Patent Description:
In recent years, electric vehicles are rapidly developed due to less environmental pollution. At present, most of the electric vehicles are driven by a motor through single-speed reducers. Because of a great speed variation, the motor is required to operate over a great range typically ranging from <NUM> to <NUM>,<NUM> rpm. As restricted by the existing manufacturing technology, a high-speed motor has high cost, and both the motor and a battery have great power. As a result, the existing electric vehicle has higher cost than a conventional fuel vehicle.

When an output torque of a transmission is increased by using a multi-speed transmission with a large reduction ratio at a low speed, and a rotation speed of the motor is reduced by using the multi-speed transmission with a small reduction ratio at a high speed, it is possible to increase an acceleration quality of vehicle power while reducing an operating speed of the motor, thereby lowering the cost of the motor. However, for electric vehicle manufacturers, the multi-speed transmission is more complex than the single-speed reducer. A conventional multi-speed transmission need a clutch, a brake, or a synchronizers to shift, and these traditional transmission components are all required to be controlled by means of complex actuators. A conventional clutch actuator has an electro-hydraulic controlled hydraulic cylinder and a motor-controlled drum shift fork mechanism. For example, <CIT> discloses a synchronous clutch for coupling an auxiliary unit to an internal combustion engine including a first coupling component and a second coupling component, which can be coupled to one another via two friction ring sets. <CIT> discloses a ring of a synchronizing device of a vehicle transmission including a friction surface that interacts with a friction surface of another ring of the synchronizing device and at least one slide surface configured to slidably seat on an abutment surface of the synchronizing device. <CIT> discloses a synchronization device for a change speed gear, including at least one cone clutch which comprises a double cone ring freely rotatable relative to a hub between an inner friction ring and an outer synchronizing ring. <CIT> discloses a gearbox with parallel shafts comprising a primary shaft and at least one secondary shaft supporting several fixed teeth and several idle gears which mesh with the latter and which can be linked in rotation with their shaft by means of coupling when engaging a gear.

The electro-hydraulic proportional-controlled hydraulic oil cylinder can accurately control a torque of the clutch or a torque of the brake to enable a driving torque of a vehicle to be not interrupted during the shifting, and thus the shifting is smooth. However, it is necessary for this type of hydraulic actuator to be supplied with an actuating force by a hydraulic pump, a proportional pressure solenoid valve, a valve plate, and a hydraulic oil cylinder. Moreover, these parts have high cost and great power consumption, and are thus more suitable for a case where a common oil pump is shared by a plurality of clutches. For an electric vehicle transmission with only one or two clutches or brakes, such a hydraulic actuator is less suitable due to the cost and power consumption of the hydraulic pump. The motor-controlled drum shift fork mechanism is realized by using a control motor, a drum, a shift fork, and a synchronizer, and has cost and power consumption lower than the hydraulic actuator. However, the motor-controlled drum shift fork mechanism has power interruption during its shifting, and thus has poor shifting smoothness. Therefore, how to reduce cost and energy consumption of a shift mechanism of the electric vehicle transmission and ensure the shifting smoothness is an urgent technical problem to be solved.

Some specific embodiments of the present invention will hereinafter be described in detail with reference to the accompanying drawings that are exemplary merely, rather than limiting the present invention. In the accompanying drawings, same or similar components or parts are denoted by same reference numerals. It should be understood by those skilled in the art that these accompanying drawings are not necessarily drawn to scale, in which:.

Exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. While the exemplary embodiments of the present invention are illustrated in the accompanying drawings, it should be understood that the present invention may be embodied in various forms and should not be construed as being limited to the embodiments set forth herein. Instead, these embodiments are provided for a complete and thorough understanding of the present invention, and can fully convey the scope of the present invention to those skilled in the art.

