JP4145707B2 - Belt type continuously variable transmission - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a belt type continuously variable transmission in which a belt is suspended between a fixed pulley and a movable pulley.
[0002]
[Prior art]
As is well known, a belt type continuously variable transmission has a belt-like power transmission element such as a metal belt or chain spanned between a primary pulley and a secondary pulley, and movable pulleys provided on both pulleys are movable. By making the pulley groove width variably set by operating the hydraulic pressure supplied to the hydraulic chamber attached to the pulley, the winding diameter of the power transmission element to the primary pulley and the secondary pulley is changed, and the gear ratio is made steplessly Variable.
[0003]
That is, the primary pulley has a fixed pulley fixed to the primary shaft and a movable pulley that is slidably mounted on the primary shaft in the axial direction and rotates together with the primary shaft, and the movable pulley slides in the axial direction. As a result, the pulley groove width changes. Similarly, the secondary pulley has a fixed pulley fixed to the secondary shaft and a movable pulley that is slidably mounted on the secondary shaft in the axial direction and rotates together with the secondary shaft, and the movable pulley slides in the axial direction. As a result, the pulley groove width changes. Each fixed pulley is also called a fixed sheave, and each movable pulley is also called a movable sheave.
[0004]
In such a belt type continuously variable transmission, it is effective to reduce the weight around the rotation shaft in order to improve the speed change quality. For example, Japanese Utility Model Laid-Open No. 6-32805 discloses a rotation speed. A technique for reducing the weight by forming a hollow shaft is disclosed.
[0005]
[Patent Document 1]
Japanese Utility Model Publication No. 6-32805 [0006]
[Problems to be solved by the invention]
However, the torque capacity of the belt depends on how the cone surface of the pulley is supported. Conventionally, the cone surface is prevented from falling by increasing the thickness of the joint between the shaft and the cone surface, and the torque capacity is reduced. I try to suppress the decline. For this reason, even if the shaft is formed hollow, it is not only difficult to reduce the weight of the entire rotating part including the shaft and pulley, but also the rigidity of each part becomes non-uniform, which improves the transmission quality. It was an obstacle.
[0007]
The present invention has been made in view of the above circumstances, and it is possible to reduce the weight of the entire rotating part including the shaft and the pulley while ensuring the necessary rigidity, and to make the rigidity of each part uniform. The object is to provide a step transmission.
[0008]
[Means for Solving the Problems]
To achieve the above object, the present invention provides a fixed pulley formed integrally with a hollow rotating shaft, and is mounted on the rotating shaft so as to be slidable in the axial direction so as to face the fixed pulley. A belt-type continuously variable transmission in which a belt is suspended between a movable pulley and a cone pulley on the back side of the cone surface of the fixed pulley with an outermost belt suspension position and an innermost belt suspension position of the cone surface. A hollow portion is provided on the inner side from the center, and a suspension portion for connecting the back side of the cone surface and the rotary shaft is provided on the outer side of the hollow portion, and the rotation of the suspension portion is provided inside the rotary shaft. A partition wall located at the connecting portion to the shaft and a partition wall located on the cone surface side of the fixed pulley are provided.
[0009]
At this time, as the movable pulley, it is desirable to employ a movable pulley provided with a lightening portion at the base portion on the back side of the cone surface.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. 1 to 3 relate to an embodiment of the present invention, FIG. 1 is a skeleton diagram showing a power transmission system of a continuously variable transmission, FIG. 2 is an enlarged view of a main part on the secondary pulley side, and FIG. It is a principal part enlarged view which shows a modification.
[0011]
In FIG. 1, reference numeral 1 denotes an engine, and an output shaft 2 of the engine 1 is connected to a drive shaft 6 that supports a drive wheel 5 via a continuously variable transmission unit 3 and a final reduction unit 4 that constitute a continuously variable transmission. It is connected continuously. The continuously variable transmission unit 3 includes a torque converter 7, a forward / reverse switching device 8, and a continuously variable transmission 9 from the input side. The output shaft 2 of the engine 1 is connected to the impeller 7 a of the torque converter 7. A turbine 7 b of the torque converter 7 is connected to the planetary input shaft 8 a of the forward / reverse switching device 8.
