JP2016169843A - Continuously variable transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a continuously variable transmission which can reduce a pump loss by obtaining a capacity coping with loading pressure from a high-pressure side up to a low-pressure side by using one pump, and can suppress an increase of weight and a high cost.SOLUTION: Since a capacity variable vane pump 100 has a hydraulic pressing device 80 for pressing an input-side disc 2 at desired loading pressure by an output-side disc 3A so as to grip a power roller 11, and the pump for supplying oil to the pressing device 80 is variable in capacity according to the loading pressure, a capacity coping with the loading pressure from a high-pressure side up to a low-pressure side can be obtained by one pump 100. Accordingly, a pump loss can be reduced, and an increase of weight and a high cost can be suppressed.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a continuously variable transmission such as CVT or IVT that can be used in transmissions of automobiles and various industrial machines.

  Toroidal type continuously variable transmissions have been studied and partially implemented as automatic transmissions for automobiles. The toroidal continuously variable transmission has a plurality of power rollers sandwiched between axial side surfaces of an input side disk and an output side disk that are arranged concentrically and rotate relative to each other, and through these power rollers, Power is transmitted from the input side disk to the output side disk. Then, the gear ratio between these two disks is adjusted by changing the inclination angle of each of these power rollers. During operation of such a toroidal-type continuously variable transmission, an oil film of traction oil is formed on the rolling contact portion (traction portion) between the axial side surface of both discs and the peripheral surface of each power roller. Power is transmitted between them via this oil film. In the toroidal type continuously variable transmission, in order to ensure the power transmission through such an oil film, a pressing device is provided to press the disks in a direction approaching each other.

As such a pressing device, a loading cam type pressing device which is a mechanical type is generally used. However, the use of a hydraulic pressing device has been studied and widely known.
Among these, the loading cam type pressing device mechanically generates a pressing force proportional to the magnitude of the transmission torque, and therefore has an advantage that power is not particularly consumed when the pressing device is operated. However, since the magnitude of the torque to be transmitted and the required pressing force are not necessarily proportional, the loading cam type pressing device alone is not related to changes in operating conditions (temperature of traction oil, gear ratio, etc.) The surface pressure of each traction section cannot always be maintained at an appropriate value. Specifically, the pressing force generated by the loading cam type pressing device is sufficiently large (a toroidal-type continuously variable) in order to surely prevent an excessive slip called a gross slip from occurring in each of these traction portions. If the maximum pressing force required during the operation of the transmission is regulated), the surface pressure of each of the traction sections may be excessive depending on the driving condition, and the transmission efficiency and durability of the toroidal continuously variable transmission will be reduced.

On the other hand, in the case of a hydraulic pressing device, power is consumed to operate the pump for generating hydraulic pressure instead of generating an appropriate pressing force according to the operating situation. As a result, the overall efficiency of the toroidal type continuously variable transmission decreases.
The loading pressure required to press the disks in the direction approaching each other varies depending on the operating conditions, but in order to cope with the loading pressure from the high pressure side to the low pressure side with a single pump, a high loading pressure is required. Although a corresponding pump is required, the relationship between the required loading pressure and the required pump capacity tends to increase the required pump capacity when the loading pressure is high, as shown in FIG.
Therefore, in order to cope with the loading pressure from the high pressure side to the low pressure side with one pump, it is necessary to use a pump with a large pump capacity, and thus the pump loss increases. Here, the pump loss refers to the power used by the pump among the power generated by the engine.
The power L required for the pump can be expressed as L (kw) = P · Q / 60η.
P is the protrusion pressure (MPa) of the pump, Q is the discharge flow rate (l / min), and η is the pump efficiency.
Therefore, by reducing the discharge flow rate Q, the power L used for the pump can be reduced. However, if a large flow rate is not required, that is, when a high loading pressure is not required, an excessive flow rate is required. Is discharged from the pump, resulting in a large pump loss.

For this reason, it is conceivable to reduce pump loss by using two pumps having different capacities in order to cope with the loading pressure from the high pressure side to the low pressure side.
Patent Document 1 describes that by providing a high-pressure pump and a low-pressure pump, respectively, the friction loss of a bearing that receives a load caused by the operation of the transmission is reduced, the life is extended, and the pump loss is reduced. Has been.
Patent Document 2 describes that in a toroidal-type continuously variable transmission, two oil pumps are used to switch the discharge flow rate between two stages of a small capacity and a large capacity.

