LAUNCH TORUS TORQUE CONVERTER

Abstract

A torque converter having an impeller, a turbine, and a stator disposed between the impeller and the turbine is provided. The torque converter has an axially thin design, with a torus width to torque converter diameter ratio of about 0.15 to 0.17, by way of example. In some variations, the stator has twisted blades that have lower shell blade angles than core blade angles with respect to the center line of torque converter flow, at both the inlet and outlet.

Description

TECHNICAL FIELD

The present disclosure relates to hydrodynamic drive mechanisms, and more particularly, to torque converter assemblies including an impeller, a turbine, and a stator.

BACKGROUND

The statements in this section merely provide background information related to the present disclosure and may or may not constitute prior art.

Current automatic power transmissions generally include a hydrodynamic input device such as a torque converter or fluid coupler. The torque converter automatically disengages the rotating engine output shaft from the transmission input shaft during vehicle idle conditions to enable the vehicle to stop without stalling the engine. The torque converter also functions as a torque multiplier which increases engine torque delivered to the transmission in the lower speed range until torque converter output speed approximately matches the input (engine) speed.

The torque converter includes three bladed, fan-like wheels: an engine-driven impeller, a fluid turbine, and a fluid stator. The impeller driven by the engine accelerates fluid for passage to the turbine. The turbine converts the fluid energy coming from the impeller into mechanical energy, which is transmitted to the input shaft of a transmission. The stator mechanism disposed between the fluid inlet of the impeller and the fluid outlet of the turbine redirects the fluid from the turbine to the impeller thereby improving the flow efficiency and increasing the torque multiplication of the hydrodynamic torque converter. The fluid passes from the inner torus section of the impeller substantially radially outward in a toric path and then through the path in the turbine in a substantially toric path back to the stator.

A stator is made up of a plurality of stator blades, which are connected at one end to a relatively small ring, the inner part of the shell, and at the other end to a larger ring, the core. Fluid flowing through the stator passes along the stator blades. These blades force the fluid to change direction so fluid exiting the stator enters the pump flowing in the same direction as the pump is rotating, thereby conserving power.

One of the measures of torque converter performance is the “K-factor.” The K-factor is the ratio of the input speed of the torque converter to the square root of the torque output of the engine, as measured at any torque converter operating point. In turn, the “operating point” of a torque converter is typically defined by the ratio of the output speed to the input speed which is also known as the speed ratio.

Torque converters occupy space in a powertrain assembly, while space is at a premium. Transmissions with high gear content leave less axial space for the torque converter. However, torque converters having axially compact tori typically have been known to carry an increased risk of cavitation, which increases the K-factor and could present undesirable noise. All things being equal, it is desirable to achieve a low K-factor across the entire speed ratio range. Increased efficiency of energy transfer through a torque converter is also a highly desirable goal. Accordingly, there is a need for a torque converter that can fit into a small axial space, but that can still meet the desired design goals for the K-Factor and overall performance of the torque converter.

SUMMARY

The present disclosure provides a torque converter having an axially compact torus and blades that provide an unexpectedly good hydrodynamic performance, given the axial size of the torus. In some embodiments, the torque converter has high K-factor extension and coupling capacity to enable tight electronically controlled capacity clutch (ECCC) slip speed control.

In one variation, a torque converter is provided that includes an annular housing, a pump member, a turbine member, and a stator member. The turbine member opposes the pump member. In one variation, the torque converter has a torus width to torque converter diameter ratio of about 0.15 to 0.17.

In some embodiments, the torque converter disclosed herein has one or more of the following characteristics: an aspect ratio (torus width divided by torus height) of about 0.73 to 0.78; a passage height to torque converter diameter ratio of about 0.053 to 0.057; a torus position (2 times the stator shell radius divided by the torque converter diameter) of about 0.55 to about 0.61; a torus area ratio distribution of about 75% to 90% at partial length fraction; a coupling speed ratio of about 0.89 to 0.90; a retention (K_cp/K_s) of about 1.01 to 1.10; a stator torus having a longer length at the shell than at the core; a ratio of the torus length at the shell to the torus length at the core of about 1.2 to 1.9; twisted stator blades with lower blade angles at the shell than at the core; stator blades having an inlet core angle minus inlet shell angle of about 12 to 17 degrees; and stator blades having an outlet core angle minus outlet shell angle of about 9 to 22 degrees.

