Selectable torque path torque converter architecture

Abstract

To provided an architecture for coupling the output of a prime mover to a rotationally-driven device, the architecture being switchable between two different torque paths.SOLUTION: The architecture includes: a selectable switching device; a terminal output member; and a torque transfer device having an intermediate output member. The selectable switching device is coupled to the output of the prime mover and is selectively and alternately coupled between first and second states. In the first state, the switching device is connected to the torque transfer device, so that the torque transfer device is rotationally driven by the prime mover and the terminal output member is rotationally driven by the intermediate output member of the torque transfer device. In the second state, the switching device is connected to the terminal output member, so that the terminal output member is rotationally driven by the prime mover and the torque transfer device is disconnected from the rotation of the prime mover and is not rotationally driven.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] Cross - reference to related applications This application is a non - provisional application and claims the benefit of priority of U.S. Provisional Patent Application No. 63 / 240,545, filed on September 9, 2021, and U.S. Provisional Patent Application No. 63 / 315,884, filed on March 2, 2022, and incorporates the entire contents of these applications herein by reference.

[0002] Broadly speaking, the present invention relates to a powertrain incorporating a torque converter, and more particularly to a novel architecture for a torque converter that can be used in a motor vehicle powertrain or other devices driven thereby.

Background Art

[0003] Today, the automotive industry is gradually shifting from vehicles using internal combustion engines (ICEs) to electric vehicles. Although the technology is improving, one of the drawbacks of fully electric vehicles (EVs) is that, at present, due to limitations in battery technology, the driving range of such vehicles may be restricted. For a driver who only needs to move within a narrow range, this may not be considered inconvenient. However, for a driver who needs to travel a distance that exceeds the driving range of a typical fully electric vehicle, at least sometimes, usually, they have to choose either to stop for a long time to recharge the battery or to own a second vehicle with a long driving range.

[0004] Even in ICE vehicles, by improving the efficiency of the powertrain, the driving range limitation can be alleviated. One of the currently adopted methods is to stop the ICE for at least a certain period of time when the vehicle is not moving, and restart the ICE promptly when the intention to move is detected, such as when the driver's foot leaves the vehicle's brake pedal.

[0005] There are also vehicles that fall between the two options above: hybrid vehicles (HV) and plug-in hybrid vehicles (PHEV). In hybrid vehicles, a combustion engine and an electric motor are used alternately as the vehicle's power source. Overall, hybrid vehicles are more fuel-efficient than combustion engine vehicles, but are less fuel-efficient than electric vehicles. On the other hand, plug-in hybrid vehicles run primarily on electricity, but use a combustion engine as a backup power source to extend the vehicle's range.

[0006] While the above describes vehicles and powertrains, powertrains can also be used in other applications where a rotational input is required for a device. Such applications include, but are not limited to, driving gear reduction units that can connect their output to other devices requiring a rotational input.

[0007] One component of such a powertrain is a torque converter. A torque converter is connected between the powertrain's prime mover (ICE, electric motor (EM), or ICE / EM combination) and the output used to rotationally drive the inputs of devices such as the transmission and gear reduction mechanism.

[0008] Simply put, a torque converter can be described as a hydrodynamic circuit configured to increase input torque and transmit the increased torque as output torque to the input of a device such as a transmission or gear reduction mechanism. The torque converter has a front cover and a rear cover, which work together to define a shell. Furthermore, this shell defines an internal chamber where the hydrodynamic circuit is located. Typically, the output of the prime mover rotates the shell, which in turn rotates the impeller inside the shell. The impeller directs the hydrodynamic fluid radially outward and then axially forward toward the turbine. The force transmitted to the turbine by this fluid is used to drive the turbine to rotate. The fluid that leaves the turbine flows radially inward and then axially back toward the impeller. A stator is located between the turbine and the impeller. The stator increases the transmitted torque by redirecting the fluid so that it is efficiently transmitted to the impeller. Because this is a fluid dynamics circuit, a torque converter can increase torque by generating a speed difference (slip) between the input side (impeller) and the output side (turbine).

