JPH03140657A - Continuously variable transmission - Google Patents

Abstract

PURPOSE:To make a bandbrake mechanism effectively adoptable without incurring any dimensional enlargement by installing a brake drum of a band brake mechanism rotatably in a sun gear of a planetary gear mechanism as one body, and setting up its braking surface in a position surrounding the circumference of a ring gear. CONSTITUTION:A band brake mechanism 25 installs its bottom part 25a1 tight to a supporting shaft 1a of a sun gear 1 and arranges its drum braking surface 25a2 in the form surrounding the circumference of a ring gear 3. At time of low speed forward movement, clutches 11, 13 are ON and a clutch 12 is OFF, while a part of engine power is transmitted to an output shaft 10 through a mechanical transmission system (a) at the low speed side and the rest through a hydraulic transmission system A, respectively. At time of running at high speed, the clutches 12, 13 are ON, the clutch 11 is OFF, and a part of the engine power is transmitted to the output shaft 10 as well through a mechanical transmission system (b) at the high speed side and the rest through a hydraulic transmission system B, respectively. At time of drawing-in of a top lockup mode, the transmission system B is locked by the brake mechanism 25 and thereby its high efficiency is attainable, thus a pure hydraulic drive little in loss can be realized likewise even at time of backward movement.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a continuously variable transmission device that can be widely used in various industrial fields such as industrial machinery and vehicles.

[Prior Art] A so-called hydraulic transmission (HST) is known as a continuously variable transmission using a fluid pump/motor. However, although this device has excellent continuously variable speed, it is not necessarily efficient and the speed range is not satisfactory. Therefore, the H8T and a planetary gear mechanism are used together to improve power transmission. A hydromechanical continuously variable transmission (HMT) has been developed that allows both the continuously variable speed characteristics of the H8T and the high efficiency of gear transmission to be exhibited by dividing the H8T and the planetary gear mechanism. ing.

(References, Hydraulic Engineering (Tomoo Ishihara, Asakura Shobo), Theory and Practice of Piston Pump Motors (Sadao Ishihara, Corona Publishing)).

FIG. 4 shows a continuously variable transmission device shown in Japanese Patent Application No. 1983-335655, which is composed of a sun gear 1, a planetary gear 2, and a ring gear 3, and a planetary gear mechanism 5 in which a human power shaft 4 is connected to the planetary gear 2, and this planetary gear mechanism. 5 as the main component, a low-speed mechanical transmission system a formed in the direction from the planetary gear 2 to the sun gear 1, and a high-speed mechanical transmission system formed in the direction from the planetary gear 2 to the ring gear 3, these machines For the type transmission systems a and b, one fluid pump/motor 7 is located near the low-speed transmission end a (,
By connecting the input/output shaft 7a of the other fluid pump/motor 8 to the vicinity of the high-speed transmission end b0, a variable speed fluid transmission is established in parallel to the mechanical transmission systems a and b. A fluid transmission mechanism 9 forming systems A and B, and the low speed transmission end a. A low-speed side clutch 11 connects and disconnects the high-speed side transmission end b0 to the output shaft 10, and a high-speed side clutch 12 connects and disconnects the high-speed side transmission end b0 to the output shaft 10.

Reference numeral 13 denotes a forward clutch, which normally connects the sun gear 1 to the low-speed transmission end a(,), and disconnects the sun gear 1 from the low-speed transmission end a□ only when reversing.

