Transmission for vehicle

A transmission for a vehicle may include a first input shaft continuously receiving power from an engine, a second input shaft selectively receiving power from the engine, a first output shaft and a second output shaft disposed in parallel with the first input shaft and the second input shaft, an initial shift device including a plurality of driving gears on the second input shaft, a plurality of driven gears on the first output shaft and the second output shaft for making a series of gear shift ranges, and a plurality of synchronizers selectively making a predetermined gear shift range of the gear shift ranges made by the driving gears and the driven gears, a duplicate shift device configured to make duplicate gear shift ranges, a first output gear disposed on the first output shaft to draw power from the first output shaft, and a one-way clutch.

CROSS REFERENCE TO RELATED APPLICATION

The present application claims priority to Korean Patent Application Number 10-2015-0015296 filed Jan. 30, 2015, the entire contents of which is incorporated herein for all purposes by this reference.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a transmission for a vehicle. More particularly, the present invention relates to the configuration of a transmission that can automatically shift, based on a synchro-mesh type shifting mechanism that is generally used for manual transmissions.

Description of Related Art

In the related art, an Automated Manual Transmission (AMT) includes a clutch actuator for connecting/disconnecting a clutch and a shift actuator for engaging shift gears and disengaging desired shift gears and can automatically shift by operating the clutch actuator and the shift actuator in accordance with the driving states of a vehicle.

However, according to the AMT, it is required to cut torque from the clutch actuator to the AMT in order to disengage a previous shift gear and engage a new desired shift gear by operating the shift actuator, so interruption of torque that is supposed to be supplied to driving wheels from an engine is generated, which interferes with smooth shifting and deteriorates riding comfort.

BRIEF SUMMARY

Various aspects of the present invention are directed to providing a transmission for a vehicle that can prevent deterioration of smooth shifting and riding comfort due to torque interruption, can be more conveniently mounted on a vehicle due to a relatively simple and compact configuration, and can contribute to improving fuel efficiency.

According to various aspects of the present invention, a transmission for a vehicle may include a first input shaft continuously receiving power from an engine, a second input shaft selectively receiving power from the engine, a first output shaft and a second output shaft disposed in parallel with the first input shaft and the second input shaft, an initial shift device including a plurality of driving gears on the second input shaft, a plurality of driven gears on the first output shaft and the second output shaft for making a series of gear shift ranges by engaging with the driving gears on the second input shaft, respectively, and a plurality of synchronizers selectively making a predetermined gear shift range of the gear shift ranges made by the driving gears and the driven gears, a duplicate shift device configured to make duplicate gear shift ranges, which have a gear ratio the same as the gear ratio of one or more gear shift ranges of the series of gear shift ranges made by the initial shift device, between the first input shaft and the first output shaft, a first output gear disposed on the first output shaft to draw power from the first output shaft, and a one-way clutch disposed in a power transmission line from the engine to the first output gear through the duplicate shift device to transmit power from the engine only to the first output gear.

The input shaft may be a hollow shaft fitted on the first input shaft and connected to a clutch to selectively receive power from the engine.

The duplicate shift device may achieve a plurality of duplicate gear shift ranges sequentially from a gear shift range having a largest gear ratio of a series of gear shift ranges made among the second input shaft, the first output shaft, and the second output shaft.

When the series of gear shift ranges that are made by the initial shift device includes at least four or more gear shift ranges sequentially from a first gear shift range having a largest gear ratio, the duplicate shift device may be configured to make a first duplicate shift range having a same gear ratio as a gear ratio of the first gear shift range and a second duplicate shift range having a same gear ratio as a gear ratio of the second gear shift range.

The duplicate shift device may include a first duplicate driving gear disposed on the first input shaft and a first duplicate driven gear disposed on the first output shaft in order to make the first duplicate gear shift range, a second-range duplicate driving gear disposed on the first input shaft and a second-range duplicate driven gear disposed on the first output shaft in order to make the second duplicate gear shift range, and a1&2duplicate synchronizer for selecting the first duplicate gear shift range or the second duplicate gear shift range from a neutral range.

