JP2024034448A - Power transmission device of vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power transmission device of a vehicle having a lock-up clutch which enables simple structure and can inhibit energy consumption.

SOLUTION: A power transmission device 50 of a vehicle 10 transmits power between a pump disc 16p and a turbine disc 16t provided within a case 16c of a torque converter 16 through an oil OIL. A lock-up clutch LU directly connecting the pump disc 16p with the turbine disc 16t is provided outside the case 16c and a normally closed type. The structure can inhibit energy consumption for maintaining an engagement state of the lock-up clutch LU.

SELECTED DRAWING: Figure 1

COPYRIGHT: (C)2024,JPO&INPIT

Description

The present invention relates to a power transmission device for a vehicle equipped with a torque converter.

For example, in hybrid cars and electric cars that are equipped with an electric motor as a power source, a torque converter with a torque amplification function is installed in the power transmission path between the electric motor and the drive wheels to compensate for the lack of driving force when starting. be. Further, by controlling the lock-up clutch to be engaged in a vehicle speed range other than when the vehicle is started, a decrease in transmission efficiency in the torque converter is suppressed. However, when the lockup clutch is of a normally open type, it is necessary to continue supplying hydraulic pressure to an actuator that controls engagement and disconnection of the lockup clutch in order to maintain the engaged state of the lockup clutch. Therefore, energy continues to be consumed in the hydraulic control circuit that supplies hydraulic pressure to the actuator. Since the hybrid vehicle described in Patent Document 1 uses a normally closed type lockup clutch, it is possible to suppress energy consumption for maintaining the engaged state of the lockup clutch.

Japanese Patent Application Publication No. 2012-72855

However, in the hybrid vehicle described in Patent Document 1, a normally closed type lock-up clutch is provided in the torque converter, so the structure of the lock-up clutch is changed, such as having multiple oil passages and oil chambers. It's getting complicated.

The present invention has been made against the background of the above circumstances, and its purpose is to provide a power transmission device for a vehicle that has a lock-up clutch that enables a simple configuration and suppresses energy consumption. There is a particular thing.

The gist of the present invention is to provide a power transmission device for a vehicle equipped with a torque converter that transmits power via fluid between a pump impeller and a turbine impeller provided in a case. A lock-up clutch that directly connects the pump wheel and the turbine wheel is provided outside the case and is of a normally closed type.

According to the vehicle power transmission device of the present invention, the lock-up clutch that directly connects the pump impeller and the turbine impeller is provided outside the case and is of a normally closed type. By providing the lockup clutch outside the case of the torque converter, the lockup clutch can have a simple configuration. Further, since the lock-up clutch is of a normally closed type, the engaged state of the lock-up clutch is maintained even without applying a control signal during normal driving in the coupling range of the torque converter. Thereby, energy consumption for maintaining the engaged state of the lock-up clutch can be suppressed.

FIG. 1 is a diagram illustrating a power transmission device for a vehicle according to an embodiment. 2 is an example of a performance curve of a torque converter in a forward rotation direction when a lock-up clutch is in a released state.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that in the following examples, the figures are simplified or modified as appropriate, and the dimensional ratios, shapes, etc. of each part are not necessarily drawn accurately.

FIG. 1 is a diagram illustrating a power transmission device 50 of a vehicle 10 according to an embodiment.

Vehicle 10 is a hybrid vehicle that includes an engine 12, a first electric motor MG1, and a second electric motor MG2, which function as a power source. In the vehicle 10, an engine connection shaft 20, a power splitting mechanism 14, and a drive output shaft 26 are connected in order from the engine 12 side in a power transmission path PT between the engine 12 and drive wheels (not shown). Further, the second electric motor MG2 is connected to a drive output shaft 26 via a TC input shaft 22, a torque converter 16, a TC output shaft 24, and a reduction gear device 18.

Engine 12 is a well-known internal combustion engine. The first electric motor MG1 and the second electric motor MG2 are, for example, rotating electric machines having a motor function and a generator function, and are so-called motor generators. Note that the first electric motor MG1 and the second electric motor MG2 may be rotary electric machines without a generator function as long as they have a motor function.

