JPH0783310A - Coreless torque converter - Google Patents

Abstract

PURPOSE:To reduce the capacity of torque at a low speed ratio region and improve the capacity of torque at a high speed ratio sphere by making the blade shape of an impeller blade the one that makes a flow passage sectional area reduced gradually toward an outlet side, in the case of a coreless torque converter which does not possess a core at a portion where respective blades are gathered. CONSTITUTION:A coreless torque converter is equipped with a pump impeller 2 to be coupled to a converter cover 1 into which motive power is inputted from an engine; a turbine runner 4 to which a transmission input shaft is connected; and a stator 6 which is to be provided at a case through a one-way clutch 5, at an inner diameter portion interposed between the pump impeller 2 and the turbine runner 4. The pump impeller 2 is made up by having an impeller shell 2a and an impeller blade 2b, and in this instance, the blade inner end curve shape of the impeller blade 2b is set so that it may become a blade shape by which a flow passage sectional area is reduced gradually toward an outlet from at inlet. As a result, the reduction of the capacity of torque at a low speed ratio region is made possible.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coreless torque converter which is applied to an automatic transmission for a vehicle or the like and has no core at a portion where blades of a pump impeller, a turbine runner and a stator are gathered.

[0002]

2. Description of the Related Art Conventionally, as a coreless torque converter, for example, one disclosed in Japanese Patent Laid-Open No. 5-79545 is known.

According to the above-mentioned conventional source, the impeller blades of the pump impeller have the same flow passage cross-sectional area as the stator.
Disclosed is a blade shape having a cut portion obtained by cutting a portion connecting a straight line or a curved line between an impeller exit intersection point of a virtual core line defined on an impeller and an impeller angle point corresponding to a corner portion of the stator on the impeller side. Has been done.

[0004]

However, in the above-mentioned conventional coreless torque converter, since the flow passage cross-sectional area of the pump impeller is set to be constant from the inlet to the outlet, it functions as a fluid coupling. Since the part to be used becomes a constant volume, performance tuning according to the speed ratio cannot be performed as described below, and sufficient performance cannot be obtained in developing a torque converter that supports recent improvements in fuel consumption. .

For example, in order to improve the idle fuel consumption in the low speed ratio range, it is considered that the loss is positively generated to reduce the torque capacity. Therefore, as shown in the dotted line in FIG. 6, the blade shape of the pump impeller is cut off so that only the outer peripheral portion is cut off so that the flow passage cross-sectional area of the pump impeller is kept constant from the inlet to the outlet. Loss occurs, the torque capacity can be reduced in the low speed ratio range, and the fuel consumption at the time of idling can be improved. However, in the case of this shape, the torque capacity becomes insufficient in the high speed ratio region where the circulation flow rate is small.

Therefore, it is necessary to make the inlet area of the impeller substantially the same as that of the stator. In this case, as shown by the solid line in FIG. 6, the flow passage cross-sectional area of the pump impeller is kept constant from the inlet to the outlet. The reduction in torque capacity in the low speed ratio range is not achieved, and the fuel efficiency during idling is reduced.

That is, the conventional structure cannot meet the contradictory characteristic requirements of the torque capacity reduction in the low speed ratio range and the torque capacity improvement in the high speed ratio range.

The present invention has been made by paying attention to the above problems, and an object of the present invention is to provide a coreless structure having no core at the portion where the blades of the pump impeller, the turbine runner and the stator are gathered. In a torque converter, it is possible to achieve both a reduction in torque capacity in a low speed ratio range and an improvement in torque capacity in a high speed ratio range, and to make it possible to tune the effect margin according to the vehicle type in which it is installed.

[0009]

In order to achieve the above object, a coreless torque converter of the present invention has a pump impeller, a turbine runner, and a stator, and has no core at a portion where these blades are gathered. In the torque converter, the impeller blades of the pump impeller have a blade shape that gradually reduces the flow passage cross-sectional area from the inlet to the outlet.

[0010]

First, the circulation flow in the low velocity ratio region flows over the entire surface of the blade from the impeller blade inlet to the blade outlet.

In this flow, a part of the flow that flows from the stator to the pump impeller and acts as a torque converter is curvilinearly cut so as to have a blade shape that gradually reduces the flow passage cross-sectional area from the inlet to the outlet. It flows into the inner edge of the wing.

The region from the inner end of the blade to the inlet of the turbine runner is a region that acts as a fluid coupling in which the torque increasing function is hardly exhibited, and the flow rate and flow velocity in the fluid coupling action region due to the inflow to this region. Increase, loss increases, and torque capacity decreases.

Further, the flow of the circulating flow in the high speed ratio region is a flow that is closer to the impeller shell side from the impeller blade inlet to the blade outlet. Further, the approaching direction gradually becomes stronger as the speed ratio becomes higher.

Due to this flow, even if a part of the impeller blade is cut off in a curved manner by the inner end of the blade, most of the flow flowing from the stator to the pump impeller passes through the impeller blade and the fluid cup There is less inflow into the area that acts as a ring.

