JP2014126168A - Torque converter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a torque converter capable of coming into a lockup state smoothly even in a low hydraulic pressure region without causing decrease in maximum transmission torque capacity.SOLUTION: A torque converter 1 includes: a pump impeller 5; a turbine 6; a stator 7 and a lock-up piston 10. By jointing a front cover 2 and the lock-up piston 10, the pump impeller 5 and the turbine 6 come into a directly connected state. The lock-up piston 10 has a joint part 101 which is jointed to the front cover 2, and a notch part 104 extending toward an outer diameter side from an inner diameter side of the lock-up piston 10 is provided at the joint part 101. Also, at the joint part 101, a portion of the inner diameter side of the lock-up piston 10 is protruding to the front cover 2 side more than a portion of the outer diameter side.

Description

  The present invention relates to a torque converter having a lockup function.

  Conventionally, a torque converter having a lock-up function as disclosed in Patent Documents 1 to 3 below is provided. While the torque converter has a function of enabling the vehicle to start smoothly, it has a problem that it involves a reduction in power transmission efficiency. Therefore, in the prior art, after starting the vehicle, the lockup piston is pressed against the cover (lockup state), and the driving force of the engine can be transmitted directly to the output shaft, thereby reducing fuel consumption. Trying to suppress.

JP 2008-2506 A JP 2007-132659 A JP-A-7-239008

  In recent years, in order to further improve fuel efficiency, there has been a demand for an increase in the range in which the lockup state can be achieved, that is, a reduction in the vehicle speed that can be brought into the lockup state. However, if the torque converter is to be locked up in the low vehicle speed range, a control called smooth lockup control is performed to avoid engine stall and to suppress vehicle vibration, and it acts on the lockup piston. It is necessary to precisely control the pressing load.

  Here, as a measure for making it possible to precisely control the pressing load acting on the lock-up piston, it is conceivable to reduce the area of the lock-up piston to suppress the increase in the pressing load with respect to the increase in hydraulic pressure. . That is, as shown in the graph relating to the relationship between the hydraulic pressure P and the pressing load F in FIG. 5A, by reducing the area of the lock-up piston, the inclination of the graph becomes gentle and the pressing against the increase in the hydraulic pressure is performed. An increase in load can be suppressed. However, when such a measure is adopted, since the area of the lockup piston is small, the pressing load F can be sufficiently large even if the hydraulic pressure P that can be applied to the lockup piston reaches the upper limit. As a result, there is a concern that the maximum transmission torque capacity may be insufficient.

  In addition to the above-described measures, a method for improving the control characteristics of the pressing load acting on the lock-up piston by improving the controllability of the hydraulic pressure can be considered. Specifically, when it is assumed that the relationship between the control current value I applied to the adjustment valve for adjusting the hydraulic pressure and the hydraulic pressure P is proportional as shown in FIG. 5B, a solid line in the figure. As shown, the control characteristic can be improved by reducing the inclination (gradient) of the hydraulic pressure P with respect to the control current value I. However, even when such measures are taken, there is a concern that the hydraulic pressure necessary to transmit the maximum torque is insufficient.

  Based on the above-described knowledge, an object of the present invention is to provide a torque converter that can smoothly enter a lock-up state even in a low hydraulic pressure region without causing a decrease in the maximum transmission torque capacity.

  The torque converter of the present invention provided to solve the above-described problems includes a pump impeller and a turbine that are arranged to face each other, a stator disposed between the pump impeller and the turbine, and the pump impeller. The pump impeller and the turbine are directly connected by joining the lockup piston and the cover, and having a cover that can be rotated and a lockup piston disposed to face the cover. The lock-up piston has a joint part joined to the cover, and the joint part is provided with a notch part extending from the inner diameter side to the outer diameter side of the lock-up piston. And the inner diameter side portion of the lock-up piston in the joint is more than the outer diameter side portion. And it is characterized in that protrudes serial cover side.

  In the torque converter of the present invention, at the joint portion of the lock-up piston, the inner diameter side of the lock-up piston protrudes toward the cover side from the outer diameter side. Therefore, when a pressing load is applied to the lock-up piston, first, the cover and the lock-up piston come into contact with each other on the inner diameter side of the joint. This makes it possible to reduce the torque capacity sensitivity (hydraulic pressing load sensitivity) with respect to the hydraulic pressure in the low hydraulic pressure range, and to improve the control characteristics related to lockup.

  Here, as described above, when the lock-up piston is in a state of being joined to the cover on the inner diameter side of the joining portion, when the two are joined and completely sealed, it is more than the sealing portion at that time. There is a possibility that the pressing load that presses the joint portion toward the cover side does not act at the outer peripheral portion, and the outer peripheral portion cannot be joined to the cover.