However, if the engine power is input from the human power shaft 4 of the continuously variable transmission configured in this way and the wheels are not driven by the output shaft 10, low speed is achieved by switching both clutches 11 and 12 contradictoryly. You will be able to select either mode or fast mode. In other words, when moving forward at low speed, clutches 11 and 13 are "on" and clutch 12 is "off", so that the engine power is divided in parallel at the time of input, and a portion is sent to the output shaft through the mechanical transmission system a on the low speed side. 10, and the rest is transmitted to the output shaft 10 through the fluid transmission system A.
When driving at high speeds, the transmission is transmitted to clutch 12.
13 is "on" and the clutch 11 is "disconnected", a part of the engine power is transmitted to the output shaft 10 through the high-speed mechanical transmission system, and the rest is transmitted to the hydraulic transmission system B.
It will be transmitted to the output shaft 10 through. On this occasion,
If the device shown in the figure is set to top lock-up mode (a mode in which the vehicle travels while maintaining the speed ratio represented by the output rotation speed/input rotation speed at its maximum value), braking is applied directly or indirectly to sun gear 1. The brake mechanism 14 locks the hydraulic transmission system B during high-speed running, allowing power to be transmitted only through the mechanical transmission system on the high-speed side, allowing pure mechanical drive. This ensures high efficiency.

Also, when reversing at low speed, clutch 11 is "engaged" and clutch 1 is "engaged".
2.13 becomes "disconnected", all the engine power will be transmitted to the output shaft 10 only through the fluid transmission system A, but at this time, power circulation etc. will occur and appropriate output will not be obtained. In order to prevent this from happening, the brake mechanism 14 is activated to lock the sun gear 1, thereby enabling pure hydraulic drive with less loss.

[Problems to be solved by the invention] In this way, when applying a continuously variable transmission to a vehicle,
Applying braking directly or indirectly to the sun gear 1 has an important meaning, and the conventional brake mechanism 14 for this purpose includes a wind turbine 14a that is rotatable integrally with the sun gear 1 as shown in the figure. 14a is configured such that a claw 14c attached to a fixing member 14b can be engaged and disengaged by an actuator 14d. However, this engagement/disengagement operation cannot be performed successfully unless the pawl 14a rotates slowly relative to the pawl 14c and is performed promptly, so it is difficult in terms of mechanism, operation, and control. A similar problem exists in a wet type multi-disc clutch. Therefore, in recent years, it has been considered as an effective means to adopt a band brake mechanism instead of such a system. However, in order to generate the necessary brake torque using this type of brake mechanism, the drum diameter must be increased, and if it is simply placed around the sun gear, the external dimensions of the brake drum can be used as installation space. Then,
This inevitably leads to an increase in the size of the device.

The present invention was made based on this viewpoint, and by realizing a brake mechanism that has a simplified mechanism, operation, control, and installation space, it is possible to enter a lock-up mode, circulate power, etc. It is an object of the present invention to provide a continuously variable transmission device that can effectively prevent the above problems with a compact configuration.

[Means for Solving the Problems] In order to achieve the above object, the present invention employs the following configuration.

That is, the continuously variable transmission device according to the present invention includes a sun gear,
A planetary gear mechanism consisting of a planetary gear and a ring gear with an input shaft connected to the planetary gear, a low-speed mechanical transmission system formed mainly from the planetary gear in the direction from the planetary gear to the sun gear, and a low-speed mechanical transmission system formed in the direction from the planetary gear to the ring gear. The input/output shaft of one fluid pump/motor is connected near the low-speed side transmission end to these mechanical transmission systems, and the other fluid is connected near the high-speed side transmission end. A fluid transmission mechanism that forms a variable speed fluid transmission system in parallel to the mechanical transmission system by connecting the input and output shafts of a pump/motor, and a low speed transmission mechanism that connects and disconnects the low speed transmission end from the output shaft. and a high-speed side clutch that connects and disconnects the high-speed side transmission end with respect to the output shaft, so that either the low-speed mode or the high-speed mode can be selected by switching both clutches contrary to each other. In this configuration, a brake drum of a band brake mechanism is rotatably provided on the sun gear of the planetary gear mechanism, and a braking surface of the brake drum is disposed at a position surrounding the outer periphery of the ring gear.

In addition, in order to realize a simpler structure, the low-speed mechanical transmission system is formed in the direction from the planetary gear to the ring gear, and the high-speed mechanical transmission system is formed in the direction from the planetary gear to the sun gear. It is preferable to set the brake drum braking surface of the band brake mechanism around the outer periphery of the ring gear of the planetary gear mechanism.