In one variation, which may be combined with or separate from the other variations described herein, a torque converter for a motor vehicle is provided. The torque converter includes an impeller member configured to be driven hydraulically by a prime mover of the motor vehicle and a turbine member configured to receive fluid energy from the impeller member and convert the fluid energy to mechanical energy. The turbine member is disposed opposite the impeller member. The impeller member and the turbine member cooperate to define a torus width L_t and a torque converter diameter D. A stator member is disposed between the impeller member and the turbine member. The stator member is configured to increase torque multiplication of the torque converter. The torque converter has a torus width L_t to torque converter diameter D ratio (L_t/D) in the range of about 0.15 to about 0.17.

In another variation, which may be combined with or separate from the other variations described herein, a torque converter for a motor vehicle is provided. The torque converter includes an impeller member configured to be driven hydraulically by a prime mover of the motor vehicle and a turbine member configured to receive fluid energy from the impeller member and convert the fluid energy to mechanical energy. The turbine member is disposed opposite the impeller member. A stator member is disposed between the impeller member and the turbine member. The stator member is configured to increase torque multiplication of the torque converter. The stator member has a plurality of stator blades. Each stator blade of the plurality of stator blades extends at an inlet core stator blade angle θ from a center line C of torque converter flow at a core side of the stator member and at an inlet side of the stator member. Each stator blade extends at an outlet core stator blade angle γ from a center line C of torque converter flow at the core side of the stator member and at an outlet side of the stator member. Further, each stator blade extends at an inlet shell stator blade angle α from a center line C of torque converter flow at a shell side of the stator member and at an inlet side of the stator member, and each stator blade extends at an outlet shell stator blade angle β from a center line C of torque converter flow at the shell side of the stator member and at the outlet side of the stator member. The inlet shell stator blade angle α is less than the inlet core stator blade angle θ, and the outlet shell stator blade angle β is less than the outlet core stator blade angle γ.

Further features and aspects of the present invention will become apparent by reference to the following description and appended drawings wherein like reference numbers refer to the same component, element or feature.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way.

FIG. 1 is a schematic diagram of a torque converter according to the principles of the present disclosure;

FIG. 2A is a graph of torus area ratio as a function of torus length fraction of the torque converter of FIG. 1, in accordance with the principles of the present disclosure;

FIG. 2B is a schematic cross-sectional view of a flow path through the controlled area torus portion of the torque converter of FIG. 1, according to the principles of the present disclosure;

FIG. 3A is a plan view of a portion of a stator for use with the torque converter of FIG. 1, in accordance with the principles of the present disclosure;

FIG. 3B is a side view of the stator of FIG. 3A, according to the principles of the present disclosure;

FIG. 3C is a schematic cross-sectional view of a blade of the stator of FIGS. 3A-3B, taken along the line 3C-3C of FIG. 3A at the core of the stator, in accordance with the principles of the present disclosure;

FIG. 3D is a schematic cross-sectional view of a blade of the stator of FIGS. 3A-3B, taken along the line 3D-3D of FIG. 3A at the shell of the stator, according to the principles of the present disclosure; and

FIG. 4 is a graph of torque ratio, K-factor, and efficiency as a function of speed ratio of four variations of the torque converter of FIG. 1, in accordance with the principles of the present invention.

DESCRIPTION

Referring to the drawings, wherein like reference numbers refer to like components, in FIG. 1 a schematic diagram view of a torque converter 10 illustrated in accordance with an embodiment of the present invention. The torque converter 10 is disposed in a vehicle between a power source or prime mover 12 and a transmission 14. The prime mover 12 is, for example, an engine or motor and is operable to provide torque to a rotatable engine output shaft 16. It should be appreciated that other types of prime movers may be used without departing from the scope of the present invention.

The transmission 14 generally includes at least one rotatable transmission input shaft 18 that transfers torque to a plurality of gear sets, a plurality of shafts, and a plurality of torque transmitting mechanisms (not shown) to provide a plurality of speed or gear ratios. It should be appreciated that the input shaft 18 as illustrated may alternatively be considered an output shaft of the torque converter 10 and may be a separate shaft rotatably coupled to the transmission input shaft. The plurality of shafts may include layshafts or countershafts, sleeve and center shafts, reverse or idle shafts, or combinations thereof. It should be appreciated that the specific arrangement and number of the gear sets and the specific arrangement and number of the shafts within the transmission 14 may vary without departing from the scope of the present disclosure.

The torque converter 10 includes a pump or impeller 20 and a turbine 22 disposed opposite the impeller 20. A stator 24 is disposed between inner portions of the turbine 22 and impeller 20, as schematically illustrated in FIG. 1. The impeller 20 is generally annular in shape and includes a plurality of fins or blades (not shown) oriented to transfer rotational energy from the impeller 20 to a hydraulic fluid (not shown) disposed within an annular housing (not shown) that surrounds that impeller 20, turbine 22, and stator 24. The turbine 22 is generally annular in shape and includes a plurality of fins or blades (not shown) that oppose the impeller 20 and are oriented to transfer rotational energy from the hydraulic fluid (not shown) to the turbine 22.