[0009] The purpose and function of a torque converter is to have both the ability to increase torque and to create a speed difference. Increasing torque is effective when starting a vehicle from a complete stop or when towing. However, there are also situations where the torque converter's lock-up function, which locks the front cover (the input to the torque converter) with the output of the torque converter, is useful. One such situation is when driving on a road in a steady state. This lock-up state is achieved by including a lock-up clutch in the torque converter. [Overview of the project] [Problems that the invention aims to solve]

[0010] In the lock-up state, all components of the torque converter continue to rotate, and torque is transmitted through the torque converter via the shell / front cover, internal lock-up clutch, output hub, and output shaft, but without the involvement of the hydraulic connections to the impeller, turbine, and stator. This allows for greater efficiency than the speed difference allowed by the torque converter's hydrodynamic circuitry, but the inertia required to rotate the components still results in inertial inefficiencies in the drivetrain. These losses occur in powertrains incorporating either an ICE, EM, or ICE / EM as the prime mover. Furthermore, the torque converter's maximum rotational speed becomes a limiting factor when operating the driveline at higher rotational speeds. [Means for solving the problem]

[0011] In addressing the shortcomings and other limitations of the prior art described above, in one embodiment, the present invention provides an architecture for connecting the output of a prime mover to a prime mover-driven device, which is switchable between two different torque paths.

[0012] In another embodiment, the present invention provides an architecture comprising a selectable switch, a torque transmission device, and an end output member. The selectable switch is configured to be connected to the output of a prime mover. The selectable switch is also configured to be connected selectively and alternately to one of a first state and a second state. The torque transmission device includes an input and an intermediate output member, the intermediate output member being connected to the end output member. In the first state, the selectable switch connects the output of the prime mover to the torque transmission device, thereby the torque transmission device is rotationally driven by the prime mover, and the end output member is rotationally driven by the torque transmission device. In the second state, the selectable switch connects the output of the prime mover to the end output member, thereby the end output member is rotationally driven by the prime mover, and the torque transmission device is disconnected from the rotation of the prime mover and is not rotationally driven.

[0013] In another embodiment, in the second state, the terminal output member is directly driven by the prime mover.

[0014] In a further embodiment, the system further includes a second torque transmission device connected between the prime mover and the terminal output member, wherein in the second state, a selectable switching device connects the output of the prime mover to the terminal output member via the second torque transmission device.

[0015] In an additional embodiment, the system further includes a synchronous device connected between the torque transmission device and the output of the prime mover.

[0016] In yet another embodiment, the synchronous device is selectively connected to a torque transmission device, causing the torque transmission device to rotate at a speed within a predetermined speed difference range between it and either the prime mover or the terminal output member, and allowing the outputs of the torque transmission device and the prime mover to be reconnected via a selectable switching device.

[0017] In yet another embodiment, the synchronous device allows the torque transmission and the prime mover output to be reconnected via a selectable switch over the entire operating range during the desired operating conditions of torque increase or converter slip.

[0018] In an additional embodiment, the synchronization device and the selectable switching device are incorporated into a common device.

[0019] In yet another embodiment, the device further includes a synchronization device connected between the torque transmission device and the terminal output member.

[0020] In a further embodiment, the device being driven is the vehicle's transmission.

[0021] In another embodiment, the present invention relates to an architecture for connecting an output member of a prime mover to a device driven by the prime mover, comprising: an input member configured to be connected to the output member of the prime mover; a torque transmission device; an end output member configured to be connected to the device to be driven; and a selectable switch connected between the input member, the torque transmission device, and the end output member, wherein the selectable switch is connectable in a first state in which the input member is rotatably connected to the torque transmission device and the torque transmission device rotationally drives the output member; and the selectable switch is connectable in a second state in which the input member is rotatably connected to the end output member and the input member rotationally drives the end output member, wherein in the second state the input member is disconnected from the rotation of the torque transmission device, thereby the torque transmission device is not rotationally driven by the input member.

[0022] In yet another embodiment, in the second state, the terminal output member is directly driven by a prime mover.

[0023] In a further embodiment, the system further includes a second torque transmission device connected between the prime mover and the terminal output member, wherein in the second state, a selectable switching device connects the output of the prime mover to the terminal output member via the second torque transmission device.

[0024] In an additional embodiment, the system further includes a torque transmission device and a synchronous device connected between the output of the prime mover and one of the end output members.

[0025] In yet another embodiment, the synchronous device is selectively connected to a torque transmission device, causing the torque transmission device to rotate at a speed within a predetermined speed difference range between the prime mover and one of the end output members, and allowing the outputs of the torque transmission device and the prime mover to be reconnected via a selectable switch over the entire operating range during operating conditions in which torque increase or converter slip is desired.

[0026] In yet another embodiment, the device being driven is the vehicle's transmission.