Therefore, the circulation flow rate acting as the torque converter is increased, the flow rate and the flow velocity in the fluid coupling working region are reduced, the loss is reduced, and the torque capacity is increased.

Further, the impeller blades of the pump impeller are
Due to the blade shape that gradually reduces the flow passage cross-sectional area from the inlet to the outlet, the torque in the low speed ratio range is set by setting the impeller blade inlet cross-sectional area of the pump impeller, the impeller blade outlet cross-sectional area, and the cross-sectional area change rate. It is possible to optimally tune according to the required performance of the vehicle type or the like to which the capacity reduction allowance and the torque capacity increase allowance in the high speed ratio range are applied, for example, the starting performance and the fuel consumption.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on the embodiments shown in the drawings.

First, the structure will be described.

FIG. 1 is a sectional view showing a coreless torque converter according to an embodiment of the present invention, and FIG. 2 is an end view of an impeller blade taken along the line EF of FIG.

As shown in FIG. 1, the coreless torque converter of the embodiment includes a pump impeller 2 connected to a converter cover 1 to which a rotational driving force is input from an engine,
A turbine runner 4 is arranged at a position opposite to the pump impeller 2 and a transmission input shaft (not shown) is connected via a turbine hub 3, and an inner diameter portion sandwiched between the pump impeller 2 and the turbine runner 4. , A case (not shown) has three elements such as a stator 6 provided via a one-way clutch 5, and the portions where these blades 2, 4, 6 are gathered together are cores whose blade tips are close to each other. Do not have.

The pump impeller 2 comprises an impeller shell 2a and an impeller blade 2b.
In b, the curved shape of the blade inner end 2c is set so that the flow passage cross-sectional area gradually decreases from the inlet to the outlet.

That is, the impeller blade inlet cross-sectional area of the pump impeller 2 is determined by an arbitrary point B on the impeller blade inlet surface including the point A, where the impeller angle point A corresponds to the corner portion of the stator 6 on the impeller side. . Further, the impeller blade outlet cross-sectional area of the pump impeller 2 is determined by an arbitrary point C on the impeller blade outlet surface. Then, the point of the blade inner end is set so that the cross-section change from the determined impeller blade inlet cross-sectional area to the impeller blade outlet cross-sectional area is gradually performed, and the blade inner end 2c is connected by connecting a plurality of set inner end points. The curved shape of is set.

Impeller blade 2b set in this way
In view of the cross section E-F on the streamline that actually flows, the outlet angle α ′ (<α) is smaller than the conventional outlet angle α by setting the blade inner end 2c.

Next, the operation will be described.

[Operation in Low Velocity Ratio Region] FIG. 3 is a diagram showing a flow pattern in the low velocity ratio region. In the low velocity ratio region, the flow flows over the entire blade surface from the impeller blade inlet to the blade outlet.

In this flow, a part of the flow that flows from the stator 6 to the pump impeller 2 and acts as a torque converter flows into the blade inner end 2c that is cut off in a curved manner.

The region from the blade inner end 2c to the inlet of the turbine runner 4 is a region that acts as a fluid coupling in which the torque increasing function is hardly exhibited, and the flow rate in the fluid coupling action region due to the inflow into this region. Also, the flow velocity increases, the loss increases, and the torque capacity decreases.

[Operation in High Speed Ratio Range] FIG. 4 is a diagram showing a flow pattern in the high speed ratio range. In the high speed ratio range, the flow is close to the impeller shell 2a side from the impeller blade inlet to the blade outlet. It becomes a flow. Further, the approaching direction gradually becomes stronger as the speed ratio becomes higher.

Due to this flow direction, most of the flow flowing from the stator 6 to the pump impeller 2 passes through the impeller blade 2b even if a part of the impeller blade 2b is cut off by the inner blade edge 2c. Over time, the amount of flow into the region acting as the fluid coupling decreases. Therefore, the circulation flow rate acting as the torque converter is increased, the flow rate and the flow velocity in the fluid coupling action region are decreased, the loss is reduced, and the torque capacity is increased.

[Setting of Impeller Blade] The characteristic that the circulating flow is closer to the impeller shell 2a side as the speed ratio becomes higher, and gradually approaches from the impeller blade inlet to the blade outlet. Show. That is, as the velocity ratio increases, the flow passage cross-sectional area gradually changes due to the relationship that the outlet-side flow passage cross-sectional area becomes narrower than the inlet-side flow passage cross-sectional area.

On the other hand, as in the conventional case, even if the impeller blade inlet to the blade outlet have the same sectional area as the flow passage sectional area of the stator, the capacity increase in the high speed ratio region cannot be expected.

However, when the impeller blades 2b of the pump impeller 2 have a blade shape that gradually reduces the flow passage cross-sectional area from the inlet to the outlet, as in the embodiment, the low speed ratio side is curvedly cut off. In addition, the blade inner end 2c increases the loss, and the torque capacity can be reduced. On the high speed ratio side, the circulation flow rate acting as a torque converter is increased due to the blade shape along the flow pattern, so that the high speed ratio region It is possible to achieve an increase in torque capacity. Although the torque ratio and efficiency are improved by reducing the loss, the dependency of this loss on the torque capacity is low.