The power split mechanism 14 includes, for example, a single pinion type planetary gear device. Sun gear S0 of the planetary gear system is connected to first electric motor MG1, carrier CA0 is connected to engine 12 via engine connection shaft 20, and ring gear R0 is connected to drive output shaft 26. On the inner circumferential side of the first electric motor MG1, the MG1 rotor shaft 40, which is the rotor shaft of the first electric motor MG1, is a cylindrical shaft, and the hollow part on the inner circumferential side of the MG1 rotor shaft 40 has an engine connection shaft 20. is inserted. Bearings B1 and B2 are disposed between the MG1 rotor shaft 40 and the engine connection shaft 20. The MG1 rotor shaft 40 and the engine connection shaft 20 are each rotatable about the axis CL, and are rotatable relative to each other. In the direction of the axis CL, the first electric motor MG1 is arranged between the engine 12 and the power split mechanism 14. The power splitting mechanism 14 is a well-known power splitting mechanism that mechanically splits the power output from the engine 12 to the first electric motor MG1 and the drive output shaft 26. The second electric motor MG2 is connected to the TC input shaft 22 so as to be capable of transmitting power. In this embodiment, a part of the TC input shaft 22 serves as the MG2 rotor shaft 42, which is the rotor shaft of the second electric motor MG2.

The torque converter 16 is a fluid transmission device that transmits power using fluid. The torque converter 16 transmits the power transmitted from the TC input shaft 22 to the TC output shaft 24 via oil OIL, which is a fluid. The power transmission device 50 is also a device that transmits power between the TC input shaft 22 and the TC output shaft 24. Note that oil OIL corresponds to "fluid" in the present invention.

The torque converter 16 includes a case 16c made up of, for example, a front cover and a rear cover that are welded together. The case 16c has a donut shape, and the inside thereof is filled with oil. The torque converter 16 includes, in the case 16c, a pump impeller 16p connected to a front cover, a turbine impeller 16t disposed opposite to the pump impeller 16p in the axis CL direction, and a pump impeller 16p and a turbine. and a stator impeller 16s disposed between the impeller 16t and the impeller 16t. The torque converter 16 transmits power via oil OIL between a pump impeller 16p and a turbine impeller 16t provided in a case 16c.

The output torque of the second electric motor MG2 is input to the pump impeller 16p via the front cover and the TC input shaft 22. The output torque of the torque converter 16 is output to the TC output shaft 24 via a turbine wheel 16t. The stator impeller 16s is an impeller that controls the flow of oil OIL to amplify torque. The one-way clutch OWC is provided between the stator wheel 16s and a fixed shaft 44 connected to the housing 30, which is a non-rotating member, and prevents the stator wheel 16s from rotating in the forward rotation direction. Allows rotation in the opposite direction. The forward rotation direction is, for example, the rotation direction of the torque converter 16 when the vehicle 10 is traveling forward.

The speed reduction device 18 is composed of, for example, a single pinion type planetary gear device, and a sun gear S1, a carrier CA1, and a ring gear R1 in the planetary gear device are connected to a TC output shaft 24, a drive output shaft 26, and a housing 30, respectively. There is.

The TC input shaft 22, the TC output shaft 24, and the drive output shaft 26 may each be composed of a plurality of members connected non-rotatably by spline fitting, for example.

The lock-up clutch LU is an engagement device that directly connects the pump wheel 16p and the turbine wheel 16t. The lock-up clutch LU is provided outside the case 16c, and is, for example, a dry engagement device. The lock-up clutch LU is a normally closed type engagement device. The normally closed type refers to a mechanism that can bring the lock-up clutch LU into an engaged state (=connected state) in a normal state where no control signal is applied, that is, in normal times. The normally open type refers to a mechanism in which the lock-up clutch LU is in a released state (=disconnected state) in a normal state where no control signal is applied, that is, in normal times.