<FIG> is a cross-sectional view of a cone clutch <NUM> according to an embodiment of the present invention. As illustrated in <FIG>, in an embodiment, the cone clutch <NUM> includes a middle cone ring <NUM>, an inner cone ring <NUM>, and an outer ring <NUM>. The middle cone ring <NUM> has an inner ring surface and an outer ring surface, and each of the inner ring surface and the outer ring surface is a conical surface. The inner cone ring <NUM> is disposed on an inner side the middle cone ring <NUM> and has an outer ring surface. The outer ring surface of the inner cone ring <NUM> is a conical surface matching with the inner ring surface of the middle cone ring <NUM>. The outer ring <NUM> has a conical ring surface matching with the outer ring surface of the middle cone ring <NUM>. The outer ring <NUM> is movable relative to the inner cone ring <NUM> in an axial direction of the conical ring surface. The middle cone ring <NUM> and the outer ring <NUM> are connected to two to-be-engaged members, respectively. The cone clutch <NUM> is configured to engage the two to-be-engaged members by forming friction pairs in close contact between the outer ring <NUM> and the middle cone ring <NUM> and between the middle cone ring <NUM> and the inner cone ring <NUM> when the outer ring is subject to a thrust for urging the outer ring <NUM> towards the middle cone ring <NUM>. For example, the two to-be-engaged members are a shaft and a gear on the shaft.

According to the present invention, the clutch with the friction pairs having two conical ring surfaces is constructed by the middle cone ring <NUM>, the inner cone ring <NUM>, and the outer ring <NUM>. By controlling the axial movement of the outer ring <NUM>, it is possible to control engagement and disengagement of the cone clutch <NUM>, thereby engaging or disengaging the to-be-engaged member. The arrangement of two sets of friction pairs with the conical ring surfaces can reduce the control force of the clutch and enhance the torque capability of the clutch. The cone clutch <NUM> according to the embodiments is particularly suitable for a transmission with less gears and small-and-medium power.

Further, cone angles of the middle cone ring <NUM>, the inner cone ring <NUM>, and the outer ring <NUM> may be reasonably set to better amplify an axial force of the clutch. For example, if the cone angle is defined as α and the axial force of the clutch is defined as Fa, a positive pressure on the conical surface is Fn=Fa/tan(α). When the cone angle α is <NUM>°, Fn=<NUM>*Fa, which is equivalent to amplifying the axial force of the clutch by more than <NUM> times. For a cone ring with a radius of <NUM>, an axial force of <NUM> kN may generate a friction torque of <NUM>.

As illustrated in <FIG>, in an embodiment, the cone clutch <NUM> further includes a reset spring <NUM>. An end of the reset ring <NUM> is fixed, and the other end of the reset ring <NUM> is connected to the outer ring <NUM>. The reset spring <NUM> is configured to automatically reset the outer ring <NUM>. That is, when a force for urging the outer ring <NUM> towards the middle cone ring <NUM> is removed on the outer ring <NUM>, by the reset spring <NUM>, the outer ring <NUM> is restored back to its original state in which the outer ring <NUM> is not engaged with the middle cone ring <NUM>.

The present invention further provides a transmission. <FIG> is a cross-sectional view of a transmission according to an embodiment of the present invention. As illustrated in <FIG>, in an embodiment, the transmission includes a rotary shaft, a target gear, and the cone clutch <NUM> according to any one of the above embodiments. The target gear is sleeved over the rotary shaft and rotatable relative to the rotary shaft. The cone clutch <NUM> is configured to engage or disengage the rotary shaft and the target gear. That is, the rotary shaft and the target gear are the two to-be-engaged members as described above. The rotary shaft herein may be any one of an input shaft <NUM>, an intermediate shaft, and/or a transmission output shaft <NUM>, or a combination thereof, as long as the rotary shaft is a shaft for which the clutch is required.

According to the embodiments, the transmission includes two clutches with friction pairs having conical ring surfaces. By controlling the axial movement of the outer ring <NUM>, it is possible to control the engagement and disengagement of the cone clutch <NUM>, thereby engaging or disengaging the to-be-engaged members. The arrangement of two sets of friction pairs with the conical ring surfaces can reduce the control force of the clutch and enhance the torque capability of the clutch.

In an embodiment, the target gear is disposed at the rotary shaft through a support bearing <NUM>, which enables the target gear to rotate relative to the rotary shaft.

As illustrated in <FIG>, the transmission further includes a gear coupling disc <NUM>. The gear coupling disc <NUM> is fixedly connected to the target gear. The middle cone ring <NUM> is connected to the gear coupling disc <NUM> through a latch in an anti-relative rotation manner, and is slidable axially relative to the gear coupling disc <NUM>. The inner ring <NUM> is connected to the outer ring <NUM> through a latch in an anti-relative rotation manner. An end of the inner ring <NUM> abuts against the gear coupling disc <NUM> to avoid an axial movement of the inner ring <NUM> when the clutch is engaged. The outer ring <NUM> is sleeved over the rotary shaft, and connected to the rotary shaft in an anti-relative rotation manner. That is, the cone clutch <NUM> is interposed between the rotary shaft and the target gear. With this arrangement, the rotary shaft rotates synchronously with the outer ring <NUM>. When the cone clutch <NUM> is engaged, the rotary shaft can synchronously drive the target gear to rotate through the cone clutch <NUM>.