Japanese Utility Model Publication No. 6-37224 JP 2010-249300 A

However, when two pumps having different capacities are provided to cope with the loading pressure from the high pressure side to the low pressure side, the weight of the continuously variable transmission increases and the cost also increases.
Patent Documents 1 and 2 do not disclose anything about reducing pump loss with a single pump.

  The present invention has been made in view of the above circumstances, and it is possible to reduce the pump loss by obtaining a capacity for accommodating the loading pressure from the high pressure side to the low pressure side with a single pump, while increasing the weight and cost. It aims at providing the continuously variable transmission which can be suppressed.

In order to achieve the above object, a continuously variable transmission according to the present invention includes an input side disk and an output side disk that are concentrically and rotatably provided with their inner surfaces facing each other. A continuously variable transmission having a power roller sandwiched between both disks and a hydraulic pressing device that presses at least one of the disks with a desired loading pressure so as to sandwich the power roller. In
The pump for supplying oil to the pressing device is a variable displacement pump whose capacity can be changed according to the loading pressure.

  In the present invention, since the pump for supplying oil to the pressing device is a variable displacement pump whose capacity can be changed according to the loading pressure, this one pump (variable displacement pump) can be used from the high pressure side to the low pressure side. The capacity to cope with the loading pressure is obtained. Therefore, pump loss can be reduced, and an increase in weight and cost can be suppressed.

  In the above configuration of the present invention, the variable displacement pump is preferably a variable displacement vane pump or a variable displacement piston pump.

  Since the variable displacement pump is a variable displacement vane pump or a variable displacement piston pump, from a high pressure side to a low pressure side by reducing the pump capacity when the loading pressure is small and increasing the pump capacity when the loading pressure is large. The pump capacity to cope with the loading pressure can be easily obtained.

  According to the present invention, the pump for supplying oil to the pressing device is a variable displacement pump whose capacity can be changed according to the loading pressure, so that one pump can cope with the loading pressure from the high pressure side to the low pressure side. As a result, a pump loss can be reduced, and an increase in weight and cost can be suppressed.

1 is a sectional view showing a toroidal continuously variable transmission according to an embodiment of the present invention. FIG. 2 shows a schematic configuration of a pump that supplies oil to the pressing device, where (a) is a cross-sectional view showing a case where the loading pressure is low, and (b) is a cross-sectional view showing a case where the loading pressure is high. FIG. 2 is a hydraulic circuit diagram provided with a variable displacement vane pump. Another embodiment of the present invention is shown and is a diagram showing a schematic configuration of a variable displacement piston pump. It is a graph which shows the relationship between required loading pressure and required pump capacity.

Hereinafter, embodiments of a continuously variable transmission according to the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view showing a half-toroidal continuously variable transmission as an example of a continuously variable transmission. This half-toroidal continuously variable transmission includes an input shaft 1, input disks 2 and 2, output disk 3A, an outer peripheral gear 4A provided on the outer peripheral surface of the output disk 3A, upper and lower yokes 23A and 23B, trunnion The power roller 11, the driving device 32, the hydraulic pressing device 80, the upper plate 52, and the like are integrally assembled to form a variator module 43. The variator module 43 is housed and attached in a casing (not shown). Yes.

  In such a variator module 43, the lower spherical post 68 fixed to the upper cylinder body 61 and the lower cylinder body 62 constituting the driving cylinder 31 of the driving device 32, and the upper spherical post 68 fixed to the upper plate 52. The spherical post 64 is a columnar post 69 integrally joined in the vertical direction. In the variator module 43, the pair of columnar posts 69 are the upper plate 52 and the cylinder body (the upper cylinder body 61 and the lower cylinder body 62) of the drive cylinder 31. ) Is connected.