[0027] Further objects, features, and advantages of the present invention will become readily apparent to those skilled in the art upon consideration of the following description, which includes the claims, and reference to the drawings attached hereto and forming a part hereof.

Brief Description of the Drawings

[0028] [Figure 1] FIG. 1 is a schematic diagram of a torque converter architecture incorporating the principles of the present invention. [Figure 2] FIG. 2 is a schematic cross-sectional view of an embodiment of the torque converter architecture shown in FIG. 1.

Mode for Carrying Out the Invention

[0029] When used in the following description, terms indicating directions such as “upward” and “downward” are used based on the orientation of the elements shown in the figures. For this reason, “upward” refers to the direction toward the top of the figure, and “downward” refers to the direction toward the bottom of the figure. “Left” and “right” are interpreted in the same way. The terms “inward direction” or “inside,” “outward direction” or “outside” indicate, regardless of whether the central axis is shown in the figure, generally the direction toward the central axis of the component being referred to or the direction away from the central axis. Thus, a surface facing in the axial direction is an axial surface. That is, the axial surface faces in the direction along the central axis. Thus, a radial surface faces in the radial direction, that is, generally in the direction away from the central axis or toward the central axis. However, it will be understood that in actual practice, the reference directions used in this specification may not necessarily coincide with the way and direction of installation of the corresponding components or devices.

[0030] Referring here to the drawings, a torque converter architecture incorporating the principle of the present invention is schematically shown in Figure 1 and indicated by 10. The torque converter architecture 10 is located between the prime mover 12 and the inputs of downstream drivetrain elements, gear reduction mechanisms, or other devices 14, one example of which is shown in Figure 2. The prime mover 12 may be an internal combustion engine (ICE), an electric motor (EM), or a combination thereof (ICE / EM).

[0031] The torque converter architecture 10 includes, as its broad components, a selectable switch 16, a torque converter 18, and an output 20 such as an output shaft. During operation, torque from the prime mover 12 is transmitted to the selectable switch 16. Depending on the state of the selectable switch 16, the torque from the prime mover 12 may be directed to the torque converter 18 and then to the output 20 (first operating state), or it may be directed directly to the output 20 (second operating state). If a direct drive state between the output of the prime mover 12 and the input of the downstream device 14 is desired, the selectable switch 16 transmits the torque directly to the output 20. In this second operating state, the torque converter 18 is not passed through at all, and no rotational input is supplied to the torque converter 18.

[0032] The torque converter 18 provides a hydrodynamic circuit configured to increase the input torque and transmit the increased torque as output torque to the downstream driven device 14. The torque converter 18 includes a front cover 22 and a rear cover 24, which cooperate to define a shell 26. Furthermore, the shell 26 defines an internal chamber 28, in which the hydrodynamic circuit is housed.

[0033] The input shaft 29 transmits torque to the torque converter 18. This torque is generally received by the shell 26 at the front cover 22 and transmitted to the impeller 30, which is usually mounted internally to the rear cover 24. The impeller 30 directs the hydrodynamic fluid radially outward and then axially forward toward the turbine 32. The force transmitted to the turbine 32 by this fluid drives the turbine 32 to rotate. The fluid leaving the turbine 32 flows radially inward and then axially back toward the impeller 30. The stator 34 is located between the turbine 32 and the impeller 30 and is supported by a one-way clutch 35. The stator 34 increases the transmitted torque by redirecting the fluid so that it is efficiently transferred toward the impeller 30.

[0034] The turbine 32 is connected to the turbine output hub 36. The turbine output hub 36 transmits output torque to the output member 20 via an intermediate output member 37 and a one-way clutch 38. This output member 20 transmits torque to the downstream device 14. A clutch / selectable device may be used instead of the one-way clutch 38. In addition, a damper assembly (not shown) may be provided on the torque converter 18 for noise, vibration, and harshness (NVH) countermeasures before transmitting the output torque to the output member 20.

[0035] As described above, a lock-up clutch assembly, typically consisting of a piston / clutch assembly, is provided within the torque converter so that the input from the front cover can be locked at the turbine output hub. When locked up in this way, the torque transmitted to the downstream equipment does not pass through the hydrodynamic circuit of the impeller and turbine. However, the front and rear covers, impeller, turbine, stator, damper, and other components of the torque converter still continue to rotate, along with associated losses of inertia and efficiency.