The stator 24 may be rotatably coupled through a one-way clutch 26 to a stationary shaft 28. The stator 24 includes a plurality of angled fins or blades (not shown in FIG. 1, see FIGS. 3A-3B) extending radially and circumferentially from a center of the stator 24 to redirect hydraulic fluid that exits the turbine 22. The one-way clutch 26 allows rotation of the stator 24 in the rotational direction of the impeller 20 and resists or prevents rotation of the stator 24 in the rotational direction opposite the rotational direction of the impeller 20. In the example provided, the stationary shaft 28 is coupled to a stationary component in the transmission.

The torque converter 10 has an axially compact torus design, such that the ratio (L_t/D) of torus width (L_t) to torque converter diameter D is about 0.15 to 0.17, and in some variations, about 0.16 or 0.163. The following Table 1 provides additional parameters that define an embodiment of the torque converter 10. The variables used are graphically illustrated in FIG. 1. For example, FIG. 1 schematically illustrates the torque converter diameter D, the torus width L_t, the passage height h, the stator shell radius R_s, the torus height d, the two-dimensional length of the stator blade at the core Ls_c (described in further detail below) and the two-dimensional length of the stator blade at the shell Ls_s (described in further detail below).

TABLE 1
Torque Converter 10 Design Ratios.
Torus Design Ratios
	Aspect		Torus position	Torus Area
Lt/D	Ratio, Lt/d	h/D	2 * Rs/D	Ratio Distribution
0.15 to	0.73 to	0.053 to	0.55 to 0.61	75% to 90% at partial
0.17	0.78	0.057		length fraction

The values in Table 1 may be considered to be exact, in some embodiments, or approximate, in other embodiments. Thus, the torque converter 10 includes a torus width L_t to torque converter diameter D ration (L_t/D) of about 0.15 to 0.17, an aspect ratio (L_t/d) of about 0.73 to 0.78, a passage height h to torque converter diameter D ratio (h/D) of about 0.053 to 0.057, a torus position (2*R_s/D) of about 0.55 to 0.61, and a torus area ratio distribution of about 75% to 90%.

In other variations, the shape and dimensions of the torque converter 10, including the impeller 20, the turbine 22, and the stator 24, may vary in length, width, and other dimensions based on design considerations. For example, the torque converter 10 could have a larger torque converter diameter D, while keeping the same L_t/D ratio of about 0.15 to 0.17, or at about 0.16 or 0.163.

The torque converter 10 may have a controlled torus flow area ratio, as disclosed in U.S. Pat. No. 7,082,755, commonly assigned to GM Global Technology Operations, Inc., and herein incorporated by reference in its entirety. For example, referring to FIGS. 2A-2B, the controlled torus area ratio is illustrated graphically and schematically. One half of the torus 30 of the torque converter 10 is illustrated. The inlet is indicated at reference number 34 for the impeller 20 and 32 for the turbine 22. As shown graphically in FIG. 2A, the gross torus flow area ratio decreases from the turbine inlet 32 to a minimum point M between about 0.6 and 0.8 torus length fraction, which is the distance along the torus length TL. From the minimum point M, the gross torus flow area ratio increases to the outlet 34 of the turbine 22. Thus, the torus area ratio distribution decreases along the torus length TL by an amount in the range of 75% to 90%, by way of example, as indicated in Table 1. This change in gross flow area ratio reduces or eliminates the energy losses which otherwise might occur within the flow path. In this embodiment, both the turbine 22 and the impeller 20 have a torus structure wherein the inlet (which is 32 for the turbine 22 and 34 for the impeller 20) of the passage 36 are larger in annular area than the middle annular area, particular at the minimum point M.

Referring now to FIGS. 1, 3A-3D and Table 2, details of one variation of the stator 24 are described. The stator 24 has a shell 38, a core 40, and a plurality of stator blades 42. The torque converter 10 may have a higher number of blades than traditional designs. For example, the impeller 20 may have 37 pump blades (not illustrated), and the turbine 22 may have 35 turbine blades (not illustrated). The stator 24 may have 20-42 stator blades 42, depending on the desired K-factor. Each stator blade 42 has a first end 44 affixed to the stator shell 38 and a second end 46 affixed to the stator core 40.

