JP2677025B2 - Hydraulic control device for continuously variable transmission for vehicles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic control device for a continuously variable transmission, and more particularly to a hydraulic pressure detection structure for hydraulic control.

[0002]

2. Description of the Related Art As a so-called continuously variable transmission, a belt is laid between a pair of pulleys, and the groove width of the pulley on which the belt is hung is changed to wind the belt around the driving side and the driven side. There is a structure in which the gear ratio is made variable by changing. By the way, as one of the mechanisms for changing the groove width of the above-mentioned pulley, there is a structure for axially displacing a movable conical plate facing one fixed conical plate constituting the pulley by using a hydraulic mechanism. An example of the above-mentioned hydraulic mechanism is, for example, the one described in Japanese Patent Laid-Open No. 59-19755. In this structure, oil from an oil pump set to a predetermined pressure by a pressure regulating valve is supplied to a driven pulley. The oil pressure is supplied to the hydraulic cone side of the movable conical disc, and the oil is provided to the movable conical disc of the drive side pulley via the gear ratio control valve to which the oil passage extended from the pressure regulating valve is connected. The groove width of the pulley is changed by introducing it to the chamber or by discharging the oil in the drive-side pulley hydraulic chamber to the drain circuit via the gear ratio control valve.

[0003]

By the way, in order to obtain the required gear ratio in the above-mentioned speed change mechanism,
When setting the groove width of the drive side pulley, the line supplied to the hydraulic chamber of the driven side pulley so that the driven side pulley has an appropriate belt clamp to maintain the frictional engagement between the belt and the conical plate. The pressure is regulated in relation to the transmitted torque. For this reason, in the conventional example, the line pressure is tracked and detected by the hydraulic pressure sensor arranged in the hydraulic chamber on the driven pulley side, and the detected hydraulic pressure and the target line pressure are compared to determine the line pressure. When the actual value of is greater than the target value, the line pressure is reduced, and when the actual value of the line pressure is less than the target value, the line pressure is increased by feedback control. There is. However, the oil pressure sensor is relatively expensive, and it is costly to use only for such belt clamping force optimization.

Therefore, an object of the present invention is to solve the above-mentioned problems in the conventional hydraulic mechanism, particularly in the hydraulic pressure detection structure.
Cost performance can be improved by using two hydraulic pressure sensors for two types of hydraulic pressure detection, high precision belt clamping force can be obtained, and hydraulic pressure control for operating the forward stage achievement hydraulic actuator or reverse stage achievement actuator can be performed. To obtain a hydraulic control device for a continuously variable transmission.

[0005]

In order to achieve this object, the present invention provides an input shaft to which a driving force from an engine is input via a torque converter, a drive pulley provided on the input shaft, and the input shaft. Before and after switching between forward and reverse gears of the vehicle, an output shaft arranged in parallel with the driven shaft, a driven pulley provided on the same output shaft, a continuously variable transmission unit consisting of a drive belt spanned between the pulleys. In a hydraulic control device for a continuously variable transmission for a vehicle, which includes a forward switching unit, a hydraulic actuator for achieving a forward speed that achieves the forward speed, and a hydraulic actuator for achieving a reverse speed that achieves the reverse speed, A regulator valve that regulates the discharge oil to a predetermined line pressure, a modulator valve that further reduces the line pressure to a predetermined pressure for supplying both hydraulic actuators, and a modulator valve and An actuator pressure control valve that is arranged in an oil passage that connects both hydraulic actuators and that controls the hydraulic pressure supply state to both hydraulic actuators, and the actuator pressure control valve that is switched by a shift lever that is arranged in the vehicle interior. A manual valve capable of supplying the discharge pressure from the hydraulic pressure actuator for achieving the forward speed or the actuator for achieving the reverse speed, a solenoid valve for controlling the regulator valve according to the operating state of the vehicle, and the actuator pressure controller. A hydraulic pressure sensor disposed in an oil passage connecting the valve and the manual valve, and when the hydraulic pressure sensor detects that the modulator discharge pressure is equal to or lower than the predetermined pressure, the hydraulic pressure sensor output value It is characterized in that the solenoid valve is controlled accordingly.

