JP2000220702A - Forward / backward switching mechanism for continuously variable transmission - Google Patents

Abstract

(57) [Problem] To prevent the forward clutch from being half-engaged by centrifugal pressure when the engine is idling while the vehicle is stopped, thereby preventing the durability of the clutch plate from deteriorating. SOLUTION: When a forward clutch 23 is engaged to drive-couple between a sun gear 17 and a carrier 21, an input shaft 1
3 and the rotation of the sun gear 17 remain unchanged.
When the reverse gear 22 is engaged and the ring gear 18 is fixed, the rotation of the input shaft 13 and the sun gear 17 is reversed and reaches the input shaft 15 of the continuously variable transmission 14. The clutch drum 23c in which the operating piston 23a of the clutch 23 is included is connected to the carrier 2 as an output element.
Therefore, even when the engine 10 is idling while the vehicle is stopped, the rotation speed of the clutch drum 23c does not increase, and the clutch drum 23c and the working piston 2
3a can be prevented from generating a centrifugal pressure in the working fluid pressure chamber 23e, and the working piston 2
3a can be prevented from bringing the clutch 23 into a semi-engaged state.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a forward / backward switching mechanism for a continuously variable transmission, and more particularly to a forward / backward switching mechanism for preventing the durability of the continuously variable transmission from decreasing when the engine is idling at the preceding stage. Things.

[0002]

2. Description of the Related Art A continuously variable transmission, regardless of whether it is a toroidal type continuously variable transmission or a V-belt type continuously variable transmission, does not have a reverse rotation function, and therefore has a reverse function. When used in a place where forward switching is required, it is necessary to provide a forward / backward switching mechanism at the front or rear stage (usually the front stage) of the transmission body.

The forward / reverse switching mechanism for this purpose generally includes a sun gear, a ring gear, and a carrier rotatably supporting a pinion for transmitting power between these gears.
The above-described input is achieved by fixing a planetary gear set composed of elements as main components, fixing one of these three elements as an input element, another one as an output element, and fixing the other one with a hydraulic brake. The rotation to the input element can be transmitted to the output element by reversing the rotation to the element, and the rotation to the input element can be changed in the rotation direction by connecting two of the three elements to each other by a hydraulically operated clutch. In general, it is configured to be able to transmit to the output element as it is.

[0004] One example is described in, for example, Japanese Patent Application Laid-Open No. 3-204.
As described in Japanese Patent Publication No. 436, a double pinion type planetary gear set is used as a planetary gear set, the sun gear is used as an input element, a carrier is used as an output element, and these input / output elements can be connected with a hydraulic clutch. In some cases, a ring gear, which is the remaining one element, can be fixed by a hydraulically actuated brake. In this forward / reverse switching mechanism, when coupling between the sun gear and the carrier (between the input and output elements) by engaging the hydraulically actuated clutch, the input rotation to the sun gear is transmitted to the carrier in the same rotation direction and the forward rotation is output. When the ring gear is fixed by fastening the hydraulic brake, the ring gear can be used as a reaction force receiver to transmit the input rotation to the sun gear to the carrier in reverse rotation and output the reverse rotation.

[0005]

Conventionally, as described in the above-mentioned literature, it has been customary to construct the above-mentioned hydraulically operated clutch as follows. That is, the clutch drum containing the working piston of the hydraulic clutch is connected to the sun gear which is the input element, the clutch hub is connected to the carrier which is the output element, and the clutch drum and the clutch hub are spline-fitted respectively. The clutch pistons are alternately arranged in the axial direction, and the clutch piston is pressed by the above-mentioned operating piston so that the clutch is engaged.

However, in the conventional configuration in which the clutch drum of the hydraulic clutch is connected to the sun gear, which is an input element, the clutch drum receives the engine rotation via the sun gear, causing the following problems. . That is, when the engine is idled by depressing the accelerator pedal in the neutral state (the vehicle is stopped) in which both the hydraulic clutch and the hydraulic brake are released, the rotational speed of the clutch drum naturally increases, The working fluid remaining in the working fluid pressure chamber defined by the clutch drum and the working piston fitted thereto receives centrifugal force due to rotation to generate a so-called centrifugal pressure.

