CN210265006U - Anti-drag starting device for engine and engine - Google Patents

Abstract

The utility model discloses an anti-drag starting device of an engine and the engine, wherein a clutch gear meshing pair is arranged on a transmission chain for starting a transmission assembly; the clutch gear meshing pair comprises a driving clutch gear and a driven clutch gear, and the driving clutch gear is arranged on a clutch gear shaft in a transmission fit manner through a spiral pair; the helix angle of the helix pair ensures that the helix pair has no self-locking capability; the utility model avoids the recoil caused by the reverse rotation of the engine to directly act on the starting transmission system; the lift angle of the screw pair is reasonably arranged, the problem that the return is not flexible due to the fact that the lift angle is too small is avoided, return interference is avoided, the problem of component damage caused by the backflushing caused by the reverse rotation of the engine is thoroughly solved, the whole starting system is simple and compact in structure, the stress state of a foot system is improved, the backflushing can be avoided, the foot system can be smoothly separated or meshed, the service life of the system is prolonged, and the use and maintenance cost is reduced.

Description

Anti-drag starting device for engine and engine

Technical Field

The utility model relates to an engine part, in particular to engine prevent anti-starting drive and engine that drags.

Background

For an engine, the engine is started by electricity in a more commonly adopted starting mode, and a starting motor is utilized to drive a crankshaft to rotate and transmit torque to the engine, so that the engine is started. In the anti-drag starting device of the engine in the prior art, in order to ensure that the started engine runs normally and does not drag a starting motor and start a transmission system to run, an overrunning clutch (one-way clutch) is arranged on a transmission chain. However, when the engine is used for a load-carrying vehicle, the problem of engine reverse rotation caused by vehicle flameout can occur in a specific occasion, when the engine rotates reversely, the rotating speed of a crankshaft is transmitted to a starter motor through an overrunning clutch (a one-way clutch), the starter motor generates a sign of large rotating speed due to the large transmission ratio (the transmission ratio is about 6.2) of the electric starting system, the one-way clutch bears large impact load, the one-way clutch is easy to damage, and meanwhile, the electric starting system can be impacted disadvantageously. The engine stalls and recoils, which causes the slip or locking problem of the isolator in a short period (one month of engine use), and the isolator fails.

Therefore, the existing anti-drag starting device of the engine needs to be improved, when the engine is used for a load-carrying vehicle, under the condition of the recoil formed by flameout and reversal of the engine, the recoil can not be formed on an electric starting system, the service life of the system is prolonged, the use and maintenance cost is saved, the structure is optimized, and the cost is reduced.

SUMMERY OF THE UTILITY MODEL

In view of this, the utility model provides an engine prevents anti-starting drive and engine that drags, when the engine was used for load vehicle, under the recoil condition that the engine stalled the reversal formation, can not form the recoil to electric starting system, the life of extension system to practice thrift and use and maintenance cost, and optimize the structure, reduce self cost simultaneously.

The utility model discloses an anti-drag starting device of an engine, which comprises a starting motor and a starting transmission assembly for transmitting the starting power of the starting motor to a crankshaft, wherein a clutch gear meshing pair is arranged on a transmission chain of the starting transmission assembly;

the clutch gear meshing pair comprises a driving clutch gear and a driven clutch gear, and the driving clutch gear is arranged on a clutch gear shaft in a transmission fit manner through a spiral pair; when the clutch gear shaft is started, the driving clutch gear is driven by the spiral pair to move axially to be in meshed transmission with the driven clutch gear when the clutch gear shaft rotates, and after the starting is finished, the driving clutch gear is driven to return and is separated from the driven clutch gear;

the gear pair formed by the driving clutch gear and the driven clutch gear can be located at any position of a transmission chain of the starting transmission assembly theoretically and can play a role in disconnecting reverse rotation transmission, but in order to reduce impact on components in actual use, the gear pair is located at the rear end of the output of starting power as far as possible and is close to a crankshaft of an engine;