[Function] When a brake drum is provided so as to be able to rotate integrally with the sun gear, and the braking surface of the brake drum is placed in a position surrounding the outer periphery of the ring gear, the entire planetary gear mechanism is housed in the hollow of the brake drum, and the brake drum From the perspective of introducing this, a large drum diameter can be secured without requiring a separate installation space. Also,
If the sun gear and ring gear are configured to play roles opposite to those described above, it is possible to enter the top lock-up mode and prevent power circulation through the ring gear, and the outer periphery of the ring gear itself can be used as a braking surface for the brake drum. By using the band brake, there is no need to provide a separate brake drum, and as a result, it is possible to further simplify the band brake mechanism.

[Example] Hereinafter, an example of the present invention will be described with reference to FIGS. 1 and 2. Note that in FIG. 1, parts common to those in FIG. 4 are given the same reference numerals.

As schematically shown in FIG. 1, the continuously variable transmission according to the present invention has a sun gear 1 meshing with the inside of planetary gears 2 provided at equal intervals in the circumferential direction, and a ring gear 3 meshing with the outside. A planetary gear mechanism 5 is constructed, and an input shaft 4 connected to an engine is connected to the center of a gear retainer 14 that supports a planetary gear 2. This planetary gear mechanism 5 is the main body, and around it is a low-speed mechanical transmission system a consisting of planetary gear 2 → sun gear 1 → gear 15 → gear 16 → clutch 13 → gear 17 → gear 18 → transmission end a0. , planetary gear 2 → ring gear 3 → transmission end. The high-speed side mechanical transmission system consists of: The clutch 13 is connected when moving forward and disconnected when moving backward.

Further, a fluid transmission mechanism 9 is provided in which a pair of variable displacement fluid pump/motor 7.8 are connected in series via a hydraulic circuit 19 similar to that of a normal H3T. The input/output shaft 7a is connected to the low speed transmission end a□ via the gears 17 and 18, and the fluid pump/
By connecting the input/output shaft of the motor 8 to the high speed transmission end bo via the 8a gear 20 and gear 21, variable speed fluid transmission systems A and B are formed (the fluid pump/motor 8 (The fluid pump/motor 7 functions as a motor at low speed and a pump at high speed.) The output shaft 10 connected to the wheels is connected to a common rotating element 24 via gears 22 and 23, and a low-speed clutch connects and disconnects the low-speed transmission end a0 to this rotating element 24. 11 and a high-speed side clutch 12 that connects and disconnects the high-speed side transmission end b0.

Braking can be applied to the sun gear 1 of the planetary gear mechanism 5 through a band brake mechanism 25. As shown in FIGS. 1 and 2, this band brake mechanism 25 has a bottom portion 25a1 fixed to the support shaft 1a of the sun gear 1, and a cylindrical portion (brake drum braking surface).
A cylindrical brake drum 25a with a bottom is disposed around the outer periphery of the ring gear 3, a band 25b is provided around the brake drum braking surface 25a2 of the brake drum 25a so as to be able to approach and separate from the brake drum braking surface 25a2, and band 25b
and an actuator 25C for tightening as appropriate. It is effective to have the actuator 25C and other actuators controlled by a microcomputer.