  Assuming such a situation, in the torque converter of the present invention, a cut portion extending from the inner diameter side toward the outer diameter side is provided at the joint portion of the lockup piston. Thereby, even if it will be in the state joined to the cover in the inner diameter side of a joined part, it can avoid being in the state sealed completely in both joined parts. Therefore, in the torque converter of the present invention, first, after the cover and the lock-up piston come into contact with each other on the inner diameter side of the joint, the joint region between the cover and the lock-up piston is moved to the outer diameter side as the hydraulic pressure increases. The joint state between the torque converter and the cover can be changed so as to expand and eventually join the entire joint portion. That is, as the hydraulic pressure increases, the joining state of the lockup piston and the cover can be changed so that the distance (contact radius) from the rotation center of the lockup piston to the joining region increases.

  Further, as the magnitude of the pressing load acting on the lockup piston and the contact radius increase, the magnitude of the transmission torque capacity increases. Therefore, in the torque converter of the present invention, as the hydraulic pressure increases, the transmission torque capacity increases as the joint area between the cover and the lockup piston expands from the inner diameter side to the outer diameter side. As a result, the torque converter can be brought into a lock-up state even in a low vehicle speed region, which in turn contributes to improved fuel efficiency.

  In addition, by setting the cover and the lock-up piston to be joined at substantially the entire joint as described above, the maximum transmission torque capacity equivalent to that when using a lock-up piston without a notch or the like is obtained. Can be secured. Therefore, in the torque converter of the present invention, it is not necessary to use a special hydraulic control system or the like, and an increase in manufacturing cost and mass can be suppressed accordingly.

  In the above-described torque converter of the present invention, it is desirable that the cut portion is formed to be tapered from the inner diameter side to the outer diameter side of the lockup piston.

  With this configuration, after the lockup piston is joined to the case at the position on the inner diameter side of the joint, the joint region between the cover and the lockup piston expands to the outer diameter side as the hydraulic pressure increases. Can be performed more smoothly. Therefore, according to the present invention, it is possible to provide a torque converter that can be brought into a locked-up state smoothly even in a low hydraulic pressure region without causing a decrease in the maximum transmission torque capacity.

  According to the present invention, it is possible to provide a torque converter that can smoothly enter a lock-up state even in a low hydraulic pressure region without causing a decrease in the maximum transmission torque capacity.

It is sectional drawing which cut | disconnected and represented the torque converter which concerns on one Embodiment of this invention by the plane containing an axis line. (A)-(d) is explanatory drawing which showed typically the order of the operation state of the torque converter shown in FIG. It is a front view which shows the state which looked at the lockup piston used for the torque converter of FIG. 1 from the opposing surface side. 2 is a graph schematically showing the relationship between hydraulic pressure and torque capacity in the torque converter of FIG. 1. (A) is a graph for demonstrating the influence which the area of a lockup piston has on the relationship between pressing load and oil_pressure | hydraulic, (b) is the electric current sensitivity of the adjustment valve for oil pressure adjustment of control current value and oil pressure. It is a graph for demonstrating the influence which it has on a relationship.

  Hereinafter, a torque converter 1 according to an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram showing the torque converter 1, where N-N indicates the rotation center line of the output shaft 8 and the like.

  The torque converter 1 forms a hydraulic oil chamber (lubricating oil chamber) with a front cover 2 fixed to an input side (engine side) member and an impeller shell 51 fixed to an outer peripheral wall 21 of the front cover 2. Yes. The torque converter 1 includes a pump impeller 5, a turbine 6, a stator 7, and a lockup piston 10. The pump impeller 5 is connected to the crankshaft (not shown) side of the engine, and the turbine 6 is connected to the output shaft 8 to the transmission side. The pump impeller 5 and the turbine 6 are disposed to face each other, and a stator 7 is disposed between them.

  The impeller blade 52 of the pump impeller 5 is fixed in the impeller shell 51. An impeller hub 53 is integrally formed on the rotation center line side of the impeller shell 51.

  The turbine 6 includes a turbine shell 61 and a plurality of turbine blades 62 fixed in the turbine shell 61. The rotation center side end portion of the turbine shell 61 is fixed to the flange 63 a of the turbine hub 63 with a plurality of rivets 64. The turbine hub 63 is spline fitted to the output shaft 8.

  The stator 7 is disposed near the rotation center line between the pump impeller 5 and the turbine 6, is provided on the outer diameter side of the stator carrier 71 and the stator carrier 71, and is returned from the turbine 6 to the pump impeller 5. And a plurality of stator blades 72 for adjusting the direction of the hydraulic oil. The stator 7 is supported by a stator shaft 92 via a one-way clutch 9. The stator shaft 92 is fixed to a transmission housing 91.

  The lockup piston 10 is constituted by an annular plate, and is disposed between the inner surface of the front cover 2 and the outer surface of the turbine 6. The lock-up piston 10 constitutes a lock-up clutch mechanism and can rotate integrally with the output shaft 8.