the rotation direction of the spiral pair is based on the requirement of meshing to propel the driving clutch gear to move to the driven clutch gear when the clutch gear shaft rotates, and the details are not repeated;

in the structure, when the electric starting is carried out, the starting motor inputs power into the starting transmission assembly, so that the power is input into the clutch gear shaft, the clutch gear shaft drives the driving clutch gear to axially move through the screw pair to be meshed with the driven clutch gear while rotating, so that the starting power is transmitted to the engine crankshaft (the transmission to the engine crankshaft is realized in various modes, and can be realized through gears, direct connection or other intermediate parts), and the starting is realized; after the engine is started, the starting motor is stopped, the engine runs power and returns back to drive the driven clutch gear to rotate, so that the driving clutch gear is driven to rotate, the engine returns along the axial direction of the clutch gear shaft under the action of a spiral pair, the transmission chain is disengaged and disconnected, and at the moment, the engine is flamed out and reversely rotated, so that no influence is caused on the starting of a transmission system; of course, if the active clutch gear is provided with an active return, the effect of disengaging the engagement is better.

Furthermore, the driving clutch gear is provided with a return pretightening force, and the return pretightening force has a tendency of separating the driving clutch gear from the driven clutch gear; the direction of the return pretightening force is towards the direction of separating the two gears, the active clutch gear is returned, the return pretightening force helps the active clutch gear to return by combining the setting of the helix angle, a stable separation structure is formed, the interference generated during the operation is avoided, and the whole starting system is protected from being impacted.

Furthermore, the driving clutch gear is provided with a friction piece, the friction piece is used for forming friction force with the driving clutch gear, and the friction piece is arranged for forming friction on the driving clutch gear and has certain torque so as to ensure that the driving clutch gear cannot follow up easily when the clutch gear shaft rotates, thereby ensuring smooth clutch; the friction member may be in various forms, such as an elastic friction member, which is fixedly disposed with respect to a fixed member such as a case, and which causes a set rotational resistance to the driving clutch gear.

Furthermore, the helix angle of the helix pair enables the helix pair not to have self-locking capability, the helix pair is formed by helix fit, and whether the helix fit can be self-locked or not has a direct relation with the helix angle; in the structure, parameters of a helix angle are controlled, so that the helix pair can not be self-locked, the return of the active clutch gear after the completion of starting is facilitated, and the disengagement is ensured to be thorough, and the starting system including a starting motor is prevented from being impacted when an engine rotates reversely.

The starting transmission assembly further comprises a first-stage driven gear and a second-stage driving gear which are meshed through an end face cam pair, the first-stage driven gear is meshed with the first-stage driven gear in a transmission mode, the second-stage driven gear is meshed with the second-stage driving gear in a transmission mode, the second-stage driven gear inputs power to a clutch gear shaft, and the first-stage driving gear is used for inputting starting power of a starting motor; the end face cam pair is of a sawtooth meshing structure, is in transmission meshing in the starting direction and is in inclined plane matching in the opposite starting direction; the existing duplicate gear is changed into a split structure and has the functions of separation and meshing; when the transmission is started normally, the end face cam pair is used for transmission, when the switch is started by mistake, the motor is started to drive the driving clutch gear to be meshed with the driven clutch gear, the engine rotates back, the back transmission rotating speed enables the rotating speed of the second-stage driving gear to exceed the rotating speed of the first-stage driving gear due to the setting of the transmission ratio, and the end face cam pair is matched through an inclined plane to form overrunning, so that the impact caused by the rotating speed of the engine during the mistake starting is avoided; of course, the primary driven gear and/or the secondary driving gear are required to have an axial movement allowance, and the allowance ensures that the inclined plane is matched to not transmit power and has a return pretightening force.