[0006]

According to the present invention, the position of the manual valve for switching the oil passage of either the forward stage achievement hydraulic actuator or the reverse stage achievement actuator is set according to the operating state set by the select lever. Then, the discharge pressure from the actuator pressure control valve, which is guided to the forward stage achievement hydraulic actuator or the reverse stage achievement actuator via the manual valve, can be directly measured. In addition, if the line pressure supplied to the actuator pressure control valve becomes less than the maximum clutch pressure or maximum brake pressure after the forward stage achievement hydraulic actuator or the reverse stage achievement actuator is completely engaged, the actuator pressure control valve Since the discharge pressure (clutch pressure or brake pressure) from is equal to the line pressure, the hydraulic pressure in the hydraulic chamber of the driven pulley can be measured by this hydraulic pressure sensor.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the present invention will be described in detail with reference to FIGS. FIG. 1 is a hydraulic circuit diagram for explaining the configuration of the hydraulic control mechanism according to the embodiment of the present invention.

Before describing this circuit, a continuously variable transmission using this circuit will be described below with reference to FIG. That is, the continuously variable transmission used in this embodiment is connected to the output shaft 1A of the engine 1 via the fluid coupling 2. The fluid coupling 2 has a lock-up mechanism, and controls the hydraulic pressure in the hydraulic chamber 2A of the damper clutch to frictionally engage the input-side pump impeller 2B and the output-side turbine runner 2C. The frictional engagement relationship is released by or separately. The fluid coupling 2 described above is provided with an output shaft 2D integrally rotatable on the output side thereof, and the output shaft 2D is connected to a forward / reverse switching mechanism 3 for switching between forward and reverse stages. . The forward / reverse switching mechanism 3 described above includes a planetary gear mechanism 4 having a well-known structure, a forward clutch 5 as a hydraulic actuator for achieving a forward speed, and a reverse brake 6 as a hydraulic actuator for achieving a reverse speed. By changing the engagement of the forward drive clutch 5 or the reverse drive brake 6, the rotation direction of the rotary shaft 4A connected to the output side of the planetary gear mechanism 4 is switched. On the other hand, a drive pulley 7 which is one of the main parts of the continuously variable transmission is provided on the rotating shaft 4A described above. This drive pulley 7 has a rotary shaft 4A.
A fixed conical plate 7A that is integral with the fixed conical plate 7A, and a movable conical plate 7B that is inserted into the boss portion of the fixed conical plate 7A at a position facing the fixed conical plate 7A and is movable in the axial direction. A hydraulic chamber 7C is formed on the back side of the. The hydraulic chamber 7C is composed of first and second chambers 7Cl and 7C2. Further, the drive pulley 7 is configured to interlock a driven pulley 9 with a belt 8. The driven pulley 9 is located on the output side when the driving pulley 7 is the input side of the rotational force, and the driven pulley 9 has a movable cone. A fixed conical plate 9A is arranged on the side facing the plate 7B, and a movable conical plate 9B is inserted into the boss portion of this fixed conical plate 9A so as to be movable in the axial direction. Also in the driven pulley 9 described above, the hydraulic chamber 9C is formed on the back surface of the movable conical plate 9B, and the groove width can be changed in cooperation with the drive pulley 7 side by the hydraulic control in the hydraulic chamber 9C. It is designed to generate a clamping force. Further, a centrifugal balance chamber 9D is provided on the back surface of the driven pulley side hydraulic chamber 9C so as to cancel the centrifugal hydraulic pressure of the hydraulic chamber 9C. A driven shaft 10 is integrally provided on the fixed conical plate 9A of the driven pulley 9, and a drive gear 11 is attached to the driven shaft 10. The drive gear 11 is an idle gear 12,
The driving force can be transmitted to the final gear 16 via 13. Then, the driving force is transmitted to the differential gear mechanism 17, and finally the engine driving force is output to the output shaft 1.
4 and 15 are transmitted.