[0007] This centrifugal pressure pushes the working piston in the clutch drum to bring the hydraulic working clutch into a semi-engaged state while it should otherwise be released, thereby causing the clutch plate to quickly generate heat and slip. Degradation of the hydraulically operated clutch and thus the durability of the forward / reverse switching mechanism. To solve this problem, a centrifugal pressure cancel chamber is set on the side of the working piston far from the working fluid pressure chamber using the method conventionally used in stepped automatic transmissions, and the working fluid is stored here. By doing so, it is conceivable to take measures to cancel the centrifugal pressure. However, this measure inevitably resulted in an increase in the number of parts, which was disadvantageous in terms of cost, and confirmed that it could not be a drastic solution.

A first object of the present invention is to propose a forward / reverse switching mechanism of a continuously variable transmission in which the above-mentioned problem does not occur by devising a mounting location of the clutch drum. .

A second object of the present invention is to propose a forward / reverse switching mechanism of a continuously variable transmission in which the above-mentioned problem is most reliably solved at a place where the clutch drum is mounted. .

According to a third aspect of the present invention, the above-mentioned problem does not occur by devising a mounting location of the clutch drum, and the clutch drum is also used as a brake drum of the hydraulic brake. It is an object of the present invention to propose a forward / reverse switching mechanism of a continuously variable transmission that can be obtained.

According to a fourth aspect of the present invention, there is provided a continuously variable transmission in which the hydraulic clutch can be easily incorporated regardless of whether the clutch drum is mounted in the second or third aspect. It is an object to propose a forward / backward switching mechanism.

According to a fifth aspect of the present invention, there is provided a forward / reverse switching mechanism for a continuously variable transmission, wherein the same operation and effects as those of the first to fourth aspects can be achieved using an inexpensive planetary gear set. The purpose is to propose.

[0013]

SUMMARY OF THE INVENTION For these purposes, first, a forward / reverse switching mechanism of a continuously variable transmission according to the first invention is provided.
A planetary gear set consisting of a sun gear, a ring gear, and a carrier rotatably supporting a pinion for transmitting power between these gears. One of these three elements is used as an input element, and another The element is an output element, and rotation of the input element can be reversed to be transmitted to the output element by fixing the remaining one element with a hydraulic brake.
A forward-reverse switching mechanism of a continuously variable transmission capable of transmitting rotation to the input element to the output element without changing the rotation direction by coupling two of the three elements to each other with a hydraulically operated clutch. A clutch drum including an operating piston of the hydraulic clutch is formed integrally with one of two elements other than the input element.

A forward-reverse switching mechanism for a continuously variable transmission according to a second invention is characterized in that in the first invention, the clutch drum is formed integrally with the output element.

According to a third aspect of the present invention, there is provided a forward / reverse switching mechanism for a continuously variable transmission according to the first aspect, wherein the clutch drum is formed integrally with the remaining one element, and is also used as a brake drum for the hydraulic brake. It is characterized by having done.

According to a fourth aspect of the present invention, there is provided a continuously variable transmission mechanism for a continuously variable transmission according to any one of the first to third aspects, wherein the planetary gear set is a double pinion type planetary gear set, a sun gear is an input element, and a carrier. And the clutch hub of the hydraulic clutch is connected to a sun gear.

According to a fifth aspect of the present invention, there is provided a continuously variable transmission mechanism for a continuously variable transmission according to any one of the first to third aspects, wherein the planetary gear set is a single pinion type planetary gear set, a sun gear is an input element, and a ring gear. Is the output element,
The clutch hub of the hydraulic clutch is connected to a sun gear.

[0018]

The forward / reverse switching mechanism has a sun gear, a ring gear, and a carrier, which constitute a planetary gear set, in which rotation is input to one of the three input elements and another one of the three elements is an output element. At this time, the rotation of the input element is reversed and transmitted to the output element by fixing the remaining one element with a hydraulically actuated brake, and two of the three elements are mutually output. By coupling with a hydraulic clutch, the rotation to the input element is transmitted to the output element without changing the rotation direction and output from this

According to the first aspect of the invention, the clutch drum containing the operating piston of the hydraulic clutch is formed integrally with one of the two elements other than the input element. The rotation is not input, and even when the engine is idled by depressing the accelerator pedal in the neutral state (the vehicle is stopped) in which both the hydraulic clutch and the hydraulic brake are released, The rotation speed of the drum does not increase.

Therefore, at this time, a situation in which the working fluid remaining in the working fluid pressure chamber defined by the clutch drum and the working piston fitted thereto receives centrifugal force due to rotation to generate centrifugal pressure. Can be avoided.
Conventionally, the working piston in the clutch drum is pushed by this centrifugal pressure, and the hydraulic clutch is put in a half-engaged state while it should be released, and the clutch plate deteriorates early due to heat generation and slip. In the first aspect, the problem that the durability of the forward / reverse switching mechanism is remarkably reduced is avoided.