In an embodiment, a latch is disposed on a side of the middle cone ring <NUM> close to the gear coupling disc <NUM>, and the latch protrudes in an axial direction of the middle cone ring <NUM>. A first groove is formed at the gear coupling disc <NUM>, and the latch is engaged into the first groove. Relative rotation between the middle conical ring <NUM> and the gear coupling disc <NUM> can be avoided by the arrangement of the latch and the first groove.

In an embodiment, the outer ring <NUM> is connected to the rotary shaft through a spline key <NUM>, thus avoid a relative rotation therebetween. Meanwhile, the outer ring <NUM> may also be movable axially relative to the rotary shaft.

Further, in an embodiment, the cone clutch <NUM> includes a reset spring <NUM>. In this case, the transmission further includes a retainer ring <NUM> sleeved over the rotary shaft. The retainer ring <NUM> has a side in contact with the target gear and another side abutting against the reset spring <NUM>. The retainer ring <NUM> is configured to restrict an axial displacement of the target gear, and further provides an abutting surface for an end of the reset spring <NUM>. The cone clutch <NUM> can automatically be restored by the arrangement of the reset spring <NUM>.

Further, in an embodiment, as illustrated in <FIG>, the transmission further includes a circlip <NUM> sleeved over the rotary shaft and located at a side of the outer ring <NUM> away from the reset spring <NUM>. The circlip <NUM> is configured to restrict an axial displacement of the outer ring <NUM>.

<FIG> is a partially enlarged view at part A illustrated in <FIG>. As illustrated in <FIG> and <FIG>, in an embodiment, the transmission further includes an actuator. The actuator includes a motor <NUM>, a second gear <NUM>, a nut <NUM>, and a screw <NUM>. A first gear <NUM> is disposed on an output shaft of the motor <NUM>. The first gear <NUM> may be a gear sleeved over on the output shaft of the motor <NUM> or a gear machined on the output shaft of the motor <NUM>. The second gear <NUM> is meshed with the first gear <NUM>. The second gear <NUM> is sleeved over an outer surface of the nut <NUM>. The screw <NUM> forms a screw pair with an inner wall of the nut <NUM>. The screw <NUM> is fixedly connected to a housing of the transmission to enable the nut <NUM> to be axially displaced to generate a thrust directly or indirectly acting on the outer ring <NUM> when the second gear <NUM> and the nut <NUM> are driven by the motor <NUM> to rotate relative to the screw <NUM>. Optionally, a speed ratio of the first gear <NUM> to the second gear <NUM> is any value from <NUM> to <NUM>, such as <NUM>, <NUM>, or <NUM>. When the speed ratio of the first gear <NUM> to the second gear <NUM> is <NUM>, an output torque of <NUM> of the motor <NUM> is sufficient to generate an axial force of <NUM> kN or more for the engagement of the clutch.

When the torque is output from the motor <NUM>, power is transmitted to the nut <NUM> through the gear pair. As the screw <NUM> is fixed, the nut <NUM> then rotates relative to the screw <NUM> and generates an axial displacement, thereby urging the cone clutch <NUM> for the engagement or the disengagement. Certainly, in other embodiments, the nut <NUM> may also be fixed, and the screw <NUM> is driven by the motor <NUM> through the gear pair, which is also capable of outputting an axial thrust.

According to this embodiment, the transmission further includes the actuator, which is driven by the gear pair and the screw pair. Since a driving force may be amplified by the gear pair, the screw pair, and the friction pairs with the conical surfaces, the engagement of the cone clutch <NUM> may be controlled by means of a small motor <NUM>. For example, a driving torque of <NUM> may be converted into an axial force of <NUM> N by means of one screw pair. A simple pair of gear reducers may amplify the output torque of the motor <NUM> by a factor of ten or more. A small motor <NUM> with two hundred watts may transmit a torque of <NUM> by means of a simple gear reducer, a pair of screw pairs, and two friction conical surfaces, thereby satisfying requirement for driving power of a general electric vehicle. As a result, a motor <NUM> with an operating torque of smaller than <NUM> is enough to drive the cone clutch <NUM> of <NUM>.

