.

[0010] Furthermore, the second friction clutch includes a diaphragm spring, and the rotor and the second armature plate pull the diaphragm spring to deform so as to eliminate the pressure between the second steel plate group and the second friction plate group to disengage the second friction clutch.

[0011] Furthermore, the bypass reduction transmission mechanism includes a plurality of gears and a double cross-axis transmission shaft, and the double cross-axis transmission shaft is arranged on one side of the gearbox.

[0012] Another technical solution of the present invention is as follows: A control method for a vehicle start-stop device, based on the aforementioned vehicle start-stop device, includes: when it is necessary to recover braking energy, engaging the first friction clutch, keeping the second clutch in a normally engaged state, and having the output shaft of the gearbox drive the outer end of the volute spring to rotate through the bypass reduction transmission mechanism to store energy; when it is necessary to start the engine, disengaging the second friction clutch, and having the inner end of the volute spring drive the input shaft of the gearbox to rotate through the stator housing to release energy.

[0013] Furthermore, the need to recover braking energy is determined by the following steps: the brake pedal is depressed while the engine is not shut down and the vehicle speed is lower than a preset minimum stable speed; before engaging the first friction clutch, the stored energy of the spiral spring is determined, and the engine is shut down when the stored energy of the spiral spring is greater than the energy required to start the engine once; otherwise, the engine is not shut down.

[0014] Furthermore, before engaging the first friction clutch, the difference between the maximum stored energy of the spiral spring and the stored energy of the spiral spring is determined, and the first friction clutch is engaged only when the difference exceeds the braking energy recovered once.

[0015] The advantages of the present invention compared with the prior art are: This invention uses a first one-way clutch in the input electromagnetic clutch to allow braking energy to be input into the volute spring while preventing stored energy from being released. A second one-way clutch in the output electromagnetic clutch allows the fourth shaft (which also includes the transmission input shaft) to rotate freely during normal vehicle operation. Simultaneously, when the volute spring releases energy, the fourth shaft is driven through the stator housing to start the engine. Using a volute spring to store braking energy offers a simple structure, ease of implementation, high reliability, and maintenance-free operation.

[0016] The bypass reduction transmission mechanism adopts a two-stage gear reduction to increase torque, so that the high-rigidity spiral spring produces a smaller auxiliary braking force, which has little impact on the vehicle's braking performance and can also store more energy to meet the needs of multiple engine starts. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Schematic diagram of the structure of the vehicle start-stop device of the embodiment.

[0018] Figure 2 Schematic diagram of the structure of the input electromagnetic clutch assembly of the vehicle start-stop device of the embodiment.

[0019] Figure 3 Schematic diagram of the structure of the bypass reduction transmission mechanism of the vehicle start-stop device of the embodiment.

[0020] Figure 4 for Figure 3 Schematic diagram of the A-direction structure.

[0021] Figure 5 Schematic diagram of the structure of the output electromagnetic clutch assembly of the vehicle start-stop device of the embodiment.

[0022] Figure 6 Schematic diagram of the spiral spring energy storage calculation model.

[0023] Figure 7 2 is a flow chart of a control method for a vehicle start-stop device according to an embodiment. DETAILED DESCRIPTION

[0024] The present invention will be further described below with reference to the examples, but are not intended to limit the present invention.

[0025] Please combine Figures 1 to 5 As shown, the vehicle start-stop device involved in this embodiment mainly includes an output electromagnetic clutch assembly 1, a volute spring 2, a bypass reduction transmission mechanism, an input electromagnetic clutch assembly 3, a tension sensor 11, and a controller. The controller is not shown in the drawings and can use an existing chip with computing capabilities on the vehicle. The output electromagnetic clutch assembly 1 is mounted on the input shaft 402 of the vehicle's transmission 4, and the input electromagnetic clutch assembly 3 is mounted on the output shaft 401 of the vehicle's transmission 4. One end of the volute spring 2 is connected to the bypass reduction transmission mechanism via the tension sensor 11, and the other end is connected to the input electromagnetic clutch assembly 3. The input electromagnetic clutch inputs kinetic energy into the volute spring 2 for storage via the bypass reduction transmission mechanism. When needed, the volute spring 2 releases energy to drive the input shaft 402 of the transmission 4. The specific connection between these components is shown in the detailed structural description of each component.