In the second aspect of the invention, since the clutch drum is formed integrally with the output element, the following effects can be obtained. In other words, since the output element keeps the rotation speed at 0 in the neutral state (the vehicle is stopped), the rotation speed of the clutch drum is also set to 0, and the centrifugal pressure is completely reduced. Can be eliminated,
The above-mentioned problem can be solved most reliably.

In the third aspect of the present invention, the clutch drum is formed integrally with the remaining one element, and is used also as the brake drum of the hydraulic brake, so that the following operation and effect can be obtained. In other words, the remaining one element is not guaranteed to keep the rotation speed at 0 in the above neutral state (vehicle stopped state), but at least the engine rotation is not input. Even when the engine is idling in step (1), the rotational speed of the clutch drum is not increased, and the problem of durability due to the centrifugal pressure can be avoided. In addition, since the remaining one element is to be fixed by the hydraulic operation brake during reverse rotation transmission, the clutch drum integrally formed with the remaining one element is used as a brake drum of the hydraulic operation brake. Since the number of large parts can be reduced, the forward / backward switching mechanism can be reduced in cost and the assembling workability can be improved.

In the fourth invention, the planetary gear set is a double pinion type planetary gear set, the sun gear is an input element, the carrier is an output element, and the clutch hub of the hydraulic clutch is connected to the sun gear. Regardless of whether the drum is mounted in the second or third invention, the clutch drum and the clutch hub are easily arranged radially opposite to each other, so that the hydraulic clutch can be easily assembled. be able to.

In the fifth invention, the planetary gear set is a single pinion type planetary gear set, the sun gear is an input element, the ring gear is an output element, and the clutch hub of the hydraulic clutch is connected to the sun gear. Using the single pinion type planetary gear set, the same functions and effects as the first to fourth inventions can be achieved.

[0025]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 diagrammatically shows a V-belt type continuously variable transmission provided with a forward / reverse switching mechanism according to one embodiment of the present invention, in which 10 is an engine. An input shaft 13 of a forward / reverse switching mechanism 12 is connected to a crankshaft 10 a of the engine 10 via a torque converter 11.
And the forward / reverse switching mechanism 12 is connected to the input shaft 1
3 is transmitted to the input shaft 15 of the V-belt type continuously variable transmission 14 in a reversible manner.

The forward / reverse switching mechanism 12 is a double pinion type planetary gear set. The double pinion type planetary gear set includes a sun gear 17, a ring gear 18, an inner pinion 19 meshing with the sun gear 17, and an outer pinion meshing with the ring gear 18. And an inner pinion 19 and a carrier 21 that rotatably support the inner pinion 19 and the outer pinion 20 in a mutually meshed state. Sun gear 1
7 is connected to the input shaft 13 to serve as an input element.
Is connected to the input shaft 15 of the continuously variable transmission 14 and used as an output element.

The forward / reverse switching mechanism 12 further includes a hydraulically operated reverse brake 22 and a hydraulically operated forward clutch 23. The reverse brake 22 enables the ring gear 18 to be fixed to the transmission case by hydraulically operating a piston 22a. ,
The forward clutch 23 enables the sun gear 17 and the carrier 21 to be connected to each other by the hydraulic operation of the piston 23a.

The V-belt type continuously variable transmission 14 includes a primary pulley 24 that rotates together with the input shaft 15 thereof, and an output shaft 2.
The main components are a secondary pulley 26 that rotates together with the pulley 5, and a V-belt 27 stretched between these pulleys. The movable flange 24a of the primary pulley 24 and the movable flange 26a of the secondary pulley 26 are respectively urged toward the corresponding fixed flanges by the hydraulic pressure supplied into the chambers 24b, 26b, so that the V-belt 27 is fixed to the movable flange. Pressure is applied between the flanges so that the V-belt 27 can transmit power between the primary pulley 24 and the secondary pulley 26.

By controlling the hydraulic pressure difference between the chambers 24b and 26b, the movable flange 24a of the primary pulley 24 approaches the fixed flange, and the movable flange 26a of the secondary pulley 26 is separated from the fixed flange. Movable flange 2 of pulley 24
4a is separated from the fixed flange and the movable flange 26a of the secondary pulley 26 is moved closer to the fixed flange, so that the continuously variable transmission 14 moves from the low speed gear ratio to the high gear speed ratio or vice versa. The speed can be changed steplessly toward the low speed side gear ratio.