However, in a vehicle equipped with a continuously variable transmission configured in this way, when moving forward at low speed, the clutches 11 and 13 are "engaged" and
By disengaging the clutch 12, the engine power is divided in parallel at the time of input, and the negative part is the mechanical transmission system a on the low speed side.
The remaining power is transmitted to the output shaft 10 through the fluid transmission system A, and when driving at high speed, the clutches 12 and 13 are "on" and the clutch 11 is "disconnected". As a result, part of the engine power is transmitted to the output shaft 10 through the mechanical transmission system on the high-speed side, and the rest is transmitted to the output shaft 10 through the hydraulic transmission system B. When entering the plotter up mode, the band brake mechanism 25 is activated to apply braking to the sun gear 1, thereby locking the hydraulic transmission system B, allowing power to be transmitted only through the mechanical transmission system on the high-speed side, resulting in pure mechanical drive. In addition, when reversing, the clutch 11 is "engaged" and the clutches 12.13 are "disengaged", so that all the engine power is transmitted only through the hydrodynamic transmission system A to the output shaft 10. At this time, the band brake mechanism 2
5 to apply braking to and lock the sun gear 1, it is possible to effectively prevent power circulation and realize pure hydraulic drive with less loss.

The band brake mechanism employed in the illustrated device simply has a brake drum 25a fixedly attached to the sun gear 1, and its brake drum braking surface 25a2 is placed at a position surrounding the outer periphery of the ring gear 3. The entire planetary gear mechanism 5 is housed within the hollow space of the brake drum 25a.

Therefore, from the viewpoint of introducing the drum 25a, it is possible to secure a large drum diameter without requiring a separate mounting space. On the other hand, if, for example, a brake drum made as a separate item is simply fixed to the support shaft 1a of the sun gear 1, the support shaft 1a must be made long and the drum and the planetary gear mechanism must be arranged in an overlapping manner. Instead, it becomes inevitable that they will be turned into dolls. Therefore, the advantage of using the illustrated device is great. Also, compared to conventional pawl clutches, this clutch has a band 25b attached to the brake drum 25a even if the actuator 25c is operated relatively casually.
is securely tightened and the desired locking effect is obtained.
The number of parts is small, the mechanism is simple, and the operation and timing can be controlled much more easily.

Incidentally, in order to further pursue compactness, the configuration shown in FIG. 3 is also effective. This device reverses the roles played by the sun gear 1 and the ring gear 3 in the previous embodiment, and allows the ring gear 3 to be used to draw in the trap plotter and prevent power circulation.

Specifically, in the above embodiment, the planetary rotation speed of the planetary gear mechanism 5 is Spl, the ring rotation speed is Sr, the sun rotation speed is 88%, the number of ring gear teeth/the number of sun gear teeth = 1, /ρ
In this case, there is a relationship such as 5p=Sr/ (1+ρ) +pSs/ (1+ρ), and the rotation speed of the input shaft 4 is
), the rotational speed of the input/output shaft 8a is SR, the rotational speed of the input/output shaft 7a is SS, and the reduction ratio of these is PL=Sr/
When 5RSF2=Ss/SS, 5E=SR/(
1 + ρ) PL + ρSS / (1 + ρ) F2...■ On the other hand, in the one shown in Fig. 3, one fluid pump/motor 7 and the other fluid pump/motor 8 are connected as follows. Ideally, the arrangement is opposite to the above, and the reduction ratio F
1. If the reduction ratio of the part corresponding to F2 is fl, F2, then 5E=SS/(1+ρ) f2+ρSR/(1+ρ) f
The relationship becomes l...■. Therefore, fl=[”LXρ, f'2=
If you choose F2/ρ, the formula is SE=ρSS/(1+ρ) r'2+sR/(1+ρ)
Fl, which has the same form as the formula ■. That is, if the gear ratio is selected appropriately, the mechanical transmission system in the direction from planetary gear 2 to ring gear 3 is set to the low speed side, and planetary gear 2
The mechanical transmission system in the direction from
can function as a motor at low speeds and as a pump at high speeds, and the fluid pump/motor 8 can function as a pump at low speeds and a motor at high speeds). In this way, when a band brake is added for the same purpose as in the embodiment described above, the outer periphery of the ring gear 3 can be used as the braking surface of the brake drum. The continuously variable transmission shown in FIG.
This is a simple structure that includes a band 26b that is provided around the ring gear so as to be able to move toward and away from the outer periphery of the ring gear, and an actuator (not shown) that tightens the band 26b appropriately. For this reason, it is possible to achieve the compactness of the -layer while having the same effects as those of the above-mentioned embodiments.

