JP4090788B2 - Torque converter - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a torque converter that transmits power through a fluid, and more particularly to a blade structure of a stator wheel.
[0002]
[Prior art]
As is well known, in a fluid torque converter, a stator wheel interposed in a torus formed by a pump impeller and a turbine runner is from a stalled state where the rotational speed difference between the pump impeller and the turbine runner is large to a predetermined rotational speed difference. It is provided for the purpose of torque amplification to improve the poor transmission efficiency due to the fluid transmission. Since the stator wheel has a large rotational speed difference between the pump impeller and the turbine runner, the fluid flowing back from the turbine runner back to the pump impeller in the converter area (low speed ratio area) where the fluid flow hits the blade surface (pressure side blade surface) side. It acts to deflect the flow on the blade surface side and guide it in a direction that does not impede the rotation of the pump impeller, and in the coupling region (high speed ratio region) where the difference in rotation is small, fluid flows on the back surface (suction side blade surface) side of the blade. When this flow comes into contact, it idles in the same direction as the rotation direction of the pump impeller and the turbine runner and acts to prevent this flow from being disturbed. In order to produce such an action, the stator wheel is generally connected to an appropriate fixing member via a one-way clutch that is free to rotate in the same direction with respect to the pump impeller and the turbine runner and locks the rotation in the reverse direction. .
[0003]
[Problems to be solved by the invention]
By the way, the stator wheel is located on the innermost peripheral side of the torus, and the diameter of the portion where the stator blade is located is the smallest diameter, so that a large number of stator wheels are arranged with a predetermined twist with respect to the axis on the circumference. The intervals between the stator blades are close. In addition, a predetermined gap must be provided between the tail portion and the head portion of each stator blade for die cutting during manufacture. For these reasons, the chord length of the stator blade is limited by the relationship between the number of blades disposed and the gap that must be provided between the blades. On the other hand, the cross-sectional shape of the stator blade is generally an airfoil streamline in order to reduce the occurrence of pressure loss. By adopting such a streamlined cross-sectional shape, the thickness of the blade cross-section is relative to the chord length. It must be thin.
[0004]
Due to the chord length restriction and the blade thickness restriction as described above, the stator blade cross-section is absolutely thin. Especially in the inner ring side portion of the blade, the arrangement pitch of each blade is arranged. Since the circumferential length of the portion is limited, the thickness is further reduced due to the restriction, which makes it difficult to ensure the strength of the stator blade.
[0005]
The present invention has been devised in view of such circumstances, and a main object thereof is to provide a structure for improving the strength of a stator blade in a torque converter. Moreover, this invention makes it the further objective to improve the intensity | strength of the type | mold used in order to manufacture a stator wheel.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a torque converter comprising a pump impeller, a turbine runner that forms a torus in cooperation with the pump impeller, and a stator wheel having a blade interposed in the torus. The tail portion of the blade of the stator wheel has a plane connecting the pressure side blade surface and the suction side blade surface at least on the inner ring side of the blade, and the plane and the suction side blade surface are connected by a convex curved surface. And In this case, it is effective that the plane of the tail portion of the blade has a corner portion between the blade and the pressure side blade surface.
[0007]
In the above configuration, it is effective that the plane of the tail portion of the blade is a plane substantially parallel to the axis of the stator wheel. In this case, it is effective that the entire tail portion of the blade on the outer ring side is a convex curved surface.
[0008]
Alternatively, in the configuration described above, the blade of the stator wheel has a flat surface in the entire tail portion of the blade from the inner ring side to the outer ring side, and the blade tail portion connected to the pressure side blade surface. It is also effective to make the connecting side a convex curved surface.
[0009]
[Action and effect of the invention]
In the configuration according to claim 1 of the present invention, the blade tail is thicker than the conventional structure in which the tail of the blade is a streamlined arcuate surface. The strength of the stator blade is improved by improving the strength on the blade inner ring side where it is difficult to increase the chord length. The side where the blade tail is connected to the suction side blade surface is a convex curved surface, and the fluid flow along the suction side blade surface in the coupling region where the stator wheel is pushed by the fluid flow and idles Therefore, the generation of resistance due to peeling is prevented, so that the transmission efficiency in the high speed ratio region of the torque converter can be maintained in the same manner as in the conventional structure in which the entire tail portion of the blade is an arcuate curved surface.