[0012]
Reference numeral 10 denotes a drive sprocket that is disposed between the torque converter 7 and the forward / reverse switching device 8 and is pivotally attached to the impeller 7 a of the torque converter 7, and the chain 11 wound around the drive sprocket 10. The oil pump housed in an oil pan (not shown) is driven via
[0013]
The forward / reverse switching device 8 includes a planetary gear 12, a forward clutch 13, and a reverse brake 14, and is in a neutral state when both the forward clutch 13 and the reverse brake 14 are in an open state. In addition, when only the forward clutch 13 is engaged, the planetary gear 12 rotates integrally, and the power from the turbine 7 b of the torque converter 7 is transmitted to the continuously variable transmission 9 as it is. On the other hand, when the forward clutch 13 is released and the reverse brake 14 is engaged, the continuously variable transmission (belt type continuously variable transmission) with the power from the turbine 7b of the torque converter 7 reversed via the planetary gear 12. 9 is transmitted.
[0014]
The continuously variable transmission 9 is wound around a primary pulley 15 that is pivotally attached to a primary shaft 9a, a secondary pulley 16 that is opposed to the primary pulley 15 and is pivotally attached to a secondary shaft 9b, and both pulleys 15 and 16. The secondary shaft 9b is connected to the differential device 4b that is attached to the drive shaft 6 via the reduction gear train 4a of the final reduction gear 4.
[0015]
The primary pulley 15 includes a fixed sheave (fixed pulley) 20 that is integrally formed with the primary shaft 9a, and a movable sheave (movable pulley) 21 that is opposed to the fixed sheave 20 and that is movable in the axial direction. A cup-shaped cylinder 22 fixed to the primary shaft 9a on the back side of the movable sheave 21, and a plunger 23 fixed to the movable sheave 21 and slidable in the axial direction within the cylinder 22. Thus, a primary hydraulic chamber 9c is formed. A cover 24 having an opening at the center is attached to the open end side of the cylinder 22, and a balance chamber 25 for canceling the centrifugal hydraulic pressure of the primary hydraulic chamber 9 c between the cover 24 and the back side of the plunger 23. Is formed.
[0016]
Similarly, the secondary pulley 16 also includes a fixed sheave 30 that is integrally formed with the secondary shaft 9b, and a movable sheave 31 that is opposed to the fixed sheave 30 and that is engaged in an axial direction so as to be movable back and forth. A secondary hydraulic pressure is provided by a cup-shaped cylinder 32 fixed to the movable sheave 31 and a plunger 33 fixed to the secondary shaft 9b and slidably disposed in the axial direction in the cylinder 32 on the back side of the shaft 31. A chamber 9d is formed. A cover 34 having an opening at the center is attached to the open end side of the cylinder 32, and a balance chamber 35 for canceling the centrifugal hydraulic pressure of the secondary hydraulic chamber 9 d between the cover 34 and the back side of the plunger 33. Is formed.
[0017]
The line pressure obtained by adjusting the discharge pressure of the oil pump is supplied to the secondary hydraulic chamber 9d provided in the secondary pulley 16, and the primary pressure obtained by reducing the line pressure is supplied to the primary hydraulic chamber 9c provided in the primary pulley 15. Is done. As a result, due to the operating pressure supplied to the hydraulic chambers 9c and 9d, tension necessary for torque transmission is applied to the drive belt 17 via the movable sheaves 21 and 31, and the groove widths of the pulleys 15 and 16 are variably set. Thus, the gear ratio is controlled.
[0018]
In such a continuously variable transmission 9, the pulley needs to have rigidity for holding the belt in a predetermined position, and the pulley itself needs to be lightened in order to improve the shift response. However, simply reducing the thickness by removing a thick portion that does not affect the rigidity causes non-uniform rigidity and is not necessarily effective.
[0019]
For this reason, in the present invention, by removing unnecessary thick portions from the primary pulley 15 and the secondary pulley 16 and at the same time applying appropriate reinforcement, uniform rigidity and light weight can be achieved while ensuring rigidity. Is to be realized. Hereinafter, taking the secondary pulley 16 as an example, a specific configuration for uniform rigidity and weight reduction will be described. Although the secondary pulley 16 will be described here, the same applies to the primary pulley 15.
[0020]
As shown in FIG. 2, the secondary pulley 16 includes a fixed sheave 30 formed by joining a plurality of members, and a movable sheave 31 in which the thick portion of the cone surface base is thinned, and is configured as a secondary shaft. A movable sheave 31 is coupled to a shaft portion of a fixed sheave 30 forming 9b by a spline (ball spline or normal spline) so as to be movable back and forth in the axial direction.