  The lockup piston 10 is provided with a joint portion 101. A friction material 102 is attached to a surface (facing surface 10 a) facing the inner surface of the front cover 2 in the joint portion 101 so as to form a part of the joint portion 101. The joint portion 101 is provided on the outer peripheral portion of the lockup piston 10. The lock-up piston 10 is bent at a boundary portion 103 between the joint portion 101 and a portion on the inner diameter side of the joint portion 101 and has a substantially “<” shape in cross section. Thereby, the site | part by the side of the internal diameter of the lockup piston 10 in the junction part 101 protrudes in the front cover 2 side rather than the site | part by the side of an outer diameter.

  As shown in FIG. 3, a cut portion 104 is formed in the joint portion 101. The cut portion 104 is a concave portion formed in the facing surface 10a, and is configured by a depression or a groove. The notch 104 is formed so as to extend toward the outer diameter side with the boundary portion 103 positioned on the inner diameter side of the joint portion 101 as a base end. The front end of the notch 104 does not reach the outer peripheral end of the lock-up piston 10 and is located on the inner diameter side of the outer peripheral end. The cut portion 104 may have any shape, but is preferably formed to have a tapered shape from the inner diameter side toward the outer shape side. In the present embodiment, the cut portion 104 is a recess (groove) having a tapered shape (substantially isosceles triangle shape) in front view.

  As shown in FIG. 1, a release-side oil chamber 105 is formed between the facing surface 10 a of the lockup piston 10 and the inner surface of the front cover 2. Further, an engagement side oil chamber 106 is formed in a region opposite to the release side oil chamber 105 through the unlocking piston 10.

  The lockup piston 10 has a differential pressure (lockup differential pressure) ΔP (ΔP = hydraulic pressure in the engagement side oil chamber 106−release side) between the hydraulic pressure in the release side oil chamber 105 and the hydraulic pressure in the engagement side oil chamber 106. This is a hydraulic friction clutch that is frictionally engaged with the front cover 2 by the hydraulic pressure in the oil chamber 105, and is brought into an engaged state or a released state by controlling the differential pressure ΔP. That is, the lockup piston 10 is engaged by setting the lockup differential pressure ΔP to a positive value, and the lockup piston 10 is released by setting the lockup differential pressure ΔP to zero or less. The lockup differential pressure ΔP is applied to a lockup control valve (not shown) and an ECU (not shown) provided in a hydraulic control circuit (not shown) connected to the release side oil chamber 105 and the engagement side oil chamber 106. ).

  The torque converter 1 is provided with a mechanical oil pump 3 that is connected to and driven by a pump impeller 5. The hydraulic pressure supplied from the oil pump 3 becomes the original pressure of a hydraulic control circuit (not shown).

  Subsequently, the operation of the torque converter 1 will be described. When the vehicle speed of the vehicle becomes equal to or higher than the predetermined speed, the torque converter 1 controls a differential pressure (lock-up differential pressure) ΔP from the hydraulic pressure in the release-side oil chamber 105 and the engagement-side oil chamber 106, and the lock-up piston 10 The engaged state is established. That is, as indicated by an arrow in FIG. 2, a pressing load F toward the front cover 2 acts on the lockup piston 10, and the joint portion 101 is fastened to the inner surface of the front cover 2. As a result, the lock-up piston 10 is directly connected, and the driving force of the engine is directly transmitted to the output shaft 8.

  Here, in the torque converter 1 of the present embodiment, a characteristic operation as shown in FIGS. 2A to 2D is performed in the process in which the lock-up piston 10 is engaged. Specifically, in the initial stage (low hydraulic pressure range) in which the lockup piston 10 is engaged, the lockup piston 10 is attached to the front cover 2 as shown in FIGS. 2 (a) to 2 (b). First, the part on the inner diameter side (boundary part 103 side) of the joint part 101 comes into contact with the inner surface of the front cover 2 preferentially over the part on the outer shape side.

  As described above, in the torque converter 1 according to the present embodiment, the joint portion 101 of the lockup piston 10 is provided with the cut portion 104 that extends from the inner diameter side toward the outer diameter side. Thereby, even if it will be in the state joined to the front cover 2 in the internal diameter side of the junction part 101, it will not be in the state completely sealed in the junction part of both. That is, the oil in the release side oil chamber 105 provided between the facing surface 10a and the inner surface of the front cover 2 reaches the outer diameter side from the joint portion. As a result, a pressing load due to the differential pressure between the release side oil chamber 105 and the engagement side oil chamber 106 acts in a region on the outer diameter side of the joint portion between the joint portion 101 and the front cover 2. Therefore, even after the portion on the inner diameter side (boundary portion 103 side) of the joint portion 101 comes into contact with the inner surface of the front cover 2, as the hydraulic pressure rises, the pressing load toward the front cover 2 with respect to the joint portion 101 is increased. Works.