Furthermore, the end face cam pair is formed by matching a sawtooth-shaped end face cam arranged on the end face of a shaft neck formed by the primary driven gear and a sawtooth-shaped end face cam arranged on the end face of a shaft neck formed by the secondary driving gear, the primary driven gear or/and the secondary driving gear are/is provided with a meshing pre-tightening force for driving the end face cam to mesh, the structure is simple and compact, the shaft neck forms a cam meshing pair, and the stability of axial movement can be guaranteed.

Further, the primary driving gear is arranged on an output shaft of a rotor of the starting motor in a transmission fit manner and is used for inputting starting power of the starting motor; the secondary driven gear is arranged on the clutch gear shaft in a transmission fit manner to input starting power to the clutch gear shaft, and is generally integrally formed; the end face cam pair and the spiral pair are arranged in series, so that the interruption of the recoil caused by the reverse rotation of the engine is ensured, and the recoil can be overtaken in time after the engine is started by mistake; the isolator in the prior art is eliminated, the cost is saved, and the structure of the engine is simplified.

Furthermore, the spiral pair is formed by matching an inner spiral of the driving clutch gear with an outer spiral of the clutch gear shaft, and the return pretightening force is applied by a return spring which is sleeved outside an extending shaft section of the clutch gear shaft, one end of the return pretightening force abuts against the driving clutch gear, and the other end of the return pretightening force is axially fixed relative to the clutch gear shaft; the end part of the return spring is axially fixed by a limiting piece fixed on the clutch gear shaft to abut against the end part of the return spring; as shown in the figure, the clutch driving gear is close to the second-stage driven gear and is arranged on the clutch gear shaft through the spiral pair, the return spring is sleeved at the far end of the clutch gear shaft, the driven clutch gear is located on the other side, opposite to the second-stage driven gear, of the driving clutch gear, the whole structure is compact, the arrangement is reasonable, and the driving clutch gear does not need to be provided with a limiting part which is prevented from being disengaged independently.

Furthermore, the friction piece is a spring friction piece, a spring friction groove is formed in the excircle of the active clutch gear, and the spring friction piece is provided with a fixed end with a set pre-tightening force, embedded in the spring friction groove and extending out of the fixed end; the spring friction piece adjusts a proper pretightening force for applying a friction force to the active clutch gear, of course, the spring should have a fixed end for supporting the generation of the friction force, and the fixed end can be fixed at a specific position of the engine box body according to the installation requirement, and is not described herein again; the clutch and driven gear is directly connected to the magneto rotor in a transmission manner, so that power is transmitted to the crankshaft of the engine, the isolator is removed, and the structure is simple and compact.

Furthermore, the primary driven gear and the secondary driving gear are rotationally matched and sleeved on an intermediate shaft in an externally sleeved mode, the meshing pretightening force is applied by a meshing spring which is sleeved on the intermediate shaft in an externally sleeved mode, one end of the meshing pretightening force abuts against the primary driven gear, and the other end of the meshing pretightening force is axially fixed relative to the intermediate shaft; as shown in the figure, the first-stage driven gear can move axially relative to the intermediate shaft, one end of the meshing spring abuts against a limiting part fixed on the intermediate shaft, and the other end of the meshing spring abuts against the first-stage driven gear tightly and applies pre-tightening force for enabling the first-stage driven gear to move towards the second-stage driving gear, so that meshing separation smoothness is guaranteed.

Further, spring friction spare is the circular and enclosed construction who buckles out the stiff end of main part, and as shown in the figure, spring friction spare main part is circular and imbed spring friction inslot, and circular spring forms radial inward power of cramping, forms the friction, and the outside emergence of circular less part is warp and is formed the stiff end, and this stiff end and circular main part transition form holistic enclosed construction naturally, guarantee that frictional force is lasting and the bulk strength is higher.

The utility model also discloses an engine, the engine adopts the engine prevent anti-starting drive that drags.