An output gear 28 is fixed to the output shaft 25, and a gear 29 meshing with the output gear 28 is provided on a counter shaft 30, and the final drive gear set 32 drives and connects the counter shaft 30 and the differential gear device 31. I do. Output shafts 33 and 34 projecting from both sides of the differential gear device 31 are drivingly connected to left and right drive wheels (not shown).

The operation of the vehicle power train will now be described. The engine rotation transmitted from the engine crankshaft 10a to the input shaft 13 via the torque converter 11 is input to the sun gear 17 of the planetary gear set 16 to rotate it. In the neutral state where both the forward clutch 23 and the reverse brake 22 are released, the input shaft 13 and the sun gear 1
Since the rotation of 7 does not reach the input shaft 15 of the V-belt type continuously variable transmission 14 and power is not transmitted to the drive wheels, the vehicle can be stopped.

Here, the forward clutch 23 is connected to the piston 23
When the sun gear 17 and the carrier 21 are driven and coupled by the hydraulic operation of a, the rotation of the input shaft 13 and the sun gear 17 reaches the input shaft 15 of the V-belt continuously variable transmission 14 as it is. The power is transmitted to the drive wheels via the output gear 28, the countershaft 30, the final drive gear set 32, and the differential gear device 31 during the continuously variable transmission by the belt-type continuously variable transmission 14, so that the vehicle travels forward. Can be.

When the vehicle travels backward, the ring gear 18 is fixed by engaging the reverse brake 22 by hydraulic operation of the piston 22b. At this time, the rotation of the input shaft 13 and the sun gear 17 is reversed to reach the input shaft 15 of the V-belt continuously variable transmission 14 using the ring gear 18 as a reaction force element, and thereafter, the V-belt continuously variable transmission 14 and the output gear 2
8, reverse power is transmitted to the drive wheels via the countershaft 30, the final drive gear set 32, and the differential gear device 31, so that the vehicle can travel backward.

Here, a specific configuration example of the forward / reverse switching mechanism 12 will be described with reference to FIG. 2. The input shaft 13 is rotatably supported in a hollow fixed shaft 42.
Is a pump cover 43 integrally connected to the transmission case 41.
In the boss portion 43a. The transmission input shaft 15 integrated with the primary pulley 24 is fitted to the inner end of the input shaft 13 in a coaxial butt relationship, and the transmission case 4 is
1 to be rotatably supported.

The sun gear 17 of the planetary gear set 16 is connected to the input shaft 1
3 and the clutch hub 23b of the forward clutch 23 is integrally connected to the sun gear 17. On the other hand, the clutch drum 23c, to which the operating piston 23a of the forward clutch 23 is fitted, is rotatably supported on the boss 43a at the inner peripheral portion thereof.
3c is radially opposed to the clutch hub 23b, and the planetary gear set 16
Of the V-belt type continuously variable transmission. Outer peripheral portion of clutch drum 23c and clutch hub 23
b, a clutch pack in which the clutch plates 23d spline-fitted to these are alternately arranged.

The brake drum 22b of the reverse brake 22 is connected to the ring gear 18 of the planetary gear set 16, and the brake drum 22b extends around the outer circumference of the clutch drum 23c. Then, between the extending portion of the brake drum 22b and the transmission case 41, a brake pack in which the brake plates 22c spline-fitted thereto are alternately arranged is interposed. Working piston 22 of reverse brake 22
a is slidably fitted in the transmission case 41 so as to face the brake pack in the axial direction.

The forward / reverse switching mechanism 12 having the above-described specific structure connects the clutch drum 23c including the operating piston 23a of the forward clutch 23 to the carrier 21 as the output element instead of the sun gear 17 as the input element. Due to the wearing, the following effects can be obtained. That is, since the clutch drum 23c is connected to the carrier 21, which is an output element, the clutch drum 23c does not always receive the engine rotation, and the forward clutch 23 and the reverse brake 22 are both released. Even when the engine 10 (see FIG. 1) is idly blown by depressing the accelerator pedal while the vehicle is stopped), the rotation speed of the clutch drum 23c does not increase.