[0010]
Moreover, in the structure of Claim 2, since the cross-sectional area of the braid | blade can be enlarged by making the tail part of a braid | blade into a corner | angular part, the intensity | strength of a braid | blade can be improved.
[0011]
Next, in the configuration of the third aspect, when the stator wheel is manufactured by casting, the shape of the stator blade can be cut along the surface by matching the dividing surface of the die with the plane of the tail portion of the stator blade. Therefore, the thickness of the projection side of the mold required for mold division on the stator blade head side can be increased to a length equal to the gap, especially on the inner ring side where the gap between the blades is small. It is possible to improve the strength of the mold.
[0012]
Furthermore, when the structure according to claim 4 is adopted, the fluid flow along the pressure side blade surface in the converter region where the stator wheel is fixed to the fluid flow is separated at the tail of the blade on the outer ring side. Therefore, the transmission efficiency in the low speed ratio region of the torque converter can be maintained as in the conventional structure in which the entire tail portion of the blade is an arcuate curved surface. In addition, in this case, the stator wheel is manufactured, because the gap between the blades is larger on the outer ring side of the stator wheel than the inner ring side, so that the mold dividing surface is located at the center of the gap between the blades as in the conventional case. Even if they are positioned, the thickness of the protrusion side of the mold can be increased to some extent. Therefore, according to this configuration, it is possible to achieve both maintenance of transmission efficiency in the low speed ratio region of the torque converter and improvement of the strength of the mold for manufacturing the stator wheel.
[0013]
On the other hand, when the structure according to claim 5 is adopted, when the stator wheel is manufactured by casting, the dividing surface of the mold is matched with the plane of the stator blade tail so that the curvature is larger than the head of the blade. Thus, in the conventional parting structure, it becomes a stator blade shape that can be removed without the protrusions that cannot be avoided in the parting part of the tail part, and the strength of the mold for manufacturing the stator wheel can be further improved. .
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described from the overall configuration of a torque converter with reference to the drawings. First, FIG. 2 shows an axial cross section of a torque converter to which the present invention is applied. Since the torque converter includes the lockup clutch 4, the torque converter includes an outer shell structure in which the front cover 40 and the pump shell 10 are combined. A turbine runner which forms a torus in cooperation with the pump impeller 1 with respect to the pump impeller 1 configured by fixing a large number of pump blades 11 to the pump shell 10 by brazing or the like and attaching an inner shell 12. 2 is configured by attaching a large number of turbine blades 21 to a turbine shell 20 fixed to a turbine hub 23 together with a damper plate 41 of a lock-up clutch 4 by riveting or the like, and attaching an inner shell 22. The stator wheel 3 with 31 interposed is fixed to the one-way clutch 5 and is integrated into an inner ring 30 aligned with the pump shell 10 and the turbine shell 20 and an outer ring 32 aligned with the inner shells 12 and 22. The stator blade 31 is provided.
[0015]
FIG. 1 shows a cross-section of two of the stator blades 31 on the side of the inner ring 30 with the inner ring circumferential surface developed in a plane (hereinafter, the direction in which the developed surface extends is the X-axis direction, and the axial direction of the stator wheel is the Y-axis direction. In the same way, the inner ring side tail portion 31b of the blade 31 has a flat surface Ff on the side connected to the pressure side blade surface (upper left surface in the drawing) Fp. The side where Ff is connected to the suction side wing surface (the lower right surface in the drawing) Fs is defined as a convex curved surface Fc. Specifically, the stator blade surface has a convex surface with a large curvature at the blade head 31a, a pressure side blade surface Fp that is a concave curved surface with a small curvature connected to one side thereof, and a convex curved surface with a small curvature connected to the other side. A suction side blade surface Fs and a tail surface connected to both blade surfaces Fp and Fs on the opposite side. Since the side connected to the pressure side blade surface Fp of the blade tail portion 31b is the plane Ff as described above, a corner portion is formed between the pressure side blade surface Fp and the tail plane Ff.
[0016]
As described above, the tail portion 31b of the stator blade 31 has a shape that is obtained by cutting off a streamline tail portion that is elongated in accordance with the conventional shape, so that the blade cross section is thicker than the chord length. With such a shape, for example, when the distance in the X-axis direction between the head portion 31a and the tail portion 31b of the adjacent blade 31 is the same as the conventional one, the thickness of the blade 31 may be made thicker than the conventional one. Therefore, the strength of the stator blade 31 on the inner ring 30 side can be improved.