The utility model has the advantages that: the anti-drag starting device of the engine and the engine of the utility model adopt the transmission structure which can be separated and meshed, and avoid the direct action of the recoil caused by the reversal of the engine on the starting transmission system; the lift angle of the screw pair is reasonably arranged, the problem that the return is not flexible due to the fact that the lift angle is too small is avoided, return interference is avoided, the problem of component damage caused by the backflushing caused by the reverse rotation of an engine is thoroughly solved, the whole starting system is simple and compact in structure, the stress state of a foot system is improved, the backflushing can be avoided, the foot system can be smoothly separated or meshed, the service life of the system is prolonged, the use and maintenance cost is reduced, the structure is optimized, and meanwhile the cost of the foot system is reduced.

Drawings

The invention is further described with reference to the following figures and examples.

FIG. 1 is a schematic structural diagram of a starting system of the present invention;

FIG. 2 is a schematic view of a one-stage driven gear;

FIG. 3 is a schematic view of a two-stage driving gear structure;

FIG. 4 is a schematic structural view of a clutch gear shaft;

fig. 5 is a schematic view of the structure of the active clutch gear.

Detailed Description

Fig. 1 is a schematic structural view of a starting system of the present invention, fig. 2 is a schematic structural view of a primary driven gear, fig. 3 is a schematic structural view of a secondary driving gear, fig. 4 is a schematic structural view of a clutch gear shaft, and fig. 5 is a schematic structural view of a driving clutch gear; as shown in the figure: the anti-drag starting device of the engine comprises a starting motor 1 and a starting transmission assembly for transmitting starting power of the starting motor 1 to a crankshaft, wherein a transmission chain of the starting transmission assembly is provided with a clutch gear meshing pair;

the clutch gear meshing pair comprises a driving clutch gear 17 and a driven clutch gear 12, and the driving clutch gear 17 is arranged on a clutch gear shaft 10 in a transmission fit manner through a screw pair 16; when the clutch gear shaft 10 is started, the driving clutch gear is driven by the screw pair 16 to move axially to be in meshed transmission with the driven clutch gear, and after the starting is finished, the driving clutch gear 17 is driven to return and is separated from the driven clutch gear 12;

the gear pair formed by the driving clutch gear 17 and the driven clutch gear 12 can be located at any position of a transmission chain of the starting transmission assembly theoretically and can play a role in disconnecting reverse rotation transmission, but in order to reduce impact on components in actual use, the gear pair is located at the rear end of the output of starting power as far as possible and is close to a crankshaft of an engine;

the rotation direction of the screw pair 16 is based on the requirement of meshing to propel the driving clutch gear to move to the driven clutch gear when the clutch gear shaft rotates, and the details are not repeated;

in the structure, when the electric starting is carried out, the starting motor 1 inputs power into the starting transmission assembly, so that the power is input into the clutch gear shaft 10, the clutch gear shaft drives the driving clutch gear to axially move through the screw pair to be meshed with the driven clutch gear while rotating, so that the starting power is transmitted to the engine crankshaft (the transmission to the engine crankshaft is realized in various modes, and can be realized through gears, direct connection or other intermediate parts), and the starting is realized; after the engine is started, the starting motor is stopped, the engine runs power and returns back to drive the driven clutch gear to rotate, so that the driving clutch gear is driven to rotate, the engine returns along the axial direction of the clutch gear shaft under the action of a spiral pair, the transmission chain is disengaged and disconnected, and at the moment, the engine is flamed out and reversely rotated, so that no influence is caused on the starting of a transmission system; of course, if the active clutch gear is provided with an active return, the effect of disengaging the engagement is better.