On the other hand, the oil pressure control mechanism for the drive pulley 7 and the driven pulley 9 to the hydraulic chambers 7C, 9C in the above-mentioned continuously variable transmission is shown in FIG. The mode of each valve when the position of a certain select lever is set to the neutral state (N) is shown. In the figure,
The symbol x indicates a drain path. This hydraulic control structure controls the oil pump 18, the line pressure regulating valve 19 that regulates the hydraulic pressure to the hydraulic chamber 9C of the driven pulley 9, the line pressure control solenoid valve 20A, the gear ratio control valve solenoid valve 20B, and the gear ratio. Gear ratio control valve 21,
Clutch control pressure switching valve 22, damper clutch control valve 23, clutch pressure control valve 24 as an actuator pressure control valve, operating mode selection manual valve 25 and solenoid valve 2.
6 and so on.

The oil pump 18 described above includes a tank 27.
The oil inside is sucked through the strainer 28 to the oil passage 29.
The oil discharged from the oil passage 29 is introduced into the port 19A of the line pressure regulating valve 19 and adjusted to a predetermined pressure as the operating line pressure of each valve. The oil passage 29 includes a hydraulic chamber 9C of the driven pulley 9, a port 21A of the gear ratio control valve 21, a port 23A of the damper clutch control valve 23, a port 30A of the control pressure modulator valve 30, and a clutch pressure modulator valve 31. It is also connected to the port 31B. The control pressure modulator valve 30
The operating pressure regulated by the solenoid valves 20A, 20
The supply pressure is communicated with B and 26, and is a supply pressure for generating a solenoid control pressure by the duty operation of each solenoid valve.

The line pressure control solenoid valve 20A
Acts on the line pressure regulating valve 19 to control the line pressure, and controls the belt clamping force on the driven pulley 9 side. The gear ratio control solenoid valve 20B is
It acts on the gear ratio control valve 21, guides the line pressure to the drive pulley hydraulic chamber, discharges oil from the hydraulic chamber,
The displacement amount of the movable conical disc 7B in the drive pulley 7 is controlled. And both solenoid valves 20
A and 20B are, for example, engine speed, load, vehicle speed,
Also, the groove width on the pulley side is adjusted in order to set the belt clamp force and the gear ratio that enable the transmission of the engine side torque based on the vehicle operation information such as the detection value of the hydraulic pressure sensor 35 described later. ing.

On the other hand, the clutch control pressure switching valve 22 is switched by the differential pressure between the modulator pressure of the clutch pressure modulator valve 31 and the forward clutch operating pressure described later.
Is configured to switch the control pressure of the solenoid valve 26 to a position in which it can be guided to either the clutch pressure control valve 24 side or the damper clutch pressure control valve 23 side described above.

The operation state of the clutch control pressure switching valve 22 is connected to the solenoid valve 26 and the clutch pressure control valve 24 so that the hydraulic pressure supplied to the forward clutch 32 and the reverse brake 33 can be controlled. When set to the position, the solenoid valve 26 changes the modulator pressure introduced into the clutch pressure control valve 24 via the oil passage 31A to the position switching state of the operation mode selection manual valve 25 described later and the hydraulic sensor 35 described later. The pressure is adjusted in accordance with the detected value of 1 and the hydraulic pressure is introduced into the forward clutch 32 or the reverse brake 33 via the operation mode selection manual valve 25.

The above-mentioned operation mode selecting manual valve 25 is adapted to set an oil passage to the forward clutch 32 and the reverse brake 33 in conjunction with a select lever operated by the driver, and is shown in the neutral (illustrated). When the spool moves to the right side from the (N) position, in other words, in the forward (D) direction, it connects the oil passage between the clutch pressure control valve 24 and the forward clutch 32, and the spool moves to the neutral ( When moving in the reverse direction from the N) position, in other words, moving in the reverse (R) direction, an oil passage between the clutch pressure control valve 24 and the reverse brake 33 is set.

