JPH039157A - Continuously variable transmission - Google Patents

Abstract

PURPOSE:To achieve the stepless condition in an existing stepped automatic transmission by providing an actuator, which controls a friction element possible to control the connection condition of planetary gears elements, and an electronic control unit which commands action of the actuator so that target speed change ratio agrees with the actual speed change ratio. CONSTITUTION:The actual speed change ratio is calculated from signals of input and output shaft speed sensors 22, 24 and a throttle opening sensor 26, while target speed change ratio is determined from a specific output shaft speed and a throttle opening. When planetary gears are considered as a stepped transmission in the target speed change ratio, in the case of the first to second speed change ratio, when a pressure of oil in a clutch C2 and a servo relay chamber S/R is decreased to 0 by solenoid valves 16, 20 and when a pressure of oil in a servo apply chamber S/A is duty ratio-controlled by a solenoid valve 18, a brake B2 is controlled to a predetermined slip condition, and predetermined speed change ratio between the first and second speed changes is realized. Similarly in the case of the target speed change ratio between the second and third speed changes, the speed change ratio can be continuously changed.

Description

[Detailed description of the invention] (b) Industrial application field The present invention relates to a continuously variable transmission.

(B) Conventional Technology Automatic transmissions are classified into stepped automatic transmissions and continuously variable transmissions from the viewpoint of whether continuous control of the gear ratio is possible. For example, a stepped automatic transmission is disclosed in Japanese Patent Application Laid-Open No. 62-6204.
As shown in Japanese Patent No. 7, a planetary gear mechanism is used, and by switching the connection state of the gear mechanism using a clutch and a brake, the first to fourth gears are realized.

On the other hand, as a continuously variable transmission, for example, JP-A-61-105
There is a V-belt type as shown in Japanese Patent No. 351. That is, a V-belt is wound between two V-boolis with variable groove spacing. ■By controlling the groove interval of the pulley, the gear ratio can be changed continuously.

(C) Problems to be Solved by the Invention However, in a stepped automatic transmission, once the vehicle speed and gear position are determined, the engine rotational speed is uniquely determined, and it is difficult to obtain ideal power performance from the engine. However, there is a problem in that it is difficult to change the speed and that gear change shock occurs.

Continuously variable transmissions, on the other hand, do not have the above problems, but switching from conventional stepped automatic transmissions to continuously variable transmissions requires a large amount of development man-hours and costs, and production New, dedicated equipment will also need to be installed.

The present invention aims to solve these problems.

(d) Means for Solving the Problems The present invention solves the above problems by realizing a continuously variable transmission using a planetary gear device. That is, the continuously variable transmission according to the present invention includes an input shaft (I), an output shaft (0),
A planetary gear device (Go) is provided between the input shaft and the output shaft.
), a friction element (C+, C2, B+, B2) that can control the connection state of each element of the planetary gear device, and an operating state of the friction element in a fully engaged state, a completely released state, and a sliding state of an arbitrary ratio. Actuator to control (16,1
8, 20), an electronic control device (30) that outputs a signal instructing the operation of the actuator, and an input shaft rotational speed sensor (22) that detects the rotational speed of the input shaft or a rotating member that rotates in a predetermined relationship with the input shaft. ) and an output shaft rotation speed sensor (24) that detects the rotation speed of the output shaft or a rotating member rotating in a predetermined relationship with the output shaft, and the electronic control device includes:
It is configured to output a signal instructing the actuator to operate so that the target speed ratio commanded by the actuator matches the actual speed ratio obtained by the signals from the input shaft rotational speed sensor and the output shaft rotational speed sensor. Note that the symbols in parentheses indicate corresponding members in the embodiments described later.

(E) Effect When the predetermined friction element is in a completely released state, the first gear ratio is achieved, and when the friction element is in a fully engaged state, the second gear ratio (which is smaller than the first gear ratio) is achieved. If achieved, the gear ratio can be continuously changed from the first gear ratio to the second gear ratio in the following manner. In other words, the friction element is changed from a fully released state to, for example, a 1/2 slip state (if the friction element is a brake, a state in which the rotating member is braked to a rotation speed that is 1/2 of that in the fully released state).
Then, the gear ratio becomes an intermediate gear ratio between the first gear ratio and the second gear ratio. The smaller the slippage of the friction element is, the closer the gear ratio is from the first gear ratio to the second gear ratio. Therefore, by setting the operating state of the friction element to a predetermined sliding state using the actuator, a desired speed ratio between the first speed ratio and the second speed ratio can be realized. This makes it possible to steplessly change the speed between the maximum speed ratio and the minimum speed ratio that can be realized when the planetary gear device is used as a stepped automatic transmission.

(F) Embodiments Hereinafter, embodiments of the present invention will be described based on FIGS. 1 to 4 of the accompanying drawings.

FIG. 1 shows a schematic diagram of the power transmission mechanism of a continuously variable transmission. This power transmission mechanism consists of an input shaft 1 that transmits rotational force from an engine output shaft E via a torque converter T/C, and an output shaft 0 that transmits driving force to a final drive device.
, a planetary gear set G consisting of a first planetary gear set 01 and a second planetary gear set G2. , clutch C2, clutch C1, brake B2 Brake B1 and one-way clutch oWC
have. The first planetary gear set G1 is a carrier PCI that supports a sun gear S, an internal gear R2, and a pinion gear P that meshes with both gears S1 and R at the same time.
The planetary gear set G2 includes a sun gear Sz, an internal gear R2, and both gears Sz and R.
2 and a carrier PC2 that supports a pinion gear P2 that meshes with the carrier PC2 at the same time. Each component is connected as shown. The brake B2 has a servo apply chamber S/A for engaging it, and a servo release chamber S/R for releasing it (this is a servo apply chamber S/A).
/A).