The helix angle of the helix pair 16 ensures that the helix pair 16 has no self-locking capability, the helix pair is formed by helix fit, and whether the helix fit can be self-locked or not has a direct relation with the helix angle; in the structure, the parameters of the helix angle are controlled, so that the helix pair can not be self-locked, the return of the active clutch gear after the start is finished is facilitated, and the separation is ensured to be more thorough, thereby ensuring that the impact on a starting system including a starting motor is avoided when the engine rotates reversely;

of course, after the screw pair drives the driving clutch gear to reach the meshing position, the screw pair can be structurally set as a head for driving axial movement so as not to form axial driving, the continuous driving of the axial movement is avoided, and a special positioning piece is not required to be arranged.

In this embodiment, the driving clutch gear 17 is provided with a return pre-tightening force, and the return pre-tightening force has a tendency of separating the driving clutch gear 17 from the driven clutch gear 12; the direction of the return pretightening force is towards the direction of separating the two gears, the active clutch gear is returned, the return pretightening force helps the active clutch gear to return by combining the setting of the helix angle, a stable separation structure is formed, the interference generated during the operation is avoided, and the whole starting system is protected from being impacted.

In this embodiment, the driving clutch gear 17 is provided with a friction member, the friction member is used for forming a friction force with the driving clutch gear 17, and the friction member is arranged for forming a friction to the driving clutch gear, so that a certain torque is provided, and the driving clutch gear is not easily followed up when the clutch gear shaft 10 rotates, thereby ensuring smooth clutch; the friction member may be in various forms, such as an elastic friction member, which is fixedly disposed with respect to a fixed member such as a case, and which causes a set rotational resistance to the driving clutch gear.

In this embodiment, the starting transmission assembly further comprises a first-stage driven gear 4 and a second-stage driving gear 2 which are meshed through an end face cam pair 5, a first-stage driving gear 3 is arranged in a meshed transmission mode with the first-stage driven gear 4, a second-stage driven gear 9 is arranged in a meshed transmission mode with the second-stage driving gear 2, the second-stage driven gear 9 inputs power to a clutch gear shaft 10, and the first-stage driving gear 4 is used for inputting starting power of the starting motor 1; the end face cam pair 5 is of a sawtooth meshing structure, is in transmission meshing in the starting direction and is in inclined plane matching in the opposite starting direction; the existing duplicate gear is changed into a split structure and has the functions of separation and meshing; when the transmission is started normally, the end face cam pair is used for transmission, when the switch is started by mistake, the motor is started to drive the driving clutch gear to be meshed with the driven clutch gear, the engine rotates back, the back transmission rotating speed enables the rotating speed of the second-stage driving gear to exceed the rotating speed of the first-stage driving gear due to the setting of the transmission ratio, and the end face cam pair is matched through an inclined plane to form overrunning, so that the impact caused by the rotating speed of the engine during the mistake starting is avoided; of course, the primary driven gear and/or the secondary driving gear are required to have an axial movement allowance, and the allowance ensures that the inclined plane is matched to not transmit power and has a return pretightening force.

In this embodiment, the end cam pair 5 is formed by matching a sawtooth-shaped end cam 501 arranged on the end surface of a journal 401 formed by the first-stage driven gear 4 and a sawtooth-shaped end cam 502 arranged on the end surface of a journal 201 formed by the second-stage driving gear 2, the first-stage driven gear 4 or/and the second-stage driving gear 2 are/is provided with meshing pre-tightening force for driving the end cam pair to mesh, and the meshing pre-tightening force can be independently or both provided, but the pre-tightening force is provided with axial movement allowance, and is not described herein again; the structure is simple and compact, and the shaft neck forms a cam meshing pair, so that the stability of axial movement can be ensured.

In this embodiment, the primary driving gear 3 is disposed on the rotor output shaft of the starting motor 1 in a transmission fit manner, and is used for inputting the starting power of the starting motor 1, as shown in the figure, the embodiment is integrally formed; the secondary driven gear 9 is arranged on the clutch gear shaft in a transmission fit manner to input starting power to the clutch gear shaft, and is generally integrally formed; the end face cam pair 5 and the spiral pair 16 are arranged in series, so that the interruption of the recoil caused by the reverse rotation of the engine is ensured, and the recoil can be overtaken in time after the engine is started by mistake; the isolator in the prior art is eliminated, the cost is saved, and the structure of the engine is simplified.