[0026] like Figure 2As shown, the input electromagnetic clutch assembly 3 includes an inner housing 301, a first steel plate assembly 302, a first friction plate assembly 303, a first one-way clutch sprag assembly 304, a first pressure plate 305, an outer housing 306, a clutch housing 307, a disc spring 308, a first armature plate 309, a first electromagnetic coil 310, a coil holder 311, and a first shaft 312. The outer housing 306 is fixedly connected to the housing of the transmission case 4 and its extension components by bolts. The inner housing 301 is also connected to the gear 15 by bolts. The outer cylindrical surface of the inner housing 301, the first one-way clutch sprag assembly 304, and the inner cylindrical surface of the outer housing 306 constitute a first one-way clutch, allowing the gear 15 to rotate in one direction. The inner housing 301 is machined with internal splines that mate with the external splines of the first steel plate assembly 302. Several first friction plate assemblies 303 are spaced apart between the multiple layers of first steel plates 302. The internal splines of the first friction plate assembly 303 mate with the external splines of the first shaft 312, forming a first multi-plate friction clutch. The rightmost side of the first steel plate assembly 302 is equipped with a first pressure plate 305. This pressure plate 305 is connected to the outer edge of a disc spring 308 via screws evenly spaced around its circumference. The inner edge of the disc spring 308 is connected to the first armature plate 309 via screws evenly spaced around its circumference. The clutch housing 307 is bolted to the right end of the inner housing 301. The right side of the clutch housing 307 houses the first electromagnetic coil 310 and its coil holder 311, which is supported on the first shaft 312 via bearings. The left end of the first shaft 312 is splined to the output shaft of the transmission 4, while the right end is connected to the vehicle's drive shaft (not shown) via splines and a flange. When the first electromagnetic coil 310 is de-energized, the disc spring 308 remains free, a gap forms between the first pressure plate 305 and the steel plate, and the first multi-plate friction clutch disengages. The engine's power is transmitted to the vehicle's drivetrain via the transmission 4 and the first shaft 312, allowing the vehicle to travel normally. When the first electromagnetic coil 310 is energized, the first armature plate 309 moves rightward under the action of the electromagnetic force. The disc spring 308, using the central protrusion of the clutch housing 307 as a fulcrum, pushes the first pressure plate 305 leftward to compress the first steel plate assembly 302. Friction is generated between the first steel plate assembly 302 and the first friction plate assembly 303, and power is transmitted to the gear 15 via the first shaft 312, the first multi-plate friction clutch, and the inner housing 301.

[0027] like Figure 3 and Figure 4As shown, the bypass reduction transmission mechanism includes gear I 5, gear II 6, gear III 7, a slewing bearing 8, a second shaft 9, and a third shaft 10. Second shaft 9 is supported on the housing of the transmission case 4 and its extension member via a pair of bearings. The journal of second shaft 9 engages with the internal splines of gear II 6 via an external spline. The left end of second shaft 9 engages with the internal splines of the flange via an external spline and is axially positioned by a nut. Gear II 6 meshes with gear I 5. The middle portion of third shaft 10 is supported on the housing of transmission case 4 via a pair of bearings. Third shaft 10 is a double-cross transmission shaft capable of transmitting power between intersecting shafts, facilitating layout. The left end of second shaft 9 is connected to the right end of third shaft 10. The left end of third shaft 10 engages with the internal splines of gear III 7 via an external spline and is axially positioned by a nut. Gear III 7 meshes with the inner gear ring of slewing bearing 8 to transmit power. The outer ring of slewing bearing 8 is connected to the engine cylinder block via bolts evenly spaced around the circumference, while the inner gear ring of slewing bearing 8 is also connected to the connecting plate via bolts evenly spaced around the circumference. Two volute spring supports are welded to the connecting plate and bolted to tension sensor 11. The other end of tension sensor 11 is bolted to the outer end of volute spring 2. The inner end of volute spring 2 is bolted to the stator housing 104 of the output electromagnetic clutch assembly 1.