Further, the input shaft 1 penetrates through the upper and lower central portions of the columnar post 69. A pair of input side disks 2 and 2, an output side disk 3 </ b> A, a pressing device 80, and the like are supported on the input shaft 1.
The output side disk 3A is supported by the input shaft 1 via a radial needle bearing 35 so as to be relatively rotatable.
Further, an output side disk 3A is disposed between the pair of columnar posts 69, and the output side disk 3A is axially positioned at both ends of the output side disk 3A in the axial direction and is supported so as to be rotatable around the axis. A bearing 55 is provided. That is, the thrust ball bearing 60 is disposed between the columnar post 69 and the small-diameter side end portion of the output side disk 3A, and the position along the axial direction of the input shaft 1 of the output side disk 3A is regulated, and the output The side disk 3A is allowed to rotate around the axis.

  The pressing device 80 includes a first cylinder portion 81 coupled to the left end portion of the input shaft 1, a second cylinder portion 82 provided on the input side disk 2, an annular first piston portion 83, and an annular shape The second piston portion 84 is provided.

A space surrounded by the inner surface of the first cylinder portion 81, the first piston portion 83, and a part of the outer peripheral surface of the input shaft 1 constitutes a first hydraulic chamber 85.
In addition, the space surrounded by the inner peripheral surface of the second cylinder portion 82, the second piston portion 84, the back surface 2d of the input side disk 2, and a part of the outer peripheral surface of the input shaft 1 is a second space. The hydraulic chamber (oil chamber) 90 is configured.

  In addition, a disc spring 94 for applying a preload is inserted between the first piston portion 83 and the first cylinder portion 81 by partially using the first hydraulic chamber 85, The first piston portion 83 that is movable along the input shaft 1 is urged toward the input side disk 2 with respect to the cylinder portion 81.

In such a pressing device 80, pressure oil of a predetermined pressure is fed into the first hydraulic chamber 85 and the second hydraulic chamber 90. Then, a force is generated in the hydraulic chambers 85 and 90 in the direction in which the axial dimensions of the hydraulic chambers 85 and 90 increase.
When the pressure oil is fed into the first hydraulic chamber 85, the first piston portion 83 is pressed to the right side (input side disk 2 side) in FIG. 1, thereby being integrally formed on the back surface of the input side disk 2. The input side disk 2 is pressed to the right side through the second cylinder portion 82.

On the other hand, when the pressure oil is fed into the second hydraulic chamber 90, the movement of the second piston portion 84 to the left side in FIG. 1 is restricted, so that the input side disk 2 is pressed to the right side.
The forces generated in both the hydraulic chambers 85 and 90 in this way press the input side disk 2 toward the output side disk 3A. Therefore, the traction part of the power roller 11 is brought into rolling contact with both the input / output side disks 2 and 3, and the rotational driving force of the input side disk 2 is transmitted to the output side disk 3 at a desired reduction ratio.

FIG. 2 is a cross-sectional view showing a schematic configuration of a pump 100 that supplies oil to a pressing device 80 that presses the input side disk 2 toward the output side disk 3A with a desired loading pressure. FIG. (B) shows the case where the loading pressure is high.
The pump 100 is a variable displacement vane pump 100 whose capacity can be changed according to the loading pressure. The variable displacement vane pump 100 includes a vane pump main body 110 and a cylinder device 120.
The vane pump main body 110 includes a casing 111, a ring 112, a rotor 113, and a vane 114.
A ring 112 having a circular cross section is housed in a housing section 111 a having a circular cross section of the casing 111. The diameter of the ring 112 is smaller than the diameter of the accommodating part 111a, and it can move within the accommodating part 111a.

A rotor 113 is provided on the inner side of the ring 112 so as to be rotatable around its center and eccentric with respect to the ring 112. The rotor 113 is provided in a fixed state in the accommodating portion 111a of the casing 111, and the rotor 113 is rotationally driven using the engine as a drive source.
A plurality of grooves extending in the radial direction are provided in the rotor 113 at predetermined intervals in the circumferential direction. A vane 114 is slidably inserted into each groove, and the tip of the vane 114 is the outer periphery of the rotor 113. It protrudes from the surface. The vane 114 is moved in the radial direction by the centrifugal force generated by the rotation of the rotor 113, and rotates together with the rotor 113 while being in sliding contact with the inner peripheral surface of the ring 112.

  2, the volume of the space surrounded by the vane 114, the ring 112, and the rotor 113 increases with the rotation of the rotor 113 (clockwise rotation in FIG. 2). Therefore, the oil is sucked in, and the volume of the space surrounded by the vane 114, the ring 112, and the rotor 113 below the line segment XX ′ is the rotation of the rotor 113 (clockwise in FIG. 2). Therefore, the oil is discharged.