In this embodiment, the screw pair 16 is formed by matching an inner screw 1602 of the active clutch gear 17 with an outer screw 1601 of the clutch gear shaft 10, and the return pretightening force is applied by a return spring 14 which is externally sleeved on an extending shaft section of the clutch gear shaft and one end of which abuts against the active clutch gear and the other end of which is axially fixed relative to the clutch gear shaft; the end of the return spring 14 is generally fixed axially by a stopper 13 fixed to the clutch gear shaft; as shown in the figure, the clutch driving gear 17 is close to the secondary driven gear 9 and is arranged on the clutch gear shaft 10 through the screw pair 16, the return spring 14 is sleeved at the far end of the clutch gear shaft 10, the driven clutch gear 12 is located on the other side, opposite to the secondary driven gear 9, of the driving clutch gear 17, the whole structure is compact and reasonable in arrangement, and for the driving clutch gear 17, a limiting part for avoiding disengaging is not required to be independently arranged in the structure.

The return spring 14 has an elastic coefficient of a set value, is compressed to a position where the two gears are meshed under the set value, is matched with the helix angle, and has an elastic force capable of preventing the driving clutch gear from continuing to move axially, so that starting meshing can be ensured, and a separate limiting part is not required to be arranged.

In this embodiment, the friction member is a spring friction member 15, a spring friction groove is formed in an outer circle of the active clutch gear 17, and the spring friction member 15 has a fixed end 1501 which has a set pre-tightening force embedded in the spring friction groove and extends out of the spring friction groove and is relatively fixed; the spring friction piece adjusts a proper pretightening force for applying a friction force to the active clutch gear, of course, the spring should have a fixed end for supporting the generation of the friction force, and the fixed end can be fixed at a specific position of the engine box body according to the installation requirement, and is not described herein again; the clutch and driven gear is directly connected to the magneto rotor in a transmission manner, so that power is transmitted to the crankshaft of the engine, the isolator is removed, and the structure is simple and compact.

In this embodiment, the primary driven gear 4 and the secondary driving gear 2 are rotationally matched and sleeved on an intermediate shaft 7, and the meshing pretightening force is applied by a meshing spring 8 which is sleeved on the intermediate shaft 7, one end of the meshing pretightening force abuts against the primary driven gear 4, and the other end of the meshing pretightening force is axially fixed relative to the intermediate shaft; as shown in the figure, the first-stage driven gear 4 should also move axially relative to the intermediate shaft 7, one end of the meshing spring 8 abuts against the limiting part 6 fixed on the intermediate shaft 7, and the other end of the meshing spring abuts against the first-stage driven gear 4 and applies a pre-tightening force to enable the first-stage driven gear to move towards the second-stage driving gear 2, so that meshing separation smoothness is guaranteed.

In this embodiment, the spring friction member 15 is a closed structure with a circular main body and a bent fixed end, as shown in the figure, the spring friction groove is an annular groove formed on a shaft neck of the active clutch gear, the main body of the spring friction member 15 is circular and is embedded into the spring friction groove, the circular spring forms radial inward tightening force to form friction, the circular smaller part deforms outwards to form the fixed end 1501, the fixed end and the circular main body naturally transition to form the integral closed structure, and the durability of the friction force and the high integral strength are ensured.

The utility model also discloses an engine, the engine adopts the engine prevent anti-starting drive that drags, get rid of prior art's isolator, reduce the volume of engine and simplify the assembling process.

Finally, although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the present invention can be modified or replaced by other means without departing from the spirit and scope of the present invention, which should be construed as limited only by the appended claims.