Although the embodiments of the present invention have been described above, the brake drum may be attached in any manner as long as it can rotate integrally with the sun gear. Furthermore, when locking the ring gear, the reduction ratio can also be adjusted using other gears. In addition, the configuration of each part is not limited to the illustrated example, and various modifications can be made without departing from the spirit of the present invention.

[Effects of the Invention] The present invention can effectively employ a band brake mechanism without increasing the structural size through the above-described configuration. Therefore, it is possible to provide a continuously variable transmission device that can easily mechanically and controllably prevent the power from being drawn into the engine and the power from being circulated.

[Brief explanation of the drawing]

1 and 2 show one embodiment of the present invention, with FIG. 1 being a schematic circuit diagram and FIG. 2 being a sectional view of a main part. FIG. 3 is a sectional view corresponding to FIG. 2 showing another embodiment. Fourth
The figure is a circuit diagram corresponding to FIG. 1 showing a conventional example. a... Low speed side mechanical transmission system ao... Low speed side transmission end b... High speed side mechanical transmission system bo... High speed side transmission end A, B... Variable speed fluid type transmission System 1...Sun gear 2...Planetary gear 3
...Ring gear 4...Input shaft 5...Planetary gear mechanism 7...One fluid pump/motor 7a...Input/output shaft 8...Other fluid pump/motor 8a...Input/output Shaft 9...Fluid transmission mechanism 10
...Output shaft 11...Low speed side clutch 1
2...High-speed side clutch 25.26...Band brake mechanism 25a...Brake drum 25a2. 26a...Brake drum braking surface

Claims (2)

[Claims] (1) A planetary gear mechanism consisting of a sun gear, a planetary gear, and a ring gear, with an input shaft connected to the planetary gear,
A low-speed mechanical transmission system formed in the direction from the planetary gear to the sun gear, a high-speed mechanical transmission system formed in the direction from the planetary gear to the ring gear, and these mechanical transmission systems, with this planetary gear mechanism as the main body. The mechanical transmission system is constructed by connecting the input/output shaft of one fluid pump/motor near the low-speed transmission end and the input/output shaft of the other fluid pump/motor near the high-speed transmission end. a fluid transmission mechanism that forms a variable speed fluid transmission system in parallel with the above, a low speed clutch that connects and disconnects the low speed transmission end to the output shaft, and a low speed clutch that connects and disconnects the high speed transmission end to the output shaft. and a high-speed side clutch, and is configured such that either the low-speed mode or the high-speed mode can be selected by switching both clutches in a reverse manner, wherein the sun gear of the planetary gear mechanism is provided with a band brake mechanism. A continuously variable transmission characterized in that a brake drum is integrally rotatable, and the braking surface of the brake drum is arranged to surround the outer periphery of a ring gear. (2) A planetary gear mechanism consisting of a sun gear, a planetary gear, and a ring gear, and an input shaft connected to the planetary gear;
A low-speed mechanical transmission system formed in the direction from the planetary gear to the ring gear and a high-speed mechanical transmission system formed in the direction from the planetary gear to the sun gear, with this planetary gear mechanism as the main body, and these mechanical transmission systems. The mechanical transmission system is constructed by connecting the input/output shaft of one fluid pump/motor near the low-speed transmission end and the input/output shaft of the other fluid pump/motor near the high-speed transmission end. a fluid transmission mechanism that forms a variable speed fluid transmission system in parallel with the above, a low speed clutch that connects and disconnects the low speed transmission end to the output shaft, and a low speed clutch that connects and disconnects the high speed transmission end to the output shaft. and a high-speed side clutch, and is configured to be able to select either the low-speed mode or the high-speed mode by switching both clutches in a reverse manner, wherein the outer periphery of the ring gear of the planetary gear mechanism is connected to the band brake. A continuously variable transmission characterized by using a brake drum as a braking surface of the mechanism.