Further, since the screw pair between the nut <NUM> and the screw <NUM> is self-locking, it is possible to lock the screw pair in an engagement position after the cone clutch <NUM> is engaged, at which point the motor <NUM> may be disconnected and no more electrical energy is consumed. That is, compared to an existing hydraulic actuator, the actuator according to this embodiment can save power consumption, thereby improving the efficiency of the transmission.

Further, a conventional automotive transmission clutch is generally a multi-plate and wet clutch, and its actuator is an electro-hydraulically controlled hydraulic cylinder. Such the actuator includes a hydraulic pump, a hydraulic cylinder, a proportional pressure solenoid valve, and a valve plate. Therefore, only the motor <NUM> is required for a power source of the actuator in this embodiment, thereby lowering manufacturing cost of the actuator.

In other embodiments, the screw pair formed by the nut <NUM> and the screw <NUM> in the actuator may be replaced with a ball screw (not shown), thereby reducing frictional resistance and saving control power.

Further, in an embodiment, the transmission further includes a first buffer assembly disposed between the nut <NUM> of the actuator and the outer ring <NUM>. The first buffer assembly includes a radial positioning ring <NUM>, a first thrust bearing <NUM>, and a first spring diaphragm <NUM> that sequentially abut against each other. A side of the radial positioning ring <NUM> away from the first thrust bearing <NUM> abuts against the nut <NUM> to restrict a radial displacement of the first thrust bearing <NUM>. A side of the first spring diaphragm <NUM> away from the first thrust bearing <NUM> abuts against the outer ring <NUM> of the cone clutch <NUM> at a side where the first spring diaphragm <NUM> is located. The first spring diaphragm <NUM> is disposed between the first thrust bearing <NUM> and the outer ring <NUM>, and serves to buffer an impact of the nut <NUM> to avoid an impact of the clutch during its engagement.

In an embodiment, a plurality of cone clutches <NUM>, a plurality of actuators, and a plurality of first buffer assemblies are provided and are same in quantity. The plurality of cone clutches <NUM> is arranged in one-to-one correspondence with the plurality of actuators and the plurality of first buffer assemblies. That is, only one actuator can drive the corresponding one of the plurality of cone clutches, with one first buffer assembly interposed therebetween.

As illustrated in <FIG>, in an embodiment, two cone clutches are provided. The outer rings <NUM> of the two cone clutches <NUM> are located at two sides of the nut <NUM>, respectively. The motor <NUM> is configured to output forward torque and backward torque to enable the two cone clutches <NUM> to share one actuator.

In another embodiment, as illustrated in <FIG>, the transmission further includes a first buffer assembly, a second buffer assembly, and an anti-loosening spring <NUM>. The first buffer assembly and the second buffer assembly are located at two sides of the nut <NUM> in an axial direction of the nut <NUM>, respectively. The anti-loosening spring <NUM> is disposed in an axial through hole of the nut <NUM>, and has two ends respectively abutting against the first buffer assembly and the second buffer assembly.

In an embodiment, as illustrated in <FIG>, the first buffer assembly includes a radial positioning ring <NUM>, a first thrust bearing <NUM>, and a first spring diaphragm <NUM> that sequentially abut against each other. A side of the radial positioning ring <NUM> away from the first thrust bearing <NUM> abuts against the nut <NUM> and is connected to an end of the anti-loosening spring <NUM>, to restrict a radial displacement of the first thrust bearing <NUM>. A side of the first spring diaphragm <NUM> away from the first thrust bearing <NUM> abuts against the outer ring <NUM> of the cone clutch <NUM> at a side where the first spring diaphragm <NUM> is located. In an embodiment, the radial positioning ring <NUM> is substantially in a "Z" shape and has two radial surfaces that respectively abut against the first thrust bearing <NUM> and the nut <NUM>, thereby radially positioning the first thrust bearing <NUM>.