[0017]
According to the second feature of the present invention, the plane Ff of the blade tail portion 31b is a surface in the YZ axial direction substantially parallel to the axis of the stator wheel 3. This configuration is associated with stator wheel mold manufacturing. In the conventional general manufacturing method, the dividing surface of the die forming the blade portion of the stator wheel is the same as the dividing surface on the outer ring 32 side indicated by the broken line in FIG. The shape extends in the axial direction. That is, the mold division is a mold that forms a pressure side blade surface Fp from a portion P1 where each blade head 31a is in contact with the axial tangent to a portion P2 where the blade tail portion 31b is in contact with the axial tangent (hereinafter, in the illustrated position for convenience of explanation). And a mold that forms the suction side blade surface Fs from the same portion P1 to the portion P2 (also referred to as a lower die). These two molds are configured to be matched in the X-axis direction gap portion between the blades from the portion P1 of one blade head portion 31a to the portion P2 of the other blade tail portion 31b. Of course, these die-matching surfaces Dx and Dy are axially-aligned surfaces (in detail, this surface has a draft angle, and is therefore an inclined surface having a minute gradient with respect to the axis), that is, a YZ direction surface. Dy and the X-Z direction plane Dx orthogonal to the axial direction and passing through the parts P1 and P2 respectively, so that no projection with a narrow width that is not preferable for maintaining mold strength is generated in any mold. The axial alignment surface is positioned at the center of the gap in the X-axis direction. Such a parting structure is possible without generating a narrow protrusion on the outer ring side where the width of the gap in the X-axis direction is wide and the blade 31 has a large inclination with respect to the axial direction, that is, the Y-axis direction. On the inner ring side where the width of the blade 31 is extremely narrow and the inclination of the blade 31 with respect to the axial direction is small, a narrow protrusion is generated.
[0018]
Therefore, in the mold splitting configuration according to the present invention, as described above, the plane Ff of the blade tail portion 31b is substantially parallel to the axis of the stator wheel 3 (this surface is strictly a plane having a draft gradient). Therefore, the term “substantially parallel” as used in the present invention means including parallel to the draft plane.) Ff, and the axially divided plane Dy is made to coincide with this plane Ff as shown in FIG. Thus, a narrow protrusion is not formed at the tip of the upper mold. In this case, a protruding portion (a hatched portion in the drawing) is formed at the tip of the lower die as in the conventional case. The width of the protruding portion in the X-axis direction is the axial direction dividing surface Dy and the blade tail portion. Due to the configuration shifted to the 31b side, it becomes much wider than the conventional case where the dividing surface in the axial direction is arranged at the center of the gap.
[0019]
With such a configuration, when the stator wheel 3 is manufactured by casting, the stator blade shape can be removed by matching the mold dividing surface with the plane Ff of the stator blade tail portion 31b. Since the required thickness of the projection side of the mold can be increased to a length equal to the gap in the X-axis direction between the stator blades, the strength of the mold for manufacturing the stator wheel 3 can be improved.
[0020]
On the other hand, as shown in FIG. 3 in which the outer ring side cross section of two of the stator blades 31 is developed with the outer ring circumferential surface being flat, in this embodiment, the blade cross-sectional shape of the stator blade 31 on the outer ring side is Like the conventional one, the entire blade tail 31b is a convex curved surface. Therefore, the parting structure on the outer side of the stator blade is the same as the conventional one for the reason mentioned above. Thus, the configuration that follows the conventional structure of the outer ring side portion of the stator blade 31 is useful for improving the transmission efficiency in the low speed ratio region.
[0021]
In the stator blade structure having such a configuration, in the low speed ratio region from the stall region to the converter region where the rotation of the turbine runner 2 is zero or low with respect to the rotation of the pump impeller 1 shown in FIG. The flow of the discharged fluid is substantially in the Y-axis direction as indicated by the white arrow Sp in FIG. 1, so that the fluid hits the pressure side blade surface Fp of each blade 31 of the stator wheel whose rotation is restricted, Since it flows along the blade surface Fp and flows away from the blade surface Fp at the blade tail portion 31b toward the inlet side of the pump impeller 1, on the inner ring side shown in FIG. 1, when leaving the corner portion at the blade tail portion 31b, Although loss due to turbulence occurs, the flow on the outer ring side shown in FIG. 3 is less lossy, and the increase in pressure loss can be suppressed overall.