[0028] Please combine Figure 5As shown, the structure of the output electromagnetic clutch assembly 1 includes a fourth shaft 101, a spline cylinder 102, a second one-way clutch wedge block group 103, a stator housing 104, a motor winding 105, a rotor 106, a needle roller bearing 107, a second armature plate 108, a clutch housing 109, a retaining ring, a locking flange 110, a second steel plate group 111, a second friction plate group 112, a second pressure plate 113, a diaphragm spring 114, motor winding contacts, a second electromagnetic coil 115, and a release bearing 116. As shown in the figure, the fourth shaft 101 includes, from left to right, sections A, B, C, D, and E. Section A is supported in the flywheel's inner bore via bearings. Section B's external splines mate with the internal splines of the engine's clutch hub (not shown). Section C's external splines mate with the internal splines of spline cylinder 102. Section D is machined with rectangular external threads. Section E of the fourth shaft 101 extends rearward into the transmission 4, becoming the transmission's input shaft 402. A second one-way clutch sprag assembly 103 is installed between the outer cylindrical surface of spline cylinder 102 and the inner cylindrical surface of stator housing 104, forming a second one-way clutch that only allows one-way rotation of the fourth shaft 101. The right end of stator housing 104 houses motor winding 105, forming a DC motor with rotor 106. Section F of the left end of rotor 106 also features rectangular internal threads, which mate with the rectangular external threads of section D of the fourth shaft 101 to form a threaded transmission pair. The inner cylindrical surface of rotor 106 in the middle is supported on the cylindrical surface of section E of the fourth shaft 101 via needle roller bearing 107. A second electromagnetic coil 115 is embedded in the left end of the clutch housing 109. The right end of the clutch housing 109 features internal splines that mate with the external splines of the second steel plate assembly 111. Several second friction plate assemblies 112 are spaced apart between the second steel plate assemblies 111. The internal splines of these second friction plate assemblies 112 mate with the external splines of the locking flange 110 and are axially restrained by a retaining ring, forming the second multi-plate friction clutch. A second pressure plate 113 is mounted to the left side of the leftmost second steel plate 111. A raised center portion of this second pressure plate 113 rests on the center portion of a diaphragm spring 114. The outer ring of this diaphragm spring 114 rests within the clutch housing 109, while its inner ring rests on a release bearing 116. The second steel plate assembly 111, second friction plate assembly 112, second pressure plate 113, and diaphragm spring 114 are assembled via a retaining ring, compressing the diaphragm spring 114 and causing it to deform, providing the initial clamping force for the second multi-plate friction clutch. A release bearing 116 is mounted within the central inner hole of the second armature plate 108. The left end surface of the second armature plate 108 is bolted to the rotor 106. When the second electromagnetic coil 115 is de-energized, the second multi-plate friction clutch is engaged. The stator housing 104, clutch housing 109, and locking flange 110 are frictionally connected, and the stator housing 104 is locked.When the second electromagnetic coil 115 is energized, the electromagnetic force generated attracts the second armature plate 108 to move left, and the first gap δI between the release bearing 116 and the diaphragm spring 114 is eliminated. The motor winding contacts are connected, the motor winding 105 is energized, and the second electromagnetic coil 115 is de-energized, and the rotor 106 rotates. At this time, the second gap δII between the end of the rotor 106 and the fourth shaft 101 is also eliminated. The threaded pair pulls the inner edge of the diaphragm spring 114 to the left through the rotor 106 and the release bearing 116 and separates it from the protrusion in the middle of the second pressure plate 113. The spring pressing force on the second pressure plate 113 and the second steel plate group 111 is eliminated, and the second multi-plate friction clutch is in a disengaged state. The stator housing 104 can rotate freely under the action of the spiral spring 2, and the engine is started by the second one-way clutch. After the engine starts, the speed of fourth shaft 101 rapidly increases and exceeds that of rotor 106. Fourth shaft 101, through the threaded pair, drives rotor 106 to the right until it disengages, creating a gap δII. The gap between diaphragm spring 114 and second pressure plate 113 gradually decreases until it is eliminated. Diaphragm spring 114 compresses second pressure plate 113 and second steel plate assembly 111, engaging the second multi-plate friction clutch and locking stator housing 104. At this point, a gap δI also appears between release bearing 116 and diaphragm spring 114, disconnecting the motor winding contacts and de-energizing motor winding 105, causing rotor 106 to stop rotating.