The first gear shift range and the fourth gear shift range may be made between the second input shaft and the first output shaft by the initial shift device, and the second gear shift range and the third gear shift range may be made between the second input shaft and the second output shaft by the initial shift device.

One or more gear shift ranges having a gear ratio smaller than the gear ratio of the fourth gear shift range may be made between the second input shaft and the second output shaft.

A receive gear for receiving power from the first output shaft may be disposed on the second output shaft, a medium gear may be disposed between the first output gear and the receive gear to transmit power from the first output gear to the receive gear, and a second output gear transferring power from the second output shaft to a differential may be integrally disposed on the second output shaft.

The one-way clutch may be disposed between the first output shaft and the first output gear so that power is transmitted only to the first output gear from the first output shaft.

In the first duplicate driven gear and the second duplicate driven gear, a shift gear and a clutch gear may be separated, and the one-way clutch may be disposed between the shift gear and the clutch gear to transmit power only to the clutch gear from the shift gear.

A hub of the1&2duplicate synchronizer may include an inner hub fitted on the first output shaft and an outer hub disposed outside the inner hub to rotate relative to the inner hub and supporting a sleeve, and the one-way clutch may be disposed between the outer hub and the inner hub to transmit power only to the inner hub from the outer hub.

The one-way clutch may be disposed between a flywheel and the first input shaft to transmit power only to the first input shaft from the flywheel of the engine.

A second output gear for drawing power from the second output shaft may be disposed on the second output shaft, and the first output gear of the first output shaft and the second output gear of the second output shaft may be engaged with a ring gear of a differential to transfer power to the differential.

According to the present invention, it is possible to achieve a transmission for a vehicle that can prevent deterioration of smooth shifting and riding comfort due to torque interruption and which has a relatively simple and compact configuration, thus the transmission can be easily mounted in a vehicle and can contribute to improving fuel efficiency.

DETAILED DESCRIPTION

Referring toFIG. 10toFIG. 15, embodiments of a transmission for a vehicle according to the present invention, in common, include a first input shaft IN1that continuously receives power from an engine E, a second input shaft IN2that selectively receives power from the engine E, a first output shaft OUT1and a second output shaft OUT2that are disposed in parallel with the first input shaft IN1and the second input shaft IN2, an initial shift device ISU that includes a plurality of driving gears on the second input shaft IN2, a plurality of driven gears on the first output shaft OUT1and the second output shaft OUT2for making a series of gear shift ranges by engaging with the driving gears on the second input shaft IN2, respectively, and a plurality of synchronizers selectively making a predetermined gear shift range of the gear shift ranges made by the driving gears and the driven gears; a duplicate shift device DSU that makes a duplicate gear shift range, which has a gear ratio the same as the gear ratio of one or more gear shift ranges of the series of gear shift ranges made by the initial shift device, between the first input shaft IN1and the first output shaft OUT1, a first output gear OT1disposed on the first output shaft OUT1to draw power from the first output shaft OUT1, and a one-way clutch OWC that is disposed in the power transmission line from the engine E to the first output gear OT1through the duplicate shift device DSU to transmit power from the engine E only to the first output gear OT1.

That is, in order to achieve the series of gear shift range for a vehicle, the initial shift device ISU is provided and some the gear shift ranges made by the initial shift device ISU are made in duplicate by the duplicate shift device DSU, so power transmitted from the engine E to the first output gear OT1through the duplicate shift device DSU passes through the one-way clutch in the transmission line.

The input shaft IN2is a hollow shaft fitted on the first input shaft IN1and connected with a clutch CL to selectively receive power from the engine E.

The duplicate shift device DSU can achieve a plurality of duplicate gear shift ranges sequentially from the gear shift range having the largest gear ratio of the series of gear shift ranges made among the second input shaft IN2, the first output shaft OUT1, and the second output shaft OUT2.

That is, for example, when the initial shift device ISU makes six forward gear shift ranges from a first gear shift range having the largest gear ratio to a sixth gear shift range having the smallest gear ratio, the duplicate shift device DSU may make gear ratios the same as those of the first gear shift range having the largest gear ratio and the second gear shift range having the next gear ratio; may make gear ratios the same as those of the first gear shift range, the second gear shift range, and the third gear shift range; may make gear ratios the same as those of the first gear shift range to the fourth gear shift range; or may make gear ratios the same as those of the first gear shift range to the fifth gear shift range.