On the other hand, a hydraulic pressure sensor 35 is provided in the oil passage 34 located between the above-mentioned control pressure discharge port from the clutch pressure control valve 24 and the introduction port of the operation mode selection manual valve 25. There is. The hydraulic pressure sensor 35 detects the hydraulic pressure (clutch pressure) of the oil passage 34 during manual operation such as “N → D” and “N → R”.
Based on this detected value, the duty operating state of the solenoid 26 is feedback-controlled. Therefore, “N → D” and “N → R” control without shock can be obtained. On the other hand, after the forward clutch 32 is completely engaged in response to the increase in the hydraulic pressure supplied from the clutch pressure control valve 24, the circuit of the clutch control pressure switching valve 22 is switched and the solenoid valve 26 becomes the damper clutch control valve 23. The solenoid valve 26 becomes able to control the damper clutch control valve 23 by switching to a position in which the oil passage to is connected. At this time, the oil passage 34
Is the hydraulic pressure regulated by the clutch pressure modulator valve 31 and the clutch pressure control valve 24, but the pressure in the oil passage 29 is higher than the maximum regulated pressure by the clutch pressure modulator valve 31 and the clutch pressure control valve 24. When the pressure is low, the pressure in the oil passage 34 is the same as the line pressure in the oil passage 29. Therefore, in this state, the hydraulic pressure sensor 35 detects the line pressure.

The line pressure detection for setting the groove width on the pulley side described above can be performed for the following reason. During start-up acceleration or overtaking acceleration, the throttle opening is large, in other words, the engine torque is large and the gear ratio is also large, so frictional engagement between the pulley and the belt, that is, the belt clamping force is It is necessary to increase the line pressure in order to make it strong, but such a state is relatively short. On the other hand, during constant speed operation, the engine torque described above is small and the belt clamping force, that is, the line pressure may be low. It is necessary to prevent the excessive clamping force on the belt and, conversely, to finely adjust the belt clamping force so that the belt does not slip. And, in actual traveling, such a constant speed operation time is long. For this reason, during constant speed traveling, adjustment control of the belt clamping force is more important than during acceleration traveling, so line pressure detection for this control is necessary. Therefore, the oil pressure sensor 3 arranged in the oil passage 34 described above.
When the line pressure set by the line pressure control solenoid valve 20A and the line pressure regulating valve 19 is low as in the case of traveling at a constant speed, specifically, 5 is less than or equal to the maximum regulated pressure by the clutch pressure control valve 24. In this case, since the output pressure of the clutch pressure control valve 24 (= the pressure of the oil passage 34) is equal to the line pressure, the line pressure applied to the hydraulic chamber 9C on the driven pulley 9 side can be detected. Therefore, in the present embodiment, when the control unit (not shown) determines that the output of the hydraulic pressure sensor is lower than the maximum regulated pressure by the preset clutch pressure control valve 24, the hydraulic pressure sensor 35 outputs the above-mentioned pressure. The detected pressure is taken in and the line pressure is feedback-controlled.

Next, the operation of this embodiment will be described.
The oil discharged from the oil pump 18 is set to a predetermined line pressure by the line pressure adjusting valve 19 and the line pressure controlling solenoid valve 20A. On the other hand, this line pressure is further reduced by the control pressure modulator valve 30 to be set to a predetermined operating pressure and introduced into one end of the gear ratio control valve 21. On the other hand, the control pressure set by the solenoid valve 20B for gear ratio control is introduced to the other end of the gear ratio control valve 21, and the movement amount of the spool of the valve is set according to the difference from the above-mentioned operating pressure. , Supply of oil to the hydraulic chamber 7C of the drive pulley 7 or the drive pulley 7
The displacement of the movable conical plate in each pulley is controlled by discharging the oil from the hydraulic chamber 7C.