The lock-up clutch LU is, for example, a dry friction engagement device or a dog clutch (=dog clutch). For example, when the lock-up clutch LU is a friction engagement device, it has a configuration similar to that of a mechanical clutch that transmits power by pressing the clutch disk with a spring against the flywheel of the engine in a vehicle equipped with a manual transmission. be. In the case of such a configuration, the engagement state is normally set by a spring, and the release fork is set to a released state by moving the release fork using, for example, a cable or a link mechanism. For example, when the lock-up clutch LU is a dog clutch, the lock-up clutch LU is a well-known dog clutch that includes a sleeve that is biased to be in an engaged state by a spring or the like, and a dog tooth that can be connected to the sleeve in a non-rotatable manner. It has the same structure as a dog clutch. In the case of such a configuration, normally the sleeve is connected to the meshing teeth by a spring or the like to be in the engaged state, and the connection between the sleeve and the meshing teeth is released by, for example, a shift fork mechanism to be in the released state. . Since the lock-up clutch LU is of a normally closed type, it is possible to suppress energy consumption, such as continuing to supply hydraulic pressure to an actuator, in order to maintain the engaged state of the lock-up clutch LU. In the case of this embodiment, energy consumption for maintaining the engaged state of the lock-up clutch LU is suppressed.

On the inner peripheral side of the torque converter 16, the fixed shaft 44, the TC output shaft 24, and the drive output shaft 26 are each cylindrical shafts. The TC output shaft 24 is inserted into the hollow part on the inner peripheral side of the fixed shaft 44, and the drive output shaft 26 is inserted into the hollow part on the inner peripheral side of the TC output shaft 24. Bearings B7 and B8 are disposed between the fixed shaft 44 and the TC output shaft 24. Bearings B9, B10, and B11 are disposed between the TC output shaft 24 and the drive output shaft 26. The fixed shaft 44, the TC output shaft 24, and the drive output shaft 26 are each arranged around the axis CL, and are rotatable relative to each other. The TC output shaft 24 and the drive output shaft 26 are each rotatable about the axis CL.

On the inner peripheral side of the second electric motor MG2, the MG2 rotor shaft 42, the TC output shaft 24, and the drive output shaft 26 are each cylindrical shafts. The TC output shaft 24 is inserted into the hollow part on the inner peripheral side of the MG2 rotor shaft 42, and the drive output shaft 26 is inserted into the hollow part on the inner peripheral side of the TC output shaft 24. Bearings B3 and B4 are disposed between the MG2 rotor shaft 42 and the TC output shaft 24. Bearings B5 and B6 are disposed between the TC output shaft 24 and the drive output shaft 26. The MG2 rotor shaft 42, the TC output shaft 24, and the drive output shaft 26 are each rotatable around the axis CL, and are rotatable relative to each other. In the direction of the axis CL, the second electric motor MG2 is arranged between the lockup clutch LU and the torque converter 16. That is, in the direction of the axis CL, the lock-up clutch LU is located on the opposite side of the torque converter 16 when viewed from the second electric motor MG2.

For example, an O-ring (not shown) is provided in the gap between the inner circumference of the MG2 rotor shaft 42 and the outer circumference of the TC output shaft 24 or the gap between the inner circumference of the TC output shaft 24 and the outer circumference of the drive output shaft 26. It is arranged. The hollow opening of the drive output shaft 26 is covered with a lid (not shown). Due to these, the torque converter 16 is made oil-tight.

FIG. 2 is an example of a performance curve of the torque converter 16 in the forward rotation direction when the lock-up clutch LU is in the released state.

The ratio of the TC input shaft rotation speed Nin [rpm], which is the rotation speed of the TC input shaft 22, to the TC output shaft rotation speed Nout [rpm], which is the rotation speed of the TC output shaft 24, is expressed as the rotation speed ratio α (=Nout/Nin ). The rotational speed ratio α is also the ratio of the turbine rotational speed Nt [rpm], which is the rotational speed of the turbine impeller 16t, to the pump rotational speed Np [rpm], which is the rotational speed of the pump impeller 16p (=Nt/Np). The ratio of the torque of the TC output shaft 24 to the torque of the TC input shaft 22 is referred to as a torque ratio β (=torque of the TC output shaft 24/torque of the TC input shaft 22). The torque ratio β represents the torque amplification function of the torque converter 16.