This is because the duplicate gear shift ranges made by the duplicate shift device DSU plays an important part in preventing torque interruption that is generated in shifting and the torque interruption influences smooth shifting and riding comfort when a vehicle is driven at a low speed with a relatively large gear ratio.

That is, for example, if a vehicle has six forward gear shift ranges, the ranges where there is a problem with smooth shifting or riding comfort due to torque interruption while the vehicle is driven are the first gear shift range to the third gear shift range, but torque interruption does not influence smooth shifting or riding comfort at higher gear shift ranges, because the speed and the inertia of the vehicle are substantially high and large at those ranges. Accordingly, the duplicate shift device DSU makes duplicate gear shift ranges having the same gear ratios as those of low gear shift ranges in order to improve torque interruption that may be generated at the first gear shift range to the third gear shift range.

Obviously, the number of duplicate gear shift ranges that are made by the duplicate shift device DSU may be increased or decreased in accordance with the design concept of a vehicle to be manufactured, but relatively high gear shift ranges having small gear ratios are increased or decreased without changing low gear shift ranges having relatively large gear ratios.

Accordingly, when a series of gear shift ranges that are made by the initial shift device ISU includes at least fourth or more gear shift ranges sequentially from a first gear shift range having the largest gear ratio, the duplicate shift device DSU is configured to make a first duplicate shift range having the same gear ratio as that of the first gear shift range and a second duplicate shift range having the same gear ratio as that of the second gear shift range.

In the various embodiments shown inFIG. 1, andFIG. 10toFIG. 15, the duplicate shift device DSU includes a first duplicate driving gear1DD disposed on the first input shaft IN1and a first duplicate driven gear1DP disposed on the first output shaft OUT1in order to make the first duplicate gear shift range, a second duplicate driving gear2DD disposed on the first input shaft IN1and a second duplicate driven gear2DP disposed on the first output shaft OUT1in order to make the second duplicate gear shift range, and a1&2duplicate synchronizer1&2DS for selecting the first duplicate gear shift range or the second duplicate gear shift range from a neutral range.

The first gear shift range and the fourth gear shift range are made between the second input shaft IN2and the first output shaft OUT1by the initial shift device ISU.

The second gear shift range and the third gear shift range are made between the second input shaft IN2and the second output shaft OUT2by the initial shift device ISU.

That is, the first gear shift range and the fourth gear shift range are made between the second input shaft IN2and the first output shaft OUT1, and the second gear shift range and the third gear shift range are made between the second input shaft IN2and the second output shaft OUT2.

At least one gear shift range having a gear ratio smaller than that of the fourth gear shift range is further made between the second input shaft IN2and the second output shaft OUT2, and in the various embodiments, a fifth gear shift range and a sixth gear shift range are further made.

The fifth gear shift range is achieved by the driving gear for making the first gear shift range and the sixth gear shift range is achieved by the driving gear for making the fourth gear shift range, so the transmission can be made short and compact.

For reference, the gear disposed on the first output shaft OUT1to make the first gear shift range is referred to as a first driven gear, the gear disposed on the first output shaft OUT1to make the fourth gear shift range is referred to as a fourth driven gear, and the synchronizer for selectively connecting the first driven gear1P or the fourth driven gear4P to the first output shaft OUT1is referred to as a1&4synchronizer1&4S.

Further, the gear disposed on the second output shaft OUT2to make the second gear shift range is referred to as a second driven gear2P, the gear disposed on the second output shaft OUT2to make the third gear shift range is referred to as a third driven gear3P, and the synchronizer for selectively connecting the second driven gear2P or the third driven gear3P to the second output shaft OUT2is referred to as a2&3synchronizer2&3S.