[0021]
The movable sheave 31 is provided with an annular groove 31b having a substantially rectangular cross section in the thick part of the base of the cone disk 31a forming the cone surface, and the seal width with the secondary shaft 9b is reduced to the minimum necessary to reduce the weight. On the other hand, the fixed sheave 30 is formed by integrally connecting three members in the present embodiment, and performs unneeded portions and necessary reinforcement.
[0022]
The members constituting the fixed sheave 30 are a cone disk 40 that forms a cone surface for suspending the drive belt 17, and are integrally coupled to the back side of the cone disk 40 to reinforce the cone surface and the shaft of the secondary shaft 9b. The first shaft 41 that forms the end side and the second shaft 42 that is coupled to the cone disk 40 and forms the output end side of the secondary shaft 9b, and each member is selected as a material suitable for the required strength and mutual coupling. And formed in advance by forging or the like.
[0023]
The cone disc 40 is a member having a shaft portion 40a that forms a part of the secondary shaft 9b and a cone portion 40b that is expanded in a cone shape from the shaft portion 40a. The shaft portion 40a is located at the base of the cone portion 40b. A hollow cylinder is formed on both sides of the partition wall 40c provided in the corresponding part, and the diameter of the hollow part on the cone surface side is formed larger than the diameter of the hollow part on the back side of the cone surface.
[0024]
An annular protrusion 40d is provided on the cone surface back side of the cone portion 40b. The annular protrusion 40d is joined to a flange portion 41b of the first shaft 41 described below, and serves to reinforce the thrust force acting on the cone portion 40b. It is provided at a position where the deflection rigidity of the cone part 40b is substantially equal between the position of the outer end and the position of the innermost end.
[0025]
The first shaft 41 is a member having a flange portion 41b that is widened obliquely upward from a shaft portion 41a that forms part of the secondary shaft 9b, and the shaft portion 41a has the same outer diameter as the shaft portion 40a of the cone disk 40. Thus, it is hollowed out in a hollow cylindrical shape on both sides of the partition wall 41c provided at a portion corresponding to the base portion of the flange portion 41b. The diameter of the hollow part on both sides of the partition wall 41c is substantially the same as the diameter of the hollow part on the back side of the cone surface in the shaft part 40a of the cone disk 40.
[0026]
The second shaft 42 is a shaft member having the same outer diameter as the shaft portion 40a of the cone disk 40 and the shaft portion 41a of the first shaft 41, and has a predetermined length for sealing the secondary hydraulic chamber 9d with the movable sheave 31. A spline groove is formed on the outer periphery through which the movable sheave 31 is engaged via the cylindrical portion. The plunger 33 described above is fixed to the end portion of the spline groove.
[0027]
Further, the second shaft 42 is thinned at the end to be joined to the cone disk 40 with substantially the same diameter as the hollow portion of the shaft portion 40a, and the thinned portion is separated by the partition wall 42a. A hydraulic passage 42b is formed in the front (output side) in the axial direction. The partition wall 42 a is disposed so as to be in the vicinity of the innermost end suspension position of the drive belt 17. In the middle of the hydraulic passage 42b, an oil hole 42c is formed in the radial direction so as to communicate with the secondary hydraulic chamber 9d.
[0028]
The cone disk 40, the first shaft 41, and the second shaft 42 are integrally joined to each other by, for example, friction welding (friction welding) to form the fixed sheave 30. In the joining of the respective members by the friction welding, the end surface of the shaft portion 41a of the first shaft 41 is brought into contact with the end surface of the shaft portion 40a on the cone-side back surface of the cone disk 40, and the first projection portion 40d of the cone portion 40b is first contacted. By contacting the front end surface of the flange portion 41b of the shaft 41 and rotating while pressing in the axial direction, the respective contact surfaces generate heat due to frictional heat and are softened, and the portions of the respective contact surfaces are integrated in a metal structure. And joined in a solid state. Similarly, the end surface of the second shaft 42 is brought into contact with the end surface of the shaft portion 40a on the cone surface side of the cone disk 40, and is rotated while being pressed in the axial direction to join the metal structure by frictional heat.
[0029]
In the friction welding, burrs called flash are generated from the joining surface, that is, the pressure welding surface, on both sides in the radial direction of the pressure welding surface, and joining is also achieved at the flash portion. The flash generated on the outer periphery of the joint between the protrusion 40d and the flange 41b and the flash generated on the outer periphery of the joint between the shaft 40a and the second shaft 42 are removed after the friction welding process.