Therefore, at this time, the working fluid remaining in the working fluid pressure chamber 23e defined by the clutch drum 23c and the working piston 23a fitted thereto does not receive centrifugal force due to rotation, and the chamber 23e It is possible to avoid the occurrence of a situation in which a centrifugal pressure is generated inside. Therefore, there is no adverse effect such that the working piston 23a in the clutch drum 23c is pushed by the centrifugal pressure to bring the forward clutch 23 into a half-engaged state, and the clutch plate 23d is deteriorated early due to heat generation and slip. It is possible to prevent a problem that the durability of the forward / reverse switching mechanism is significantly reduced.

Particularly, as in the present embodiment, when the clutch drum 23c is connected to the carrier 21 as an output element, the number of revolutions is maintained at 0 when the carrier 21 is in a neutral state (the vehicle is stopped). Therefore, the rotational speed of the clutch drum 23c is also set to 0, and the centrifugal pressure can be completely prevented from being generated, and the above-mentioned problem can be solved most reliably. This effect is not limited to the case where the forward / reverse switching mechanism 12 is arranged at the preceding stage of the V-belt type continuously variable transmission. The same applies to the case where the continuously variable transmission is not a V-belt type continuously variable transmission but another type of continuously variable transmission such as a toroidal type continuously variable transmission.

Also, instead of connecting the clutch drum 23c to the carrier 21 as an output element, the clutch drum 23c is connected to the ring gear 18 as shown in FIG. 3, and the forward clutch 23 connects the sun gear 17 and the ring gear 18 to move forward. Even when the rotation is transmitted, the ring gear 18 and the clutch drum 23c
However, there is no guarantee that the number of revolutions will be kept at 0 in the neutral state (vehicle stopped state), but at least the engine rotation is not input, so the neutral state (vehicle stopped state)
When the engine is idling, the rotation speed of the clutch drum 23c is not increased, and the problem of durability due to the centrifugal pressure can be avoided. Moreover, in this case, since the ring gear 18 is to be fixed by the reverse brake 22 during reverse rotation transmission, the ring gear 18
Can be used also as the brake drum of the reverse brake 22, and the reduction of the number of large parts can reduce the cost of the forward / reverse switching mechanism and also improve the assembly workability.

In the present embodiment, the planetary gear set 16 is a double pinion type planetary gear set, and the sun gear 1
7 is an input element, the carrier 21 is an output element, and the clutch hub 23b of the forward clutch 23 is connected to the sun gear 17, so that the connecting parts of the clutch drum 23c are the carrier 21 as shown in FIGS. Even when the ring gear 18 is used as shown in FIG. 3, the clutch drum 23c and the clutch hub 23b can be easily arranged to face each other in the radial direction, so that the forward clutch 23 can be easily assembled.

Instead of using the planetary gear set 16 as a double pinion type planetary gear set, a single pinion type planetary gear set in which the pinion 45 meshes with both the sun gear 17 and the ring gear 18 as shown in FIGS. However, the idea of the present invention described above is applicable. In the embodiment shown in FIG. 4, the sun gear 17 is connected to the shaft 13 as an input element, the ring gear 18 is connected to the shaft 15 as an output element, and the carrier 21 is a reaction force to be appropriately fixed by the reverse brake 22. Element. The clutch hub 23b of the forward clutch 23 is connected to the sun gear 17, and the forward clutch 23
Drum 23 fitted with a working piston 23a
The forward clutch 23 is connected to the carrier 21 so that the forward clutch 23 can connect the sun gear 17 and the carrier 21 to achieve the forward rotation transmission state.

In this case as well, there is no guarantee that the number of revolutions is maintained at 0 when the clutch drum 23c is in the neutral state (the vehicle is stopped), but at least the engine speed is not input. When the engine is idling in the stopped state, the rotational speed of the clutch drum 23c is not increased, and the problem of durability due to the centrifugal pressure can be avoided. Moreover, in this case, carrier 2
1 is to be fixed by the reverse brake 22 at the time of reverse rotation transmission, the clutch drum 23c connected to the carrier 21 can be used also as the brake drum of the reverse brake 22, and the forward / backward movement due to the decrease in the number of large parts is reduced. It is possible to realize not only a reduction in the cost of the switching mechanism but also an improvement in assembly workability.

In the embodiment shown in FIG. 5, the sun gear 17 is connected to the shaft 13 as an input element in the same manner as in FIG.
The ring gear 18 is connected to the shaft 15 to be an output element, the carrier 21 is a reaction force element to be appropriately fixed by the reverse brake 22, and the clutch hub 23 b of the forward clutch 23 is connected to the sun gear 17. The clutch drum 23c, to which the working piston 23a is fitted, is connected to the ring gear 18 as an output element.
Are connected between the sun gear 17 and the ring gear 18 so that a forward rotation transmission state can be achieved.