Claims (10)

1. The utility model provides an engine prevents anti-starting drive that drags which characterized in that: the starting transmission assembly comprises a starting motor and a starting transmission assembly, wherein the starting transmission assembly transmits starting power of the starting motor to a crankshaft, and a clutch gear meshing pair is arranged on a transmission chain of the starting transmission assembly;

the clutch gear meshing pair comprises a driving clutch gear and a driven clutch gear, and the driving clutch gear is arranged on a clutch gear shaft in a transmission fit manner through a spiral pair; when the clutch gear shaft is started, the driving clutch gear is driven by the spiral pair to move axially to be in meshed transmission with the driven clutch gear when the clutch gear shaft rotates, and after the starting is finished, the driving clutch gear is driven to return and is separated from the driven clutch gear; the starting transmission assembly further comprises a first-stage driven gear and a second-stage driving gear which are meshed through an end face cam pair, the first-stage driven gear is meshed with the first-stage driving gear in a transmission mode, the second-stage driving gear is meshed with the second-stage driving gear in a transmission mode, the second-stage driven gear inputs power to a clutch gear shaft, and the first-stage driving gear is used for inputting starting power of a starting motor.

2. The engine anti-drag starting device according to claim 1, characterized in that: the driving clutch gear is provided with a return pretightening force, and the return pretightening force has a tendency of separating the driving clutch gear from the driven clutch gear.

3. The engine anti-drag starting device according to claim 2, characterized in that: the driving clutch gear is provided with a friction piece, and the friction piece is used for forming friction force with the driving clutch gear.

4. The engine anti-drag starting device according to claim 1, characterized in that: the helix angle of the helical pair makes the helical pair not have self-locking capability.

5. The engine anti-drag starting device according to claim 1, characterized in that: the end face cam pair is of a sawtooth meshing structure, is in transmission meshing in the starting direction and is in inclined plane matching in the opposite starting direction.

6. The engine anti-drag starting device according to claim 5, characterized in that: the end face cam pair is formed by matching a sawtooth-shaped end face cam arranged on the end face of a shaft neck formed by the primary driven gear with a sawtooth-shaped end face cam arranged on the end face of a shaft neck formed by the secondary driving gear, and the primary driven gear or/and the secondary driving gear are/is provided with meshing pre-tightening force for driving the end face cam to be meshed; the primary driving gear is arranged on a rotor output shaft of the starting motor in a transmission fit mode and is used for inputting starting power of the starting motor; and the secondary driven gear is arranged on the clutch gear shaft in a transmission fit manner and inputs starting power to the clutch gear shaft.

7. The engine anti-drag starting device according to claim 2, characterized in that: the spiral pair is formed by matching an inner spiral of the driving clutch gear with an outer spiral of the clutch gear shaft, the return pretightening force is applied by a return spring which is sleeved outside an extending shaft section of the clutch gear shaft and one end of the return pretightening force props against the driving clutch gear, and the other end of the return pretightening force is axially fixed relative to the clutch gear shaft.

8. The engine anti-drag starting device according to claim 3, characterized in that: the friction piece is a spring friction piece, a spring friction groove is formed in the outer circle of the active clutch gear, and the spring friction piece is provided with a fixed end which is embedded in the spring friction groove and stretches out of the spring friction groove for setting the pre-tightening force.

9. The engine anti-drag starting device according to claim 8, characterized in that: the clutch and driven gear drive is directly connected to a magneto rotor so as to transmit power to an engine crankshaft; the primary driven gear and the secondary driving gear are rotationally matched and sleeved on an intermediate shaft in an externally sleeved mode, the meshing pretightening force is applied by a meshing spring which is sleeved on the intermediate shaft in an externally sleeved mode, one end of the meshing pretightening force abuts against the primary driven gear, and the other end of the meshing spring is axially fixed relative to the intermediate shaft; the spring friction piece is of a closed structure with a round main body and a bent fixed end.

10. An engine, characterized in that: the engine adopts the anti-back-dragging starting device of the engine as claimed in any one of claims 1 to 9.

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