  When a pressing load is applied to the joint portion 101 as described above, the joint portion 101 bends to the front cover 2 side as shown in FIGS. 2B and 2C, and the joint region between the front cover 2 and the lockup piston is obtained. Gradually expands to the outer diameter side. That is, as the hydraulic pressure increases, the distance (contact radius r) from the rotation center of the lockup piston 10 to the joining region increases. After the joining portion 101 starts to be joined to the front cover 2 in this way, when the whole joining portion 101 is joined to the inner surface of the front cover 2 as shown in FIG. The piston 10 is completely engaged (lock-up state). Thereby, the transmission torque capacity of the torque converter 1 reaches the maximum value.

  As described above, in the torque converter 1 of the present embodiment, the joint portion 101 of the lockup piston 10 has a structure in which the inner diameter side of the lockup piston 10 protrudes toward the front cover 2 rather than the outer diameter side. Therefore, when a pressing load is applied to the lockup piston 10, first, the front cover 2 and the lockup piston 10 come into contact with each other on the inner diameter side portion of the joint portion 101. This makes it possible to reduce the torque capacity sensitivity (hydraulic pressing load sensitivity) with respect to the hydraulic pressure P in the low hydraulic pressure region as shown in FIG. 4 and to improve the control characteristics related to lockup. Moreover, according to the torque converter 1, it becomes possible to be in a lock-up state even in a low vehicle speed region, and the fuel efficiency of the vehicle can be improved.

  Further, in the torque converter 1 of the present embodiment, the joint portion 101 of the lockup piston 10 is provided with a cut portion 104 that extends from the inner diameter side toward the outer diameter side. Accordingly, even when the joint portion 101 is joined to the front cover 2 on the inner diameter side of the joint portion 101 as shown in FIG. 2A, it can be avoided that the joint portion 101 is completely sealed. . Therefore, in the torque converter 1, as shown in FIG. 2A, first, the front cover 2 and the lockup piston 10 come into contact with each other on the inner diameter side portion of the joint portion 101, and then the hydraulic pressure P increases as shown in FIG. As shown in FIGS. 2B and 2C, the joining area between the front cover 2 and the lock-up piston 10 expands to the outer diameter side, and eventually joins the entire joining portion 101 as shown in FIG. That is, as the hydraulic pressure P increases, the distance (contact radius r) from the rotation center of the lockup piston 10 to the joining region increases. As a result, as shown in FIG. 4, as the hydraulic pressure P increases, the size of the transmission torque capacity increases as the joining region between the front cover 2 and the lockup piston 10 expands from the inner diameter side to the outer diameter side. .

  In the torque converter 1, the front cover 2 and the lockup piston 10 can be reliably joined in substantially the entire joint portion 101. Therefore, the lockup state can be achieved even in the low vehicle speed region without causing a decrease in the maximum transmission torque capacity. Moreover, according to the torque converter 1, it is not necessary to use a special hydraulic pressure P control system or the like, and an increase in manufacturing cost and mass can be suppressed accordingly.

  In the torque converter 1 of the present embodiment, the notch 104 is formed so as to taper from the inner diameter side to the outer diameter side of the lockup piston 10. With such a configuration, it is possible to smoothly perform the joining operation of the lockup piston 10 as shown in FIGS.

  In the present embodiment, an example in which the cut portion 104 is a recess having a tapered shape (substantially isosceles triangle shape) when viewed from the front is shown, but the present invention is not limited to this, and for example, a lock-up A groove or the like extending linearly or curvedly from the inner diameter side to the outer diameter side of the piston 10 may be used. Further, in the case where the notch 104 is tapered, the joining area and the contact radius between the lock-up piston 10 and the front cover 2 are adjusted by adjusting the taper angle and the position where the tip of the notch 104 reaches. The rate of change of r can be adjusted and optimized.

DESCRIPTION OF SYMBOLS 1 Torque converter 2 Front cover 5 Pump impeller 6 Turbine 7 Stator 10 Lockup piston 101 Joint part 104 Cut part

Claims (2)

A pump impeller and a turbine arranged facing each other;
A stator disposed between the pump impeller and the turbine;
A cover that is rotatable with the pump impeller;
A lock-up piston arranged to face the cover;
Have
By joining the lock-up piston and the cover, the pump impeller and the turbine are directly connected,
The lock-up piston has a joint joined to the cover;
The joint is provided with a notch extending from the inner diameter side of the lock-up piston toward the outer diameter side,
The torque converter according to claim 1, wherein a portion on the inner diameter side of the lock-up piston protrudes toward the cover side from a portion on the outer diameter side in the joint portion.   2. The torque converter according to claim 1, wherein the cut portion is formed to be tapered from an inner diameter side to an outer diameter side of the lockup piston.

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