In an embodiment, as illustrated in <FIG>, the second buffer assembly includes a second thrust bearing <NUM>, a gasket <NUM>, a transition ring <NUM>, a third thrust bearing <NUM>, and a second spring diaphragm <NUM> that sequentially abut against each other in an axial direction of the rotary shaft. An end surface of the second thrust bearing <NUM> away from the gasket <NUM> is connected to the anti-loosening spring <NUM>. A side of the second spring diaphragm <NUM> away from the transition ring <NUM> abuts against the outer ring <NUM> of the cone clutch <NUM> at a side where the second spring diaphragm <NUM> is located.

The anti-loosening spring is configured to allow a predetermined pre-tightening force to be always generated between various components of the second buffer assembly, thus reducing noise during the shifting.

Further, in an embodiment, as illustrated in <FIG>, a second groove <NUM> is formed at an end surface of the nut <NUM> away from the first buffer assembly. The second groove <NUM> radially penetrates an outer ring surface of the nut <NUM>. Both the second thrust bearing <NUM> and the gasket <NUM> are disposed within the second groove <NUM>, and are engaged with a bottom surface of the second groove <NUM> in a radial direction of the second groove <NUM>, thereby restricting radial displacements of the second thrust bearing <NUM> and the gasket <NUM>.

As illustrated in <FIG>, further, in an embodiment, a first boss <NUM> and a second boss <NUM> are disposed on two sides of the transition ring <NUM> in an axial direction of the transition ring <NUM>, respectively. The first boss <NUM> is engaged with a circumferential surface of the gasket <NUM> to restrict a radial displacement of the transition ring <NUM>. The second boss <NUM> is engaged with a circumferential surface of the third thrust bearing <NUM> to restrict a radial displacement of the third thrust bearing <NUM>.

In this embodiment, the radial positioning is based on the nut <NUM> to sequentially restrict the radial displacement of each of the second thrust bearing <NUM>, the gasket <NUM>, the transition ring <NUM>, and the third thrust bearing <NUM>. In other embodiments, other radial positioning manners may be used, for example, by providing radial engagement features on the screw <NUM> and the transition ring <NUM>, using the screw <NUM> to radially position the transition ring <NUM>, which in turn positions the second thrust bearing <NUM> and the third thrust bearing <NUM>.

<FIG> is a cross-sectional view taking along line B-B illustrated in <FIG>. As illustrated in <FIG> and <FIG>, in this embodiment, the screw <NUM> has a plurality of connection arms <NUM>. Each of the plurality of connection arms <NUM> is fixedly connected to the housing of the transmission.

Further, in an embodiment, the plurality of connection arms <NUM> is evenly arranged in a circumferential direction of the screw <NUM>. Each of the plurality of connection arms <NUM> protrudes from the screw <NUM> in a radial direction of the screw <NUM>. Accordingly, it is necessary for the transition ring <NUM> to have a plurality of radial through groove <NUM> to allow each of the connection arms to pass therethrough.

It should be noted that, due to assembly requirement, the through groove <NUM> should also perpetrate an axial side of the transition ring <NUM> to facilitate an axial assembly between the transition ring <NUM> and the screw <NUM>. In this case, a plurality of grooves is formed at an end surface of the transition ring <NUM> in an axial direction of the transition ring <NUM>. The plurality of grooves may be covered with a gasket <NUM> disposed on this end surface, thereby facilitating abutment of the thrust bearing (the second thrust bearing <NUM> in the embodiment of <FIG>) to realized more stable force transmission.

<FIG> is a schematic principle view of a transmission according to an embodiment of the present invention. <FIG> is a schematic view of a radial arrangement of the transmission of <FIG>. <FIG> is a schematic principle view of a transmission according to another embodiment of the present invention. As can be seen in <FIG> and <FIG>, in the present invention, it is possible for one actuator to control one cone clutch <NUM> alone (see <FIG>), and it is also possible for one actuator to provide two adjacent cone clutches <NUM> with braking power simultaneously (see <FIG>). For example, in some embodiments, two cone clutches <NUM>, two actuators, and two first buffer assemblies are provided, and the two cone clutch <NUM> are arranged in one-to-one correspondence with the two actuators and the two first buffer assemblies. Thus, it is possible to control one cone clutch <NUM> by one actuator individually. When one actuator is shared by the two cone clutches <NUM>, there is a short (tens of milliseconds) power interruption during the shifting, which is not normally felt. When one cone clutch <NUM> is controlled by one actuator alone, an unpowered interruption can be achieved, and thus the shifting is smoother.