As shown in FIG. 2, the torque ratio β is highest when the rotation speed ratio α is near zero value (when the TC input shaft 22 starts rotating), and as the turbine rotation speed Nt increases, the pump rotation speed Np increases. The closer it gets, the lower the torque ratio β becomes. Generally, when the rotational speed ratio α becomes 0.8 to 0.9 or more and the pump rotational speed Np and the turbine rotational speed Nt become equal, the stator impeller 16s, which is in a rotation-blocking state, will instead turn the oil OIL. It starts to obstruct the flow. However, when the pump rotational speed Np and the turbine rotational speed Nt become equal, the stator impeller 16s, which had been in a rotation-blocked state, also starts to idle, and the torque ratio β becomes approximately "1". After this point, the torque is not amplified. The range of the rotational speed ratio α in which this torque is not amplified is the coupling range. On the other hand, the range of rotational speed ratio α in which the torque is amplified is the converter range.

When running in the converter range (especially when starting forward running), a high torque ratio β is required. On the other hand, during normal driving in the coupling range, a high torque ratio β is not required. When the vehicle is running in the converter range, it is mainly in the running state at the start of running, and when it is running normally in the coupling range, it is in other running states. Therefore, in general, the frequency and duration of the driving state are longer during normal driving in the coupling range than when driving in the converter range.

By idling the stator wheel 16s in the coupling range, a decrease in the transmission efficiency ρ of the torque converter 16 during normal running in the coupling range is suppressed, but this does not mean that 100% of the torque is transmitted. isn't it. When the lock-up clutch LU is engaged, the TC input shaft 22 and the TC output shaft 24 are directly connected, and the rotation of the TC input shaft 22 is directly transmitted to the TC output shaft 24.

According to the power transmission device 50 of this embodiment, the lock-up clutch LU that directly connects the pump impeller 16p and the turbine impeller 16t is provided outside the case 16c and is of a normally closed type. By providing the lockup clutch LU outside the case 16c of the torque converter 16, the lockup clutch LU can have a simple configuration. Furthermore, since the lock-up clutch LU is of the normally closed type, the engaged state of the lock-up clutch LU is maintained even without applying a control signal during normal driving in the coupling range of the torque converter 16. Thereby, it is possible to suppress energy consumption such as continuing to supply hydraulic pressure to the actuator in order to maintain the engaged state of the lock-up clutch LU.

According to the power transmission device 50 of the present embodiment, (a) an electric motor (specifically, the second electric motor MG2) functioning as a power source is disposed between the lock-up clutch LU and the torque converter 16; b) The lock-up clutch LU is a dry engagement device. If it is outside the case 16c of the torque converter 16, the lock-up clutch LU can easily be a dry normally closed type. Furthermore, since the dry lock-up clutch LU is located on the opposite side of the torque converter 16 when viewed from the second electric motor MG2, the lock-up clutch LU is prevented from being covered with the oil OIL that operates the torque converter 16. Thereby, the performance of the lock-up clutch LU is easily maintained.

The above-mentioned embodiments are examples of the present invention, and the present invention can be implemented with various modifications and improvements based on the knowledge of those skilled in the art without departing from the spirit thereof.

In the above-described embodiment, the lock-up clutch LU is a dry type engagement device, but the present invention is not limited thereto, and may be a wet type engagement device. By providing the lock-up clutch LU outside the case 16c, the degree of freedom in design is improved compared to when the lock-up clutch LU is provided inside the case 16c, so that the lock-up clutch LU has a simple configuration even if it is a wet type. is possible.

In the above embodiment, the vehicle 10 is configured such that the power transmission path PT is provided with the power splitting mechanism 14 and the drive output shaft 26, and the second electric motor MG2 is connected to the drive output shaft 26 via the torque converter 16. However, the present invention is not limited to this. For example, a vehicle to which the present invention is applied has an engine and one electric motor as a power source, and is equipped with an engagement device that connects and disconnects power transmission between the engine and the electric motor, and has an engagement device that connects and disconnects power transmission between the engine and the electric motor. A torque converter may be provided in the power transmission path, or an electric vehicle may have only an electric motor without an engine as a power source.

10: Vehicle, 16: Torque converter, 16c: Case, 16p: Pump wheel, 16t: Turbine wheel, LU: Lock-up clutch, OIL: Oil (fluid)

Claims (1)

A power transmission device for a vehicle equipped with a torque converter that transmits power via fluid between a pump impeller and a turbine impeller provided in a case,
A power transmission device for a vehicle, wherein a lock-up clutch that directly connects the pump wheel and the turbine wheel is provided outside the case and is of a normally closed type.

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