Further, a recess 111b is provided along the line XX 'on the inner peripheral surface of the casing 111, and a spring 116 is accommodated in the recess 111b in a compressed state. One end of the spring 116 is in contact with the ring 112, and the ring 112 is urged to the left in FIG. 2 by the urging force of the spring 116.
On the other hand, the cylinder device 120 is located on the opposite side of the spring 116 with the ring 112 interposed therebetween, and the tip of the piston 120a of the cylinder device 120 penetrates the insertion hole 111c provided in the casing 111 so as to be slidable. The ring 112 is in contact with the ring 112. A seal ring 117 is provided on the outer periphery of the piston rod of the piston 120a.
A loading pressure is applied to the cylinder 120b of the cylinder device 120.

The position of the ring 112 in the direction of the line segment XX ′ is determined by the relationship between the piston pressure acting on the piston 120a by the loading pressure and the urging force of the spring 116.
Therefore, when the loading pressure increases, as shown in FIG. 2B, the ring 112 is pushed toward the spring 116 against the biasing force of the spring 116 by the piston 120a, and the pump capacity increases.
On the other hand, when the loading pressure decreases, the ring 112 is pushed toward the piston 120a by the biasing force of the spring 116, as shown in FIG.
Here, even if the ring 112 is pushed to the side where the pump capacity is small (the left side in FIG. 2A) by the urging force of the spring 116, the casing 111 is accommodated so that the necessary minimum pump capacity can be secured. By designing the positional relationship between the inner wall of the portion 111a and the central axis of the rotor 113, a minimum pump capacity can be secured.

FIG. 3 is a hydraulic circuit diagram provided with the variable displacement vane pump 100. In this figure, the loading piston 130 corresponds to the piston portions 83 and 84 shown in FIG.
The loading cylinder 131 that accommodates the loading piston 130 and the cylinder 120b of the cylinder device 120 that constitutes the variable displacement vane pump 100 are connected by an oil passage 132, and the loading cylinder 131 and the vane pump main body 110 that constitutes the variable displacement vane pump 100; Are connected by an oil passage 133.
The oil passage 133 is connected to the discharge port of the vane pump main body 110, and a loading pressure adjustment valve 135 is provided in the middle of the oil passage 133. The oil discharged from the discharge port is supplied to the loading cylinder 131 after the hydraulic pressure is adjusted by the loading pressure adjustment valve 135. The loading cylinder 131 corresponds to the cylinder portions 81 and 82 shown in FIG.
The suction port of the vane pump main body 110 is connected to the oil pan 137 by an oil passage 136.

  Note that the variable displacement vane pump 100 and the later-described variable displacement piston pump 150 not only supply oil to the loading cylinders 131 and 152 but also drive used to move the trunnion in the axial direction, for example. Oil is supplied through a predetermined oil passage to the cylinder 31, the traction surface where the disks 2, 3A and the power roller contact, various bearings, and the like.

  In the toroidal type continuously variable transmission including the variable displacement vane pump 100, the rotor 113 of the variable displacement vane pump 100 is rotated by using the engine as a drive source, so that the oil in the oil pan 137 is sucked from the suction port. After being discharged from the discharge port, the pressure is adjusted by the loading pressure adjusting valve 135, and then supplied to the loading cylinder 131. As a result, the loading piston 130 is pressed and pressed against the power roller 11 by pressing the input side disk 2 toward the output side disk 3A with a desired loading pressure.

At this time, since the loading cylinder 131 and the cylinder 120b are connected by the oil passage 132, this loading pressure acts on the cylinder 120b.
Therefore, when the input side disk 2 is pressed against the power roller 11 with a strong force, if the loading pressure increases, the ring 112 is springed against the biasing force of the spring 116 by the piston 120a as shown in FIG. It is pushed to the 116 side, and the pump capacity increases.
On the other hand, when the loading pressure is reduced when the input side disk 2 is pressed against the power roller 11 with a weak force, the ring 112 is pushed toward the piston 120a side by the biasing force of the spring 116, as shown in FIG. Pump capacity is reduced.
Accordingly, since the variable displacement vane pump 100 can obtain a capacity to cope with the loading pressure from the high pressure side to the low pressure side, the pump loss can be reduced, and the increase in weight and cost can be suppressed.