In an embodiment, the rotary shaft includes a transmission input shaft <NUM> and/or a transmission output shaft <NUM>. In other words, it is possible to provide one cone clutch <NUM> on the transmission input shaft <NUM> (see <FIG>) or on the transmission output shaft <NUM>, or to provide the cone clutch <NUM> on each of the input shaft <NUM> and the transmission output shaft <NUM> (see <FIG>). The cone clutch may be arranged as required. For example, separate cone clutches <NUM> are provided for different rotary shafts depending on a space arrangement requirement. Certainly, for some transmissions having an intermediate shaft, the cone clutch <NUM> may also be disposed on the intermediate shaft. At least two sets of variable gears are provided on the transmission input shaft <NUM> and the transmission output shaft <NUM>, and the target gears are all driving gears on the transmission input shaft <NUM> or all driven gears on the transmission output shaft <NUM>; or the target gears are at least one driving gear on the transmission input shaft <NUM> and a driven gear, in no mesh with the at least one driving gear, on the transmission output shaft <NUM>.

In an embodiment, as illustrated in <FIG> or <FIG>, the transmission input shaft <NUM> is connected to an output shaft of a prime motor <NUM>, for example, through the spline key <NUM>. Two ends of the transmission input shaft <NUM> may be supported on a front housing <NUM> and a rear housing <NUM> by a first bearing <NUM> and a second bearing <NUM>, respectively. Two sets of variable gears are provided on the transmission input shaft <NUM> and the transmission output shaft <NUM>. An output gear <NUM> is further provided on the transmission output shaft <NUM> and is connected to a differential <NUM>. In some embodiments, a first driving gear <NUM> and a second driving gear <NUM> are provided on the transmission input shaft <NUM>. Moreover, a first driven gear <NUM> and a second driven gear <NUM> are provided on the transmission output shaft <NUM>, and are meshed with the first driving gear <NUM> and the second driving gear <NUM>, respectively. The first driving gear <NUM> and the first driven gear are formed into a low-speed gear pair, and the second driving gear <NUM> and the second driven gear are formed into a high-speed gear pair. One cone clutch <NUM> is connected in series between the first driving gear <NUM> and the transmission input shaft <NUM>, and one cone clutch <NUM> is connected in series between the second driving gear <NUM> and the transmission input shaft <NUM>. By engagement or disengagement of the two cone clutches <NUM>, power from the transmission input shaft <NUM> is transmitted to the first driving gear <NUM> or the second driving gear <NUM>. A common actuator is provided between the two cone clutches <NUM>. The output gear <NUM> is further provided on the transmission output shaft <NUM>. The output gear <NUM> (equivalent to a driving gear of the differential <NUM>) is meshed with a differential gear <NUM> of the differential <NUM> to transmit the power to wheels through the differential <NUM> and a half shaft. Such a two-speed transmission is particularly suitably used as a transmission for an electric vehicles of not too great power.

Claim 1:
A cone clutch (<NUM>), comprising:
a middle cone ring (<NUM>) having an inner ring surface and an outer ring surface, each of the inner ring surface and the outer ring surface being a conical surface;
an inner cone ring (<NUM>) disposed on an inner side of the middle cone ring (<NUM>) and having an outer ring surface, the outer ring surface of the inner cone ring (<NUM>) being a conical surface matching with the inner ring surface of the middle cone ring (<NUM>); and
an outer ring (<NUM>) having a conical ring surface matching with the outer ring surface of the middle cone ring (<NUM>), wherein:
the outer ring (<NUM>) is movable relative to the inner cone ring (<NUM>) in an axial direction of the conical ring surface;
the middle cone ring (<NUM>) and the outer ring (<NUM>) are connected to two to-be-engaged members, respectively; and
the cone clutch (<NUM>) is configured to engage the two to-be-engaged members by forming friction pairs in close contact between the outer ring (<NUM>) and the middle cone ring (<NUM>) and between the middle cone ring (<NUM>) and the inner cone ring (<NUM>) when the outer ring (<NUM>) is subject to a thrust for urging the outer ring (<NUM>) towards the middle cone ring (<NUM>),
characterised in that the cone clutch (<NUM>) further comprises a reset spring (<NUM>), an end of the reset spring (<NUM>) being fixed, and another end of the reset spring (<NUM>) being connected to the outer ring (<NUM>).