[0029] Please combine Figure 6 As shown, in the above vehicle start-stop device, the tension detected by the tension sensor is F , the distance from the sensor to the center of the spiral spring 2 is R , then the moment on the volute spring axis 2 is T =2 FR , the torsional stiffness of the spiral spring 2 is known to be k φ Since the spiral spring 2 has good linear torsion characteristics, the torsion angle of the spiral spring 2 can be calculated as φ = T / k φ = 2 FR / k φ , and then the energy stored in the spiral spring 2 can be calculated as E = 2 F 2 R 2 / k φ . Assume that the energy required to start the engine once is E s , the braking energy recovered once is E b The maximum energy that can be stored in the spiral spring 2 is E max .

[0030] Please combine Figure 7 As shown, the control method of the vehicle start-stop device includes the following steps: Step 1), the controller is based on the tension value of the sensor F Calculate the energy stored in spiral spring 2 E .

[0031] Step 2) The controller determines whether the engine is stalled. If the engine is stalled, proceed to step 2.1A; if the engine is not stalled, proceed to step 2.1B.

[0032] In step 2.1 A), determine whether the clutch is engaged. If not, assume the vehicle is waiting for a traffic light and return to step 2.1 A. If engaged, proceed to step 2.2 A.

[0033] Step 2.2A) determines whether the transmission 4 is in neutral. If the transmission 4 is not in neutral, return to step 2.2A and do not start the engine. If the transmission 4 is in neutral, proceed to step 2.3A.

[0034] In step 2.3 A), determine whether the accelerator pedal is depressed. If not, return to step 2.3 A. If so, the driver has the motive to start the engine, so proceed to step 2.4 A.

[0035] Step 2.4 A) Determine the energy stored in spiral spring 2 E Is it greater than the engine starting energy? E s .like E < E s If the energy stored in the start-stop device is not enough to start the engine, return to step 1 and start the engine manually. E > E s The start-stop device stores enough energy to reach step 2.5 A.

[0036] In step 2.5A, the engine fuel supply and power supply circuits are restored, the second electromagnetic coil 115 of the output electromagnetic clutch assembly 1 and the motor winding 105 are energized, and the energy stored in the spiral spring 2 is released to start the engine, and then the process goes to step 2.1B.

[0037] In step 2.1B), determine whether the transmission 4 is in neutral. If the transmission 4 is not in neutral, return to step 2.1B; if the transmission 4 is in neutral, go to step 2.2B.

[0038] In step 2.2 B), determine whether the brake pedal is depressed. If not, return to step 2.2 B. If so, proceed to step 2.3 B.

[0039] In step 2.3B, determine whether the vehicle speed is below the minimum stable speed, which is a pre-set minimum stable speed. If the speed is above the minimum stable speed, it may be normal driving braking, and return to step 2.3B. If the speed is below the minimum stable speed, determine the braking process and proceed to step 2.4B.

[0040] Step 2.4B), determine the energy stored in the spiral spring 2 E Is it greater than the engine starting energy? E s .like E < E s The engine cannot be turned off, go to step 2.7 B; if E > E s The energy stored in the spiral spring 2 is sufficient to start the engine, and the process goes to step 2.5B.

[0041] Step 2.5B), turn off the engine's fuel and power supply circuits, control the engine to shut down, and go to step 2.6B.

[0042] Step 2.6B), determine E max - E Is it greater than E b .like E max - E < E b , the spiral spring 2 stores more energy, no need to recover the braking energy, return to step 1; if E max - E > E b , braking energy needs to be recovered, go to step 2.7B.

[0043] In step 2.7B), the first electromagnetic coil 310 of the input electromagnetic clutch assembly 3 is energized, and the vehicle transmission shaft drives the volute spring 2 to recover braking energy, and the process proceeds to step 2.8B.

[0044] In step 2.8B), determine whether the vehicle speed is zero. If the vehicle speed is greater than zero, return to step 2.7B to keep the first electromagnetic coil 310 energized and continue to recover braking energy. If the vehicle speed is zero, the vehicle stops and the process proceeds to step 2.9B.

[0045] In step 2.9B), the first electromagnetic coil 310 of the input electromagnetic clutch assembly 3 is de-energized, and the first shaft 312 resumes free rotation, and the process goes to step 2.