[0036] In the torque converter architecture 10 of the present invention, the lock-up clutch is omitted from the torque converter 18, and instead an upstream selectable switching device 16 is employed. As a result, not only are losses caused by the rotation of the torque converter when it is locked up avoided, but the overall size of the torque converter is reduced, and the high-pressure hydraulic circuit required to operate the lock-up clutch is also eliminated.

[0037] Architecture 10, which employs the principles of the present invention, can be implemented in configurations other than torque converters that utilize torque transmission devices. For example, instead of the torque converter 18, other devices such as fluid couplings, hydrostatic couplings, or other devices that apply torque can be used.

[0038] It will be understood that the selectable switching device 16 may employ various types of selectable clutches / devices. Examples of such devices include, but are not limited to, hydraulic clutches, synchronizers, and selectable electric clutches. As mentioned above, when implemented, such a device must be of a type that can alternately direct the torque transmitted from the selectable switching device 16 to the input shaft 29 of the torque converter 18 or directly to the output member 20.

[0039] A schematic is shown in Figure 1, but a modified physical implementation of the torque converter architecture 10 is shown in Figure 2. In the figure, the prime mover 12 is represented by a torque generator, i.e., an electric motor (EM) 40 having a fixed stator 41 and a rotatable rotor 42. (Although shown here as an EM, the prime mover 12 could also be shown as an internal combustion engine (ICE) or a combination of both.) When torque is applied to the rotor 42 of the EM 40, this torque is transmitted to a selectable switch 16. Depending on the state of the selectable switch 16, the torque is transmitted to one of two output drive members 44, 46, which are transmitted to either the input shaft 29 or the output member 20 of the torque converter 18, respectively, but not to both simultaneously. As shown in Figure 2, the output member 20 is provided as an output shaft and is positioned concentrically with the input shaft 29. The output member 20 and the input shaft 29 are supported by bearings or other means to rotate independently of each other.

[0040] When torque is directed to the torque converter 18, the torque is transmitted from the selectable switch 16 to the input shaft 29. The input shaft 29 is fixedly connected to the front cover 22 of the torque converter shell 26 and rotates the rear cover 24. As described above, the turbine 32 is driven by a fluid connection between the impeller 30 (held by the rear cover 24) and the turbine 32, and the torque is increased and transmitted to the turbine 32 as the stator 34 efficiently returns the hydraulic fluid to the impeller. Here again, the turbine 32 includes a turbine output hub 36. In the first state of the selectable switch 16, the turbine output hub 36 is connected to the output member 20 via a one-way clutch 38 and drives the output shaft 20.

[0041] As shown in Figure 2, the output member 20 is also the input shaft 46 to the downstream device 14, which is shown as the gearbox, i.e., the transmission 48. The gearbox 48 includes a shift fork 50 that rides axially on a shift rail 52. The shift fork 50 provides both forward and reverse operation of the gearbox 48 by connecting the input shaft 48 to either the forward drive gear set 54 or the reverse drive gear set 56 via a synchronizer 58. It will be understood that, in this way, the increase in torque during both forward and reverse operation can be utilized and output to further driven devices or components (not shown) via the output shaft 60, when the torque is directed through the torque converter 18. It will also be understood that various types of connection / forward / reverse switching mechanisms may be employed instead of those described above.

[0042] By determining the direction of the torque and bypassing the torque converter 18, the torque is transmitted directly from the selectable switching device 16 to the output member 20 via the output drive 46. Subsequently, as described above, the output member 20 acts directly as the input shaft 48 of the downstream device 14 / gearbox 48 without any increase in torque.

[0043] In an alternative configuration of this architecture, a second torque transmission device 64 may be implemented between the selectable switch 16 and the output member 20 when the selectable switch 16 is in a second state. The second torque transmission device 64 is preferably a different type of torque transmission device from the torque converter 18, and may be, for example, a slip clutch or a peak torque limiter.

[0044] When the output member 20 is directly driven by the prime mover 12 (shown as EM40 in Figure 2), the torque converter 18 is not driven, maximizing efficiency, and in some cases, the rotation may actually stop. To enable the undriven torque converter 18 to be reconnected to the prime mover 12 over the operating speed range of the system, a synchronous device 62 may be optionally employed. A schematic diagram of the synchronous device 62 is shown in Figure 1.

[0045] The synchronous device 62 brings the input shaft 29, the shell 26, and the impeller 30 of the torque converter 18 to a speed within a specific speed difference range relative to the rotation of the output member of the prime mover 12, thereby allowing for easy reconnection of the selectable switching device 16 for transmitting torque via the torque converter 18. Alternatively, the synchronous device 62 may bring the input shaft 29 to a speed within a specific speed difference range relative to the rotation of the output member 20.