In this case, the number of revolutions is maintained at 0 when the clutch drum 23c is in the neutral state (vehicle stopped state), so that even when the engine is idling in the neutral state (vehicle stopped state), the clutch drum 23c is stopped. Does not rotate at all, and the problem of durability due to the centrifugal pressure can be reliably avoided.

In both FIGS. 4 and 5,
Connect the clutch hub 23b of the forward clutch 23 to the sun gear 17
Therefore, regardless of whether the binding part of the clutch drum 23c is the carrier 21 as shown in FIG. 4 or the ring gear 18 as shown in FIG.
3c and the clutch hub 23b can be easily arranged to face each other in the radial direction, so that the incorporation of the forward clutch 23 can be facilitated. In any of the embodiments shown in FIG. 4 and FIG. 5, since an inexpensive single pinion type planetary gear set is used as the planetary gear set 16, the same operation and effect as described above can be achieved at low cost. be able to.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating a V-belt type continuously variable transmission including a forward / reverse switching mechanism according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a main part illustrating a specific configuration of a forward / reverse switching mechanism in the embodiment of FIG. 1;

FIG. 3 is a schematic diagram showing a forward / reverse switching mechanism according to another embodiment of the present invention.

FIG. 4 is a schematic diagram showing a forward / reverse switching mechanism according to still another embodiment of the present invention.

FIG. 5 is a schematic diagram showing a forward / reverse switching mechanism according to still another embodiment of the present invention.

[Explanation of symbols]

 10 Engine 11 Torque converter 12 Forward / reverse switching mechanism 14 V-belt type continuously variable transmission 16 Planetary gear set 17 Sun gear 18 Ring gear 19 Inner pinion 20 Outer pinion 21 Carrier 22 Reverse brake (hydraulic brake) 22a Working piston 22b Brake drum 23 Forward clutch (hydraulic pressure operated clutch) 23a Working piston 23b Clutch hub 23c Clutch drum 23d Clutch plate 24 Primary pulley 25 Output shaft 26 Secondary pulley 27 V belt 30 Counter shaft 31 Differential gear device 32 Final drive gear set 41 Transmission case 42 Hollow Fixed shaft 43 Pump cover 45 Pinion

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hideaki Nakayama 2-12 Kawanamicho, Atsuta-ku, Nagoya-shi, Aichi Inside Aichi Machine Industry Co., Ltd. (72) Inventor Takanori Kanehisa 2 Takaracho, Kanagawa-ku, Yokohama-shi, Kanagawa Nissan F-term (reference) in Automobile Co., Ltd. 3D039 AA00 AC03 AC24 AC34 AD23 3J028 EA08 EA09 EA28 EB10 EB16 EB35 EB37 EB44 EB50 EB62 FB06 FB14 FC13 FC23 FC64 FD25 GA01 3J050 AB03 AB07 AB10 BA03 BA18 BB15

Claims (5)

[Claims] 1. A planetary gear set comprising a sun gear, a ring gear, and a carrier rotatably supporting a pinion for transmitting power between these gears, wherein one of these three elements is an input element. By rotating another one element as an output element and fixing the remaining one element with a hydraulically actuated brake, the rotation to the input element can be reversed and transmitted to the output element. A forward-reverse switching mechanism of a continuously variable transmission capable of transmitting the rotation to the input element to the output element without changing the rotation direction by coupling the elements to each other with a hydraulically operated clutch; A forward / reverse switching mechanism for a continuously variable transmission, wherein a clutch drum containing a piston is integrally formed with one of two elements other than the input element. 2. The forward / reverse switching mechanism of a continuously variable transmission according to claim 1, wherein the clutch drum is formed integrally with the output element. 3. The continuously variable transmission according to claim 1, wherein the clutch drum is formed integrally with the remaining one element and is also used as a brake drum of the hydraulic brake. Switching mechanism. 4. The hydraulic pressure operated clutch according to claim 1, wherein the planetary gear set is a double pinion type planetary gear set, a sun gear is an input element, a carrier is an output element, and Forward / backward switching mechanism for a continuously variable transmission, which is connected to a sun gear. 5. The planetary gear set according to claim 1, wherein the planetary gear set is a single pinion type planetary gear set, the sun gear is an input element, and the ring gear is an output element.
A forward-reverse switching mechanism for a continuously variable transmission, wherein a clutch hub of the hydraulic clutch is connected to a sun gear.