Further, the gear disposed on the second output shaft OUT2to make the fifth gear shift range is referred to as a fifth driven gear5P, the gear disposed on the second output shaft OUT2to make the sixth gear shift range is referred to as a sixth driven gear6P, and the synchronizer for selectively connecting the fifth driven gear5P or the sixth driven gear6P to the second output shaft OUT2is referred to as a5&6synchronizer5&6S.

This configuration is applied in the same way to all of the various embodiments shown inFIGS. 1, and 10 to 15, and other differences will be described below.

In various embodiments shown inFIG. 1, various embodiments shown inFIG. 10, various embodiments shown inFIG. 11, and various embodiments shown inFIG. 12, a receive gear RCV for receiving power from the first output shaft OUT1is disposed on the second output shaft OUT2, a medium gear MG is disposed between the first output gear OT1and the receive gear RCV to transmit the power from the first output gear OT1to the receive gear RCV, and a second output gear OT2transferring power from the second output shaft OUT2to a differential DF is integrally disposed on the second output shaft OUT2.

Accordingly, the power from the first output shaft OUT1is transmitted to the second output shaft OUT2through the first output gear OT1, the medium gear MG, and the receive gear RCV and then transmitted to a ring gear R of the differential through the second output gear OT2.

In the various embodiments shown inFIG. 1, the one-way clutch OWC is disposed between the first output shaft OUT1and the first output gear OT1so that power is transmitted only to the first output gear OT1from the first output shaft OUT1.

That is, power is transmitted only by the one-way clutch OWC between the first output shaft OUT1and the first output gear OT1in the power transmission line from the engine E to the first output gear OT1through the duplicate shift device DSU and the first output shaft OUT1, so power is not transmitted to the first output shaft OUT1from the first output gear OT1.

Obviously, in this configuration, the power transmitted to the first output shaft OUT1through the initial shift device ISU can also be transferred to the differential DF through the first output gear OT1only through the one-way clutch OWC.

In the various embodiments shown inFIG. 10, in the first duplicate driven gear1DP and the second duplicate driven gear2DP, a shift gear SG and a clutch gear CG are separated, and a one-way clutch OWC is disposed between the shift gear SG and the clutch gear CG to transmit power only to the clutch gear CG from the shift gear SG.

For reference, inFIG. 10, a hub H and a sleeve SL are indicated at the right side of the clutch gear CG.

Accordingly, in the various embodiments shown inFIG. 10, in the power transmission line from the engine E to the first output gear OT1through the duplicate shift device DSU, power is transmitted through the one-way clutch OWC between shift gears SG and the clutch gears CG of the duplicate shift device DSU.

For example, power transmitted through the first duplicate driving gear from the first input shaft IN1is transmitted to the shift gear SG of the first duplicate driven gear1DP and then transmitted to the clutch gear CG through the one-way clutch OWC. If the1&2duplicate synchronizer1&2DS is engaged with the clutch gear CG of the first duplicate driven gear1DP, power passing through the one-way clutch OWC is transmitted to the first output shaft OUT1and the first output gear OT1through the1&2duplicate synchronizer1&2DS.

Obviously, in this case, the first output gear OT1is integrated with the first output shaft OUT1such that it is not rotated.

In the various embodiments shown inFIG. 11, a hub of the1&2duplicate synchronizer1&2DS is composed of an inner hub IH fitted on the first output shaft OUT1and an outer hub OH disposed outside the inner hub IH to rotate relatively to the inner hub IH and supporting a sleeve SL, and a one-way clutch OWC is disposed between the outer hub OH and the inner hub IH to transmit power only to the inner hub IH from the outer hub OH.

For example, when the sleeve of the1&2duplicate synchronizer1&2DS is engaged with a first duplicate driven gear1DP, power from the engine E is transmitted to the outer hub OH through the sleeve, further transmitted to the inner hub IH through the one-way clutch OWC, and then reaches the first output shaft OUT1and the first output gear OT1.

In the various embodiments shown inFIG. 12, a one-way clutch OWC is disposed between a flywheel FL and a first input shaft IN1to transmit power only to the first input shaft IN1from the flywheel FL of the engine E.