Moreover, the impeller blade inlet cross-sectional area of the pump impeller 2 is determined by an arbitrary point B on the impeller blade inlet surface, and the impeller blade outlet cross-sectional area of the pump impeller 2 is an arbitrary point C on the impeller blade outlet surface. Since the impeller blade shape is set so that the cross-section change from the impeller blade inlet cross-sectional area to the impeller blade outlet cross-sectional area that is determined by the above is gradually performed, these points B, C and the cross-sectional area change rate are set. By setting, it is possible to tune optimally according to the required performance of the vehicle type that applies the torque capacity reduction allowance in the low speed ratio range and the torque capacity increase allowance in the high speed ratio range, for example, starting performance and fuel efficiency. it can.

[Comparison of Torque Converter Characteristics] FIG. 5 shows a characteristic comparison chart of the torque capacity coefficient, torque ratio, and efficiency of the coreless torque converter of the embodiment and the conventional coreless torque converter having the basic structure.

As is clear from this characteristic, the torque capacity coefficient τ significantly decreases in the low speed ratio region where the speed ratio is about 0.5 or less, and improves in the high speed ratio region where the speed ratio exceeds about 0.5.

Further, the efficiency η and the torque ratio t are ensured to have a predetermined improvement margin. Particularly, the efficiency η is greatly improved in the region where the speed ratio is around 0.5, and the torque ratio t is greatly improved in the stall torque ratio when the speed ratio is 0.

From the above comparison, it is confirmed that the above-described action is achieved when the impeller blades 2b of the pump impeller 2 have a blade shape that gradually reduces the flow passage cross-sectional area from the inlet to the outlet.

Next, the effect will be described.

(1) In a coreless torque converter that does not have a core at the portion where the blades of the pump impeller 2, the turbine runner 4, and the stator 6 gather, the impeller blades 2b of the pump impeller 2 are directed from the inlet to the outlet. Since the blade shape is designed to gradually reduce the flow passage cross-sectional area, it is possible to achieve both a reduction in torque capacity in the low speed ratio range and an improvement in torque capacity in the high speed ratio range, as well as the effect cost. Tuning can be performed according to the vehicle type and the like.

(2) The shape of the blade inner end 2c of the impeller blade 2b is set by the blade inner end 2c connecting an arbitrary point B at the inlet and a point C at the outlet with a smooth curve, and the shape is set in the torque converter with a core. Since the shapes are similar, it is possible to use the conventional proven and reliable impeller blade design method for a torque converter with a core. When manufacturing the impeller blade 2b by press molding, use the conventional mold as it is. can do.

The impeller blade designing method is described, for example, on pages 37 to 40 of "Design of Fluid Transmission" (published by Ohmsha; Tomoo Ishihara).

Although the respective embodiments have been described above with reference to the drawings, the specific configuration is not limited to the embodiments, and the present invention can be applied even if there are changes and additions without departing from the scope of the present invention. included.

[0043]

As described above, according to the present invention, in the coreless torque converter having no core at the portion where the blades of the pump impeller, the turbine runner and the stator are gathered, the impeller blades of the pump impeller are provided. To
Since the blade shape is such that the flow passage cross-sectional area gradually decreases from the inlet to the outlet, it is possible to achieve both a reduction in torque capacity in the low speed ratio range and an improvement in torque capacity in the high speed ratio range. The effect that the effect allowance can be tuned according to the type of vehicle in which the effect is installed is obtained.

[Brief description of drawings]

FIG. 1 is a sectional view showing a coreless torque converter of an embodiment of the present invention.

FIG. 2 is an end view taken along the line EF of FIG. 1 showing the shape of the impeller blades of the coreless torque converter of the embodiment.

FIG. 3 is a diagram showing a flow pattern in a low speed ratio range in the coreless torque converter of the embodiment.

FIG. 4 is a diagram showing a flow pattern in a high speed ratio range in the coreless torque converter of the embodiment.

FIG. 5 is a comparison characteristic diagram of a torque capacity coefficient, a torque ratio, and an efficiency between the coreless torque converter of the embodiment and the conventional coreless torque converter.

FIG. 6 is a cross-sectional view showing a coreless torque converter having a conventional cutout portion.

[Explanation of symbols]

 1 Converter Cover 2 Pump Impeller 2a Pump Shell 2b Impeller Blade 2c Blade Inner End 3 Turbine Hub 4 Turbine Runner 5 One Way Clutch 6 Stator

Claims (1)

[Claims] 1. A coreless torque converter that has a pump impeller, a turbine runner, and a stator, and does not have a core at a portion where these blades are gathered, in which the impeller blades of the pump impeller are directed from an inlet to an outlet. A coreless torque converter having a blade shape that gradually reduces the flow passage cross-sectional area.