[0046] The synchronous device 62 may be in the form of a hydraulic clutch, an electric clutch, an electric motor, or other device (manual or automatic). A clutch device is schematically shown as the synchronous device 62 in Figure 1, but is not limited thereto. In another configuration, the synchronous device 62 may be combined with a standalone device 16' having a selectable changeover device 16 and / or the synchronous device 62 may be incorporated into such a standalone device 16'.

[0047] The above description is intended to illustrate at least one preferred embodiment incorporating the principles of the present invention. Those skilled in the art will truly understand that modifications, alterations, and changes can be made to the invention without departing from the true intent and fair scope of the invention as defined in the appended claims. Accordingly, the terms used herein are intended to be understood as descriptive rather than restrictive.

Claims

1. 1. An architecture for connecting an output of a prime mover to a device driven by said prime mover, comprising: a selectable switching device configured to be connected to the output of the prime mover and selectively and alternately connected in one of a first state and a second state; a torque transmitting device having an input and an intermediate output member and disposed downstream of the selectable switching device; a distal output member; the intermediate output member is connected to the distal output member; in the first state, the selectable switching device connects the output of the prime mover to the torque transfer device, whereby the torque transfer device is rotationally driven by the prime mover and the distal output member is rotationally driven by the torque transfer device; In the second state, the selectable switching device connects the output of the prime mover to the distal output member, whereby the distal output member is rotationally driven by the prime mover and the torque transfer device is decoupled from the rotation of the prime mover and is not rotationally driven.

2. The architecture of claim 1 , wherein in said second state, said distal output member is directly driven by said prime mover.

3. 2. The architecture of claim 1, further comprising a second torque transfer device connected between the prime mover and the distal output member, wherein in the second state, the selectable switching device connects the output of the prime mover to the distal output member via the second torque transfer device.

4. The architecture of claim 1 , further comprising a synchronizer connected between the torque transfer device and the output of the prime mover.

5. 5. The architecture of claim 4, wherein the synchronizer is selectively connected to the torque transfer device to rotate the torque transfer device at a speed within a predetermined speed differential between the prime mover and one of the distal output members, and to enable reconnection of the torque transfer device and the output of the prime mover via the selectable switching device.

6. 5. The architecture of claim 4, wherein the synchronizer enables the torque transfer device and the output of the prime mover to be reconnected via the selectable switching device throughout an operating range during operating conditions where increased torque or converter slip is desired.

7. The architecture of claim 4 , wherein the synchronizer and the selectable switching device are incorporated into a common device.

8. The architecture of claim 1 , further comprising a synchronizer connected between the torque transfer device and the distal output member.

9. The architecture of claim 8 , wherein the driven device is a vehicle transmission.

10. 1. An architecture for connecting an output member of a prime mover to a device driven by said prime mover, comprising: an input member configured to be connected to the output member of the prime mover; a torque transmission device; a terminal output member configured to be connected to the driven device; a selectable switching device connected between the input member and the torque transmitting device, and between the input member and the distal output member; the selectable switching device is connectable in a first state in which the input member is rotatably connected to the torque transmitting device and the torque transmitting device rotationally drives the output member; the selectable switching device is connectable in a second state in which the input member is rotatably connected to the distal output member and the input member rotationally drives the distal output member; In the second state, the input member is rotationally decoupled from the torque transmitting device, such that the torque transmitting device is not rotationally driven by the input member.

11. The architecture of claim 10 , wherein in the second state, the distal output member is directly driven by the prime mover.

12. 11. The architecture of claim 10, further comprising a second torque transfer device connected between the prime mover and the distal output member, wherein in the second state, the selectable switching device connects the output of the prime mover to the distal output member via the second torque transfer device.

13. The architecture of claim 10 , further comprising a synchronizer connected between the torque transfer device and one of the output of the prime mover and the distal output member.

14. 14. The architecture of claim 13, wherein the synchronizer is selectively connected to the torque transfer device to rotate the torque transfer device at a speed within a predetermined speed differential range with the prime mover and one of the distal output members, such that the torque transfer device and the output of the prime mover can be reconnected via the selectable switching device throughout an operating range during operating conditions where increased torque or converter slip is desired.

15. The architecture of claim 14 , wherein the synchronizer and the selectable switching device are incorporated into a common device.

16. The architecture of claim 10 , wherein the driven device is a vehicle transmission.

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