As can be seen in common from the various embodiments ofFIG. 1toFIG. 12, the one-way clutch OWC transmits power from the engine E to the differential DF through the duplicate shift device DSU, not in the opposite direction, so interlock between the power transmitted from the engine E to the differential DF through the duplicate shift device DSU and the power transmitted to the differential DF through the initial shift device ISU is structurally prevented and power can be transmitted through the duplicate shift device DSU only when power can be transmitted to the differential DF through the duplicate shift device DSU without interlock of the power.

Various embodiments shown inFIG. 13, various embodiments shown inFIG. 14, and various embodiments shown inFIG. 15are different from the various embodiments shown inFIG. 1toFIG. 12. In these various embodiments, a first output gear OT1is integrated with a first output shaft OUT1, a second output gear OT2for drawing power from a second output shaft OUT2is disposed on the second output shaft OUT2, and a first output gear OT1of the first output shaft OUT1and a second output gear OT2of the second output shaft OUT2are engaged with a ring gear R of a differential DF to transfer power to the differential DF, so there are no medium gear MG and receive gear RCV.

In the various embodiments shown inFIG. 13, a one-way clutch OWC is installed in the same way as the various embodiments shown inFIG. 10, a shift gear SG and a clutch gear CG are separated in the first duplicate driven gear1DP and the second duplicate driven gear2DP, and the one-way clutch OWC is disposed between the shift gear SG and the clutch gear CG to transmit power only to the clutch gear CG from the shift gear SG.

In the various embodiments shown inFIG. 14, a one-way clutch OWC is installed in the same way as the various embodiments shown inFIG. 11, a hub of the1&2duplicate synchronizer1&2DS is composed of an inner hub IH fitted on the first output shaft OUT1and an outer hub OH disposed outside the inner hub IH to rotate relatively to the inner hub IH and supporting a sleeve SL, and a one-way clutch OWC is disposed between the outer hub OH and the inner hub IH to transmit power only to the inner hub IH from the outer hub OH.

In the various embodiments shown inFIG. 15, a one-way clutch OWC is disposed, in the same way as the various embodiments shown inFIG. 12, between a flywheel FL and a first input shaft IN1to transmit power only to the first input shaft IN1from the flywheel FL of the engine E.

The operation is described hereafter with reference toFIG. 2toFIG. 9based on the various embodiments shown inFIG. 1.

FIG. 2shows a case when a first gear shift range is selected to start a vehicle at an N-range for neutral. In this state, the engine E has been started, so the first input shaft IN1directly connected to the engine E is rotated but the1&2duplicate synchronizer1&2DS is in a neutral state, so power is not transmitted to the first output shaft OUT1. Further, the clutch CL is not engaged, so the power from the engine E is also not supplied to the second input shaft IN2too. Accordingly, the engine E can be started in this state.

FIG. 3shows a case when a vehicle is started with the clutch CL engaged from the state ofFIG. 2, in which the power from the engine E is transmitted to the first driven gear1P through the second input shaft IN2and is transmitted to the first output shaft OUT1through the1&4synchronizer1&4S, so power is transmitted with the first gear shift range.

The power from the first output shaft OUT1passes through the one-way clutch OWC and is then transmitted to the second output shaft OUT2through the first output gear OT1, the medium gear MG, and the receive gear RCV, and the power from the second output shaft OUT2is transmitted to the differential DF by the second output gear OT2.

FIG. 4shows a state that can be achieved after or simultaneously with the state ofFIG. 3, in which the first duplicate driven gear1DP is connected to the first output shaft OUT1by the1&2duplicate synchronizer1&2DS, so power of the engine E transmitted to the first input shaft IN1is changed through the first duplicate driving gear1DD and the first duplicate driven gear1DP and then transmitted to the first output shaft OUT1.

That is, in this state, the power from the engine E is transmitted simultaneously to driving wheels through the first gear shift range by the initial shift device ISU and the first duplicate gear shift range by the duplicate shift device DSU.

FIG. 5shows a state when the1&4synchronizer1&4S is disengaged from the state ofFIG. 4to the neutral state so that power is not transmitted through the first gear shift range and the power from the engine E is transmitted to the driving wheels only through the first duplicate shift range, in which power from the first output shaft OUT1is transmitted to the first output gear OT1through the one-way clutch OWC.