Referring to FIG. 3C, a cross-sectional view of a stator blade 42 taken along the line 3C-3C in FIG. 3A at the core 40 is illustrated. The stator blade 42 extends at an angle θ from the center line C of torque convertor flow at the core 40 at the inlet side 48 of the stator 24. The stator blade 42 extends at an angle γ from the center line C of torque converter flow at the core 40 at the outlet side 50 of the stator 24. Referring to FIG. 3D, a cross-sectional view of one of the stator blades 42 of FIG. 3C is taken along the line 3D-3D in FIG. 3A at the shell 38 of the stator 24. The stator blade 42 extends at an angle α from the center line C of torque converter flow at the shell 38 at the inlet side 48 of the stator 24. The stator blade 42 extends at an angle β from the center line C of torque converter flow at the shell 38 at the outlet side 50 of the stator 24. The blades 42 are twisted such that they have lower shell blade angles α, β at the shell 38 than the core blade angles θ, γ at the core 40, at both the inlet and outlet sides 48, 50 of the stator 24. For example, the inlet core angle θ minus the inlet shell angle α may be about 12-17 degrees; and for example, the outlet core angle γ minus the outlet shell angle β may be about 9-22 degrees.

The stator blades 42 may also have a longer two-dimensional length at the shell than at the core. For example, the stator blade length at the shell Ls_s is greater than the stator blade length at the core Ls_c (see FIG. 1 for graphical representation though because of the schematic nature of the stator 24 in FIG. 1, Ls_s does not appear larger than Ls_c). The ratio of stator blade length at the shell Ls_c to stator blade length at the core Ls_c may be about 1.2 to 1.9, by way of example. The blade angle and stator length at the shell and core parameters are also shown in Table 2.

TABLE 2
Launch Torus Torque Converter Stator Design parameters.
Description	Parameter	Range
Longer two-dimensional	Lss/Lsc	1.2 to 1.9
stator blade length at
shell Lss than core Lsc
Twisted blades 42 with	Inlet core blade angle θ	12 to 17 degrees
lower shell blade angles	minus inlet shell blade
α than core blade angles	angle α
θ at inlet 48
Twisted blades 42 with	Outlet core blade angle γ	9 to 22 degrees
lower shell blade angles	minus outlet shell blade
β than core blade angles	angle β
γ at outlet 50

Referring now to FIG. 4 and Table 3, the torque converter performance is illustrated with four different K-factor designs of the torque converter 10A, 10B, 10C, 10D. The torque ratio as a function of speed ratio is illustrated at set 52 of the torque converter data 10A, 10B, 10C, 10D. The K-factor as a function of speed ratio is illustrated at set 54 of the torque converter data 10A, 10B, 10C, 10D. The efficiency as a function of speed ratio is illustrated at set 56 of the torque converter data 10A, 10B, 100, 10D. For torque converters 10A-10D, the torque converters 10A-10D had a coupling speed ratio of about 0.89 to 0.90 and a retention (K_cp/K_s) of about 1.01 to 1.10, where K_cp is the K-factor at the coupling speed ratio and K_s is the K-factor at the stall speed ratio. Table 3 also shows these parameters.

TABLE 3
Coupling Speed Ratio Capacity.
Coupling Speed Ratio Retention (Kcp/Ks)
0.89 to 0.90         1.01 to 1.10

The description of the invention is merely exemplary in nature and variations that do not depart from the general essence of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.

Claims

1. A torque converter for a motor vehicle, the torque converter comprising: an impeller member configured to be driven hydraulically by a prime mover of the motor vehicle;a turbine member configured to receive fluid energy from the impeller member and convert the fluid energy to mechanical energy, the turbine member being disposed opposite the impeller member, the impeller member and the turbine member cooperating to define a torus width Lt and a torque converter diameter D; anda stator member disposed between the impeller member and the turbine member, the stator member being configured to increase torque multiplication of the torque converter, whereinthe torque converter has a torus width Lt to torque converter diameter D ratio (Lt/D) in the range of about 0.15 to about 0.17.

2. The torque converter of claim 1, wherein the stator member has a plurality of stator blades, the plurality of stator blades comprising about 20 to about 42 stator blades.

3. The torque converter of claim 2, wherein the impeller member and the turbine member cooperate to define a torus height d, the torque converter having an aspect ratio (torus width Lt divided by torus height d, Lt/d) in the range of about 0.73 to about 0.78.

4. The torque converter of claim 3, wherein the torque converter has a torus passage height h to torque converter diameter D ratio (h/D) of about 0.053 to about 0.057.