Claims

1. A vehicle start-stop device, characterized in that: It includes an input electromagnetic clutch assembly, a volute spring, a bypass reduction transmission mechanism, an output electromagnetic clutch assembly and a controller, wherein the input end of the bypass reduction transmission mechanism is a gear I, the output end of the bypass reduction transmission mechanism is a slewing bearing, the input end of the bypass reduction transmission mechanism performs reduction transmission to the output end, and the gear ring of the slewing bearing is connected to the outer end of the volute spring; The input electromagnetic clutch assembly includes a first friction clutch and a first one-way clutch, wherein the first friction clutch is connected between the output shaft of the gearbox of the vehicle and the gear 1 to control the on-off of the power transmission between the output shaft of the gearbox and the gear 1, and the first one-way clutch limits the gear 1 to rotate only in the direction in which the volute spring stores energy; The output electromagnetic clutch assembly includes a second friction clutch and a second one-way clutch, wherein the second friction clutch is used to lock or release the inner end of the volute spring, the second one-way clutch is connected between the input shaft of the gearbox and the inner end of the volute spring, and the second one-way clutch limits the inner end of the volute spring to only drive the input shaft of the gearbox to operate in forward rotation, and idles in reverse rotation; The controller is used for controlling the disengagement and engagement of the first friction clutch and the second friction clutch.

2. The vehicle start-stop device according to claim 1, characterized in that: The output electromagnetic clutch assembly includes a motor structure and a fourth shaft. The motor structure includes a stator housing and a rotor. The stator housing is fixed to the inner end of the spiral spring. The rotor is sleeved on the fourth shaft. The fourth shaft is connected to the input shaft of the gearbox. When the rotor rotates relative to the fourth shaft, it moves axially along the fourth shaft. The axial movement of the rotor along the fourth shaft controls the disengagement and engagement of the second friction clutch.

3. The vehicle start-stop device according to claim 2, characterized in that: The rotor and the fourth shaft are provided with mutually matching threaded structures to form a threaded transmission pair. When the threaded structures of the rotor and the fourth shaft have a second axial gap, the second friction clutch engages to lock the inner end of the volute spring; when the threaded structures of the rotor and the fourth shaft eliminate the second gap and generate relative rotation, the second friction clutch disengages to release the inner end of the volute spring.

4. The vehicle start-stop device according to claim 3, characterized in that: The stator housing is provided with a second electromagnetic coil, and the rotor is provided with a second armature plate. When the second electromagnetic coil is energized, the second armature plate is attracted to push the rotor to move axially to eliminate the second gap.

5. The vehicle start-stop device according to claim 4, characterized in that: The second friction clutch comprises a second friction disc group and a second steel disc group, the second friction disc group is fixedly arranged, and the second steel disc group is connected to the stator housing through a spline.

6. The vehicle start-stop device according to claim 5, characterized in that: The second friction clutch includes a diaphragm spring. The rotor and the second armature plate pull the diaphragm spring to deform so as to eliminate the pressure between the second steel plate group and the second friction plate group to separate the second friction clutch.

7. The vehicle start-stop device according to claim 1, characterized in that: The bypass reduction transmission mechanism includes a plurality of gears and a double cross-axis transmission shaft, and the double cross-axis transmission shaft is arranged on one side of the gearbox.

8. A method for controlling a vehicle start-stop device as claimed in claim 1, characterized in that: The vehicle start-stop device according to any one of claims 1 to 7 includes engaging the first friction clutch when braking energy needs to be recovered, keeping the second clutch in a normally engaged state, and driving the outer end of the volute spring to rotate and store energy through the bypass reduction transmission mechanism by the output shaft of the gearbox; and disengaging the second friction clutch when the engine needs to be started, and driving the input shaft of the gearbox to rotate and release energy by the inner end of the volute spring through the stator housing.

9. The control method of the vehicle start-stop device according to claim 8, characterized in that: The need to recover braking energy is determined by the following steps: the brake pedal is depressed when the engine is not turned off and the vehicle speed is lower than a preset minimum stable vehicle speed; before engaging the first friction clutch, the stored energy of the spiral spring is determined, and the engine is turned off when the stored energy of the spiral spring is greater than the energy required to start the engine once, otherwise the engine is not turned off.

10. The control method of the vehicle start-stop device according to claim 9, characterized in that: Before engaging the first friction clutch, the difference between the maximum stored energy of the spiral spring and the stored energy of the spiral spring is determined, and the first friction clutch is engaged only when the difference exceeds the braking energy recovered once.

Images