[0022]
On the other hand, in the high speed ratio coupling region where the rotations of the pump impeller 1 and the turbine runner 2 are substantially equal, the flow of the fluid discharged from the turbine runner 2 is indicated by the white arrow Ss in the figure. The fluid generally comes into contact with the suction side blade surface Fs of each blade 31 of the stator wheel by being in the X-axis direction, flows along the suction side blade surface Fs while pushing away the blade 31, and the blade surface Fs at the blade tail portion 31b. 1, the flow is directed toward the inlet side of the pump impeller 1, so that the blade tail 31 b flows away from the blade 31 without any disturbance on the inner ring side shown in FIG. 1 or the outer ring side shown in FIG. 3. Thus, according to the present embodiment, an increase in pressure loss can be suppressed comprehensively from the stall region to the coupling region.
[0023]
FIG. 4 shows the characteristics of the transmission efficiency realized by this embodiment compared with the conventional one. The solid line in the figure shows the relationship between the speed ratio and the transmission efficiency of the torque converter according to the embodiment of the present invention, and the transmission efficiency is improved on the high speed ratio side as compared with the conventional one shown by the broken line in the figure.
[0024]
FIG. 5 shows a cross-sectional shape on the blade outer ring side in the second embodiment in which the blade cross-sectional shape on the inner ring side of the stator blade in the first embodiment is directly extended to the outer ring side in the same manner as FIG. FIG. That is, in this embodiment, the blade 31 of the stator wheel has a flat surface Ff on the side where the blade tail portion 31b is connected to the pressure side blade surface Fp in the entire blade tail portion 31b from the inner ring side to the outer ring side. The side connected to the side wing surface Fs is a convex curved surface Fc. In this embodiment, the parting surface Dy is provided at the center of the gap in the X-axis direction between the adjacent blades 31 as in the first embodiment, but the blade tail 31b. The mold matching surface Dx on the side is different from the mold matching surface on the outer ring side in the first embodiment, and is matched with the corner portion P2 of the blade 31.
[0025]
In the case of this second embodiment, for the same reason as described in the mold splitting structure on the blade inner ring side in the previous embodiment, the strength is increased on the outer ring side of the blade 31 by increasing the thickness of the tail portion 31b and further adjacent to each other. The gap in the X-axis direction between the blades 31 can be widened by the amount of cutting of the blade tail 31b, and the mating surface Dx on the blade tail 3b side having a large curvature can be matched with the corner portion P2 of the blade. It is more advantageous than the first embodiment in securing the strength.
[0026]
The present invention has been described in detail based on the two embodiments. However, the present invention is not limited only to the disclosed contents of these embodiments, and various specific details can be made within the scope of the matters described in the claims. Needless to say, the configuration can be changed.
[Brief description of the drawings]
FIG. 1 is a circumferentially developed partial cross-sectional view showing a split structure between an inner ring side portion of a stator blade of a torque converter according to a first embodiment of the present invention and that portion of a production mold;
FIG. 2 is an axial sectional view showing an overall configuration of the torque converter.
FIG. 3 is a circumferentially developed partial cross-sectional view showing a split structure between an outer ring side portion of the stator blade and that portion of a production die.
FIG. 4 is a graph showing characteristics of the torque converter.
FIG. 5 is a circumferentially developed partial cross-sectional view showing a split structure of an outer ring side portion of a stator blade of a torque converter according to a second embodiment and that portion of a production die.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Pump impeller 2 Turbine runner 3 Stator wheel 31 Stator blade 31b Blade tail part 30 Inner ring 32 Outer ring Fp Pressure side blade surface Fs Suction side blade surface Ff Plane Fc Convex curve surface

Claims (5)

In a torque converter comprising a pump impeller, a turbine runner that forms a torus in cooperation with the pump impeller, and a stator wheel having a blade interposed in the torus,
The tail portion of the blade of the stator wheel has a plane connecting the pressure side blade surface and the suction side blade surface at least on the inner ring side of the blade, and the plane and the suction side blade surface are connected by a convex curved surface. Torque converter. The torque converter according to claim 1, wherein a flat surface of the tail portion of the blade has a corner portion with the pressure side blade surface. The torque converter according to claim 1, wherein a plane of the tail portion of the blade is a plane substantially parallel to an axis of the stator wheel. 4. The torque converter according to claim 1, wherein the tail portion on the outer ring side of the blade has a convex curved surface throughout. The blade of the stator wheel has a flat surface in the entire tail portion of the blade from the inner ring side to the outer ring side. The torque converter according to claim 1, 2, or 3.

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