5. The torque converter of claim 4, wherein the stator member defines a stator shell radius Rs, the torque converter having a torus position (2 times the stator shell radius Rs divided by the torque converter diameter D, 2*Rs/D) in the range of about 0.55 to about 0.61.

6. The torque converter of claim 5, wherein at least one of the impeller member and the turbine member defines a torus area ratio distribution that decreases along a torus length TL of one of the impeller member and the turbine member by an amount in the range about 75% to 90%.

7. The torque converter of claim 6, wherein each stator blade extends at an inlet core stator blade angle θ from a center line C of torque converter flow at a core side of the stator member and at an inlet side of the stator member; wherein each stator blade extends at an outlet core stator blade angle γ from a center line C of torque converter flow at the core side of the stator member and at an outlet side of the stator member; wherein each stator blade extends at an inlet shell stator blade angle α from a center line C of torque converter flow at a shell side of the stator member and at the inlet side of the stator member; wherein each stator blade extends at an outlet shell stator blade angle β from a center line C of torque converter flow at the shell side of the stator member and at the outlet side of the stator member; wherein the inlet shell stator blade angle α is less than the inlet core stator blade angle θ; and wherein the outlet shell stator blade angle β is less than the outlet core stator blade angle γ.

8. The torque converter of claim 7, wherein the inlet core stator blade angle θ minus the inlet shell stator blade angle α is in the range of about 12° to about 17°; and wherein the outlet core stator blade angle γ minus the outlet shell stator blade angle β is in the range of about 9° to about 22°.

9. The torque converter of claim 8, wherein each stator blade is twisted and has a greater two-dimensional length at the shell side of the stator member than at the core side of the stator member.

10. The torque converter of claim 9, wherein each stator blade has a shell length Lss at the shell side of the stator member and each stator blade has a core length Lsc at the core side of the stator member, the ratio of the shell length Lss to the core length Lsc being in the range of about 1.2 to about 1.9.

11. The torque converter of claim 10, wherein the impeller member has 37 pump blades.

12. The torque converter of claim 11, wherein the turbine member has 35 turbine blades.

13. The torque converter of claim 1, wherein the torque converter has a coupling speed ratio in the range of about 0.89 to about 0.90.

14. The torque converter of claim 13, wherein the torque converter has a retention (K-factor at the coupling speed ratio divided by K-factor at a stall speed ratio, Kcp/Ks) in the range of about 1.01 to about 1.10.

15. The torque converter of claim 14, wherein the torus width Lt to torque converter diameter D ratio (Lt/D) is about 0.16.

16. A torque converter for a motor vehicle, the torque converter comprising: an impeller member configured to be driven hydraulically by a prime mover of the motor vehicle;a turbine member configured to receive fluid energy from the impeller member and convert the fluid energy to mechanical energy, the turbine member being disposed opposite the impeller member; anda stator member disposed between the impeller member and the turbine member, the stator member being configured to increase torque multiplication of the torque converter, the stator member having a plurality of stator blades, wherein each stator blade of the plurality of stator blades extends at an inlet core stator blade angle θ from a center line C of torque converter flow at a core side of the stator member and at an inlet side of the stator member; wherein each stator blade extends at an outlet core stator blade angle γ from a center line C of torque converter flow at the core side of the stator member and at an outlet side of the stator member; wherein each stator blade extends at an inlet shell stator blade angle α from a center line C of torque converter flow at a shell side of the stator member and at an inlet side of the stator member; wherein each stator blade extends at an outlet shell stator blade angle β from a center line C of torque converter flow at the shell side of the stator member and at the outlet side of the stator member; wherein the inlet shell stator blade angle α is less than the inlet core stator blade angle θ; and wherein the outlet shell stator blade angle β is less than the outlet core stator blade angle γ.

17. The torque converter of claim 16, wherein the inlet core stator blade angle θ minus the inlet shell stator blade angle α is in the range of about 12-17°; and wherein the outlet core stator blade angle γ minus the outlet shell stator blade angle β is in the range of about 9-22°.

18. The torque converter of claim 17, wherein each stator blade is twisted and has a greater two-dimensional length at the shell side of the stator member than at the core side of the stator.

19. The torque converter of claim 18, wherein each stator blade has a shell length Lss at the shell side of the stator member and each stator blade has a core length Lsc at the core side of the stator member, the ratio of the shell length Lss to the core length Lsc being in the range of about 1.2 to about 1.9.

20. The torque converter of claim 19, wherein the impeller member has 37 pump blades, wherein the turbine member has 35 turbine blades, and wherein the plurality of stator blades comprises about 20-42 stator blades.