The above power transmission mechanism operates each element (S+, S2, R1,
Rz, pcl and PCz) can be changed, thereby changing the rotational speed of the output shaft O with respect to the rotational speed of the input shaft I.
By changing the rotational speed of the motor, continuously variable speed can be realized as described below.

Figure 2 shows the hydraulic circuit. The oil pressure discharged by the oil pump 10 is regulated by a line pressure regulating valve 12,
It is then distributed by manual valve 14. clutch C
1 is always supplied with line pressure during forward movement. Clutch C2, servo apply chamber S/A and servo release chamber S
/R is supplied with a predetermined hydraulic pressure as described below through solenoid valves 16, 18 and 20, respectively. The operation of solenoid valves 16, 18 and 20 is controlled by electronic control unit 30. That is, the solenoid valves 16, 18 and 20 have their duty ratios controlled, and output oil pressure according to the applied electric signal to the clutch C2, the servo apply chamber S/A, and the servo release chamber S/R, respectively.

As shown in FIG. 3, signals from an input shaft rotation speed sensor 22, an output shaft rotation speed sensor 24, and a throttle opening sensor 26 are manually input to the electronic control device 30.

Based on these input signals, electronic control unit 30 outputs signals that actuate solenoid valves 16, 18 and 20. This control is executed according to the control flow shown in FIG. First, the input shaft rotation speed sensor 22, the output shaft rotation speed sensor 24, and the throttle opening sensor 26.
The actual gear ratio (actual gear ratio IR) is calculated from the input shaft rotation speed and output shaft rotation speed, and the target gear ratio (target gear ratio IT) is calculated from the specific output shaft rotation speed and throttle opening. ) to determine. The target gear ratio Ia is the planetary gear unit G. When considered as a stepped transmission, the first speed ~
It is determined whether the gear ratio is between 2nd gear or between 2nd gear and 3rd gear, and if the gear ratio is between 1st gear and 2nd gear, the solenoid valves 16 and 20 are The hydraulic pressure in clutch C2 and servo release chamber S/R is set to 0 (solenoid valves 16 and 20 are turned off), and the servo apply chamber S/R is set to 0.
The duty ratio of the oil pressure of A is controlled by a solenoid valve 18. That is, when the target gear ratio IT is smaller than the actual gear ratio IFI, the oil pressure in the servo apply chamber S/A is lowered, and conversely, when the target gear ratio IT is smaller than the actual gear ratio IFI. If it is larger than , the oil pressure in the servo apply chamber S/A is increased. As a result, the brake B2 is controlled to a predetermined slip state, and a predetermined gear ratio between the first speed and the second speed is realized. On the other hand, when the target gear ratio is between 2nd and 3rd gears, line pressure is applied to the servo apply chamber S/A (solenoid valve 18 is on), and clutch C2 and The duty ratio of the oil pressure in the servo release chamber S/R is controlled by solenoid valves 16 and 20. That is, when the target gear ratio IT is smaller than the actual gear ratio IR, the oil pressure of the clutch C2 is decreased and the oil pressure of the servo release chamber S/R is increased. Conversely, when the target gear ratio IT is larger than the actual gear ratio (2), the oil pressure of the clutch C2 is increased and the oil pressure of the servo release chamber S/R is decreased. This allows the 1st to 3rd speeds to be considered as a stepped transmission.
For example, if the target gear ratio is gradually changed from the value of 1st gear to the value of 3rd gear, the gear ratio will change continuously accordingly. I will continue to do so.

In the above embodiment, a planetary gear device with three forward speeds was used when considered as a stepped transmission. Of course, it is also possible to realize a continuously variable transmission using the following.

(g) As described in detail, according to the present invention, the gear ratio is continuously changed by controlling the sliding state of the friction element that controls the connected state of the planetary gear device. , it becomes possible to construct a continuously variable transmission using an existing stepped automatic transmission.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a framework of a continuously variable transmission, FIG. 2 is a diagram showing a hydraulic circuit, FIG. 3 is a diagram showing an electronic control device, and FIG. 4 is a diagram showing a control flow. ■... Input shaft, O... Output shaft, G,... Planetary gear set, C,, C2, clutch, B,, B2... Brake, 16. -18゜20... Solenoid valve (actuator), 22... Input shaft rotation speed sensor 24
...Output shaft rotational speed sensor, 30...Electronic control device.

Claims (1)

[Claims] An input shaft, an output shaft, a planetary gear device provided between the input shaft and the output shaft, a friction element that can control the connection state of each element of the planetary gear device, and an operating state of the friction element in a fully engaged state. , an actuator that controls the fully released state and a sliding state of an arbitrary ratio, an electronic control device that outputs a signal instructing the actuator to operate, and detects the rotational speed of the input shaft or a rotating member that rotates in a predetermined relationship with the input shaft. The electronic control device has an input shaft rotation speed sensor that detects the rotation speed of the output shaft or a rotating member that rotates in a predetermined relationship with the output shaft, and the electronic control device has a target gear ratio that it commands, A continuously variable transmission configured to output a signal instructing the operation of an actuator so that an actual speed ratio obtained by signals from an input shaft rotational speed sensor and an output shaft rotational speed sensor coincide with each other.