In this embodiment, the case where the variable displacement vane pump 100 is used as the variable displacement pump has been described as an example, but a variable displacement piston pump may be used as another embodiment.
FIG. 4 is a diagram showing a schematic configuration of a swash plate type variable displacement piston pump 150.
In the variable displacement piston pump 150, a plurality of cylinders 152 are arranged around the piston pump drive shaft 151 at predetermined intervals in the circumferential direction, and the cylinders 152 are held by a cylinder block (not shown).

The piston pump drive shaft 151 is provided with a swash plate 154 called a yoke so as to be rotatable around a fulcrum O, whereby the swash plate 154 can change an inclination angle with respect to the piston pump drive shaft 151. The swash plate 154 rotates around the piston pump drive shaft 151 as the piston pump drive shaft 151 rotates.
The end portion of the piston 153 provided in the cylinder 152 is slidably provided on the swash plate 154, and the piston 153 is rotated by the swash plate 154 around the piston pump drive shaft 151, whereby the end of the piston 153 is provided. The portion slides relatively on the swash plate 154 and reciprocates.
Therefore, when the swash plate 154 rotates as the piston pump drive shaft 151 rotates using the engine as a drive source, the piston 153 reciprocates in the axial direction, and oil is sucked and discharged by this reciprocation.

A cylinder device 160 is provided on the outer peripheral side of the swash plate 154 in parallel with the cylinder 152, and a piston 160 a of the cylinder device 160 is in contact with the swash plate 154.
Further, the swash plate 154 is urged toward the piston 160 a by a spring 161, and the piston 160 a is urged toward the swash plate 154 side by a spring 162.
Therefore, the inclination of the swash plate 154 (inclination angle with respect to the piston pump drive shaft 151) is determined by the relationship between the piston pressure acting on the piston 120a by the loading pressure and the urging force of the spring 161 and the spring 162.
A loading pressure is applied to the cylinder 160b of the cylinder device 160.

In such a variable displacement piston pump 150, the swash plate 154 rotates as the piston pump drive shaft 151 rotates using the engine as a drive source, and thereby the piston 153 reciprocates in the axial direction. Oil is sucked and discharged by this reciprocation.
The oil sucked from an oil pan (not shown) and discharged from the discharge port is supplied to a loading cylinder (not shown) after the hydraulic pressure is adjusted by a loading pressure adjusting valve (not shown).
When the loading pressure of the loading cylinder increases, the piston 160a of the cylinder device 160 moves to the right in FIG. 4 and the swash plate 154 falls (rotates clockwise), so that the reciprocating distance of the piston 160a increases. The pump capacity increases.
On the other hand, when the loading pressure is reduced, the piston 160a moves to the left in FIG. 4 and the swash plate 154 is generated (rotates counterclockwise), so that the reciprocating distance of the piston 160a is reduced and the pump capacity is reduced.

  Accordingly, in the present embodiment, similarly to the first embodiment, the variable displacement piston pump 150 can obtain a capacity for dealing with the loading pressure from the high pressure side to the low pressure side, so that the pump loss can be reduced, Increase in weight and cost can be suppressed.

  The present invention can be applied to a full toroidal continuously variable transmission in addition to a half-toroidal continuously variable transmission. Further, the continuously variable transmission is a combination of a toroidal continuously variable transmission and a planetary gear mechanism. (IVT) can also be applied.

2 Input side disk 3A Output side disk 11 Power roller 80 Press device 100 Variable displacement vane pump (variable displacement pump)
150 Variable displacement piston pump (variable displacement pump)

Claims (2)

An input side disk and an output side disk provided concentrically and rotatably with the respective inner side surfaces facing each other, a power roller sandwiched between these two disks, In a continuously variable transmission having a hydraulic pressing device that presses at least one of them with a desired loading pressure so as to sandwich the power roller,
A continuously variable transmission characterized in that the pump for supplying oil to the pressing device is a variable displacement pump whose capacity can be changed according to the loading pressure.   The continuously variable transmission according to claim 1, wherein the variable displacement pump is a variable displacement vane pump or a variable displacement piston pump.

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