[0030]
Accordingly, the fixed sheave 30 has a circular secondary shaft 9b having the same outer diameter, and an annular space 50 is formed on the back side of the cone surface around the base portion of the cone disk 40. Within the secondary shaft 9b, a space 51 is formed by the partitions 40c and 41c and a space 52 is formed by the partitions 40c and 42a. At the same time, the cone surface side base portion of the cone disk 40 is suspended and reinforced by the partition walls 40c and 42a in the secondary shaft 9b, and the cone surface rear side is suspended and reinforced by the flange portion 41b and the secondary shaft 9b. The base portion of the formed suspension is suspended and reinforced by the partition wall 41c in the secondary shaft 9b.
[0031]
That is, on the back side of the cone disk 40, a lightening portion by the space portion 50 is formed inside the radial center, and a reinforcing suspension portion by the flange portion 41b is formed outside the lightening portion. Therefore, the bending rigidity of the cone portion 40b is made substantially equal at the outermost end and the innermost end of the belt suspension position with respect to the axial load acting on the cone disk 40, that is, the thrust force, and the cone surface is less tilted. can do.
[0032]
In addition, the secondary shaft 9b is formed in a hollow circular tube having the same outer diameter, the partition 41c that opposes bending stress acting on the secondary shaft 9b via the flange portion 41b inside the secondary shaft 9b, and the cone portion 40b by the thrust force. Since the partition walls 40c and 42a are provided to counter the bending stress generated in the secondary shaft 9b by the bending stress and radial force generated in the shaft, the bending rigidity of the cone disk 40 and the bending rigidity of the secondary shaft 9b can be simultaneously improved. Can do.
[0033]
The two partition walls 40c and 42a provided in the secondary shaft 9b around the base of the cone disk 40 can be replaced with one side wall. That is, as shown in FIG. 3, the shaft portion 40a of the cone disk 40 is slightly extended toward the cone surface side so that the partition wall 40c is provided at a substantially intermediate position between the partition walls 40c and 42a, and the partition wall 42a of the second shaft 42 is eliminated. You may do it.
[0034]
In addition, since the fixed sheave 30 is formed by pre-molding a plurality of parts by forging or the like and then joined by friction welding or the like, the shape of the lightening portion can be set with a high degree of freedom and manufactured at low cost. be able to. Furthermore, the optimal characteristic according to load can be given by selecting the material of each member which comprises the fixed sheave 30 (and secondary shaft 9b) suitably.
[0035]
The same applies to the movable sheave 31. By reducing the seal width with respect to the secondary hydraulic chamber 9d to the minimum necessary and performing the lightening by the annular groove 31b having a substantially rectangular cross section, the cone disk 31a is secured while achieving light weight. can do.
[0036]
As described above, in the present embodiment, unnecessary portions are thinned and necessary reinforcement is simultaneously performed, the weight of the entire rotating portion is reduced while ensuring sufficient rigidity, and the rigidity of each portion is increased. Uniformity can be achieved, and transmission quality can be improved.
[0037]
【The invention's effect】
As described above, according to the present invention, it is possible to reduce the weight of the entire rotating part including the shaft and the pulley while ensuring the necessary rigidity, and to make the rigidity of each part uniform, thereby improving the transmission quality. Can contribute.
[Brief description of the drawings]
FIG. 1 is a skeleton diagram showing a power transmission system of a continuously variable transmission. FIG. 2 is an enlarged view of a main part on a secondary pulley side. FIG. 3 is an enlarged view of a main part showing a modification of FIG.
9 continuously variable transmission 9a primary shaft 9b secondary shaft 15 primary pulley 16 secondary pulley 17 drive belt 20, 30 fixed sheave 21, 31 movable sheave 40b cone portion 41b flange portions 40c, 41c, 42a partition walls 50, 51, 52 space portion

Claims (2)

A belt is suspended between a fixed pulley formed integrally with a hollow rotating shaft and a movable pulley facing the fixed pulley and slidably mounted on the rotating shaft in the axial direction. A belt type continuously variable transmission,
On the back side of the cone surface of the fixed pulley, a thinning portion is provided inside the center of the outermost belt suspension position and the innermost belt suspension position of the cone surface, and the cone surface is disposed outside the thinning portion. Provide a suspension that connects the back side and the rotating shaft,
A belt type continuously variable transmission characterized in that a partition wall located at a connecting portion of the suspension portion to the rotation shaft and a partition wall located on the cone surface side of the fixed pulley are provided inside the rotation shaft. . 2. The belt type continuously variable transmission according to claim 1, wherein a thinning portion is provided at a base portion on the back side of the cone surface of the movable pulley.

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