Substantially, in the vehicle, the gear ratio for the first gear shift range is achieved in all of the states ofFIG. 3,FIG. 4, andFIG. 5, but the vehicle is usually driven at the first gear shift ratio in the state ofFIG. 5to prepare the next shifting to the second gear shift range.

For reference, although the clutch CL is engaged inFIG. 5, power is transmitted only through the first input shaft IN1, so the clutch CL may be disengaged after the1&2duplicate synchronizer1&2DS is engaged with the first duplicate driven gear1DP as shown inFIG. 4, so the clutch CL can be disengaged in the state ofFIG. 5.

FIG. 6shows a case for preparing for shifting to the second gear shift range from the state ofFIG. 5, in which the transmission prepares for shifting to the second gear shift ratio by connecting the second driven gear2P to the second output shaft OUT2using a2&3synchronizer2&3S, with the clutch CL disengaged. Obviously, the vehicle is driven with the gear ratio for the first gear shift range at the first duplicate gear shift range.

In order to drive the vehicle with the gear ratio for the second gear shift range by the initial shift device ISU from the state ofFIG. 6, it has only to engage the clutch CL, as inFIG. 7. That is, the power from the engine E is transmitted to the second output shaft OUT2through the second driven gear2P from the second input shaft IN2and drawn out to the differential DF with the gear ratio for the second gear shift range.

Accordingly, torque interruption is not generated in shifting to the second gear shift range from the first gear shift range, so shifting is more smoothly made and riding comfort is improved.

In this state, the first output shaft OUT1is operated by the power transmitted through the first duplicate gear shift range, but is not involved with the power transmitted through the second gear shift range by the initial shift device ISU by the one-way clutch, so interlock is not generated and the vehicle is driven with the gear ratio for the second gear shift range by the power transmitted through the second gear shift range.

FIG. 8shows a case when the second duplicate driven gear2DP is connected to the first output shaft OUT1by operating the1&2duplicate synchronizer1&2DS from the state ofFIG. 7.

In this state, the power from the engine E is transmitted to the differential DF through the second gear shift range by the initial shift device ISU and also through the second duplicate gear shift range by the duplicate shift device DSU.

FIG. 9shows a case when the2&3synchronizer2&3S is disengaged to the neutral state from the state ofFIG. 8, in which, similarly, the power from the engine E is continuously transmitted to the differential DF through the second duplicate gear shift range, so the second gear shift range is maintained.

The vehicle is usually driven at the second gear shift range in the state ofFIG. 9, and then, similarly, the third driven gear3P is connected to the second output shaft OUT2by the2&3synchronizer2&3S with the clutch CL disengaged and then the clutch CL is engaged back, thereby shifting to the third gear shift range from the second gear shift range without torque interruption.

In the various embodiments, shifting to the fourth gear shift range to the sixth gear shift range is made by disengaging the clutch CL, engaging desired gears, and the engaging back the clutch CL, in the same was as an AMT of the related art, so although torque interruption is generated, the speed and inertia of the vehicle are high, so it has little influence on smooth shifting and riding comfort.

That is, for the gear ratios where torque interruption substantially influences smooth shifting or riding comfort of a vehicle, torque interruption is prevented by making a duplicate gear shift range, and the shifting way of the related art is maintained for the next gear ratios, so it is possible to minimize the weight of the transmission and improve smooth shifting and riding comfort.

Obviously, which gear ratio torque interruption is prevented depends on the design concept of a vehicle to be manufactured, and accordingly, the number of duplicate gear shift ranges may be variably determined.

In the various embodiments ofFIG. 10toFIG. 15, shifting is made in almost the same way as the shifting in the various embodiments ofFIG. 1toFIG. 9, and the principle of the one-way clutch OWC that operates such as power is transmitted to driving wheels through the duplicate shift device DSU only when power can be transmitted through the duplicate shift device DSU without interlock between power passing through the initial shift device ISU and the power passing through the duplicate shift device DSU from the engine E is the same, so the detailed description is not provided.