The line pressure regulated by the line pressure regulating valve 19 is introduced into the clutch control pressure switching valve 22 and the clutch pressure control valve 24 via the clutch pressure modulator valve 31. That is, when the line pressure is higher than the predetermined pressure by the clutch pressure modulator valve 31, the line pressure is reduced to the predetermined pressure, and when the line pressure is equal to or lower than the predetermined pressure, the pressure is introduced as it is. In the clutch control pressure switching valve 22, the movement amount of the spool of the clutch pressure modulator valve 31 is set according to the difference between the modulation pressure by the clutch pressure modulator valve 31 and the forward clutch operating pressure, and the solenoid valve 26 is controlled. It is set to which oil passage of the damper clutch control valve 23 and the clutch pressure control valve 24 the pressure is guided. By the way, a hydraulic pressure sensor 35 is arranged midway in the oil passage that directly connects the clutch pressure control valve 24 and the manual valve 25, and the hydraulic pressure sensor 35 detects the pressure of the oil projected from the clutch pressure control valve 24. It
This detected value is the manual valve 2 for operating mode selection.
The clutch pressure control valve 2 according to the setting switching position of 5
The pressure data is used to control the duty of the solenoid valve 26 that controls No. 4.

Next, the forward clutch pressure for engaging the forward clutch increases due to the shift to the forward stage such as "N → D" so that the control pressure of the solenoid valve 26 can control the damper clutch control valve 23. Think about when
In particular, when the vehicle is traveling at a constant speed, the line pressure is regulated by the clutch pressure control valve 24 to be lower than the maximum regulated pressure. The hydraulic chamber 9 of the driven pulley 9
It becomes possible to directly detect the line pressure applied to C.

[0020]

As described above, according to the present invention, the actuator pressure control of the oil passage for introducing the discharge pressure from the actuator pressure control valve to the forward stage achievement hydraulic actuator or the reverse stage achievement actuator via the manual valve. Since the hydraulic pressure sensor is arranged between the valve and the manual valve, the hydraulic pressure for operating the forward stage achievement hydraulic actuator or the reverse stage achievement actuator can be feedback-controlled based on the hydraulic sensor output value. Therefore, for example, the shift shock when switching the manual valve from the neutral position to the forward speed or the reverse speed can be lightened. Further, since the hydraulic pressure of the pressure regulating circuit of the actuator pressure control valve can be regarded as the line pressure applied to the driven pulley side and can be detected when traveling at a constant speed, it is particularly important to set an appropriate clamping force for the belt. During steady running, feedback control can be performed based on the output value of this hydraulic sensor. As described above, the cost performance can be improved by using one hydraulic pressure sensor for two types of hydraulic pressure detection, and the belt clamping force with high accuracy can be obtained.
Also, when it is particularly important to set the proper clamping force for the belt on the driven pulley side, it is at low line pressure such as during steady running and not so important at high line pressure, so only at low line pressure. It suffices to be able to detect, and it is possible to reduce the need to prepare an expensive high-pressure hydraulic sensor.
As a result, since the sensitivity of the hydraulic pressure sensor may be adjusted to the low hydraulic pressure side described above, the hydraulic pressure detection accuracy can be improved. Furthermore, since it is possible to provide a plurality of hydraulic pressure detection functions even if the number of hydraulic pressure sensors is reduced, it is possible to reduce mechanical costs related to hydraulic pressure detection.

[Brief description of the drawings]

FIG. 1 is a hydraulic circuit diagram for explaining a hydraulic control mechanism according to an embodiment of the present invention.

FIG. 2 is a model diagram showing an example of the structure of a continuously variable transmission to which the control mechanism shown in FIG. 1 is applied.

[Explanation of symbols]

 l Engine 2 Fluid coupling 7 Drive pulley 7B Movable conical plate 8 Belt 9 Driven pulley 9B Movable conical plate 18 Oil bomb 19 Line pressure regulator valve 24 Clutch pressure control valve 25 Manual valve for operating mode selection 29 Oil passage from line pressure regulator valve 34 Oil Path to Operation Mode Select Manual Valve 35 Oil Pressure Sensor

Claims (1)

(57) [Claims] 1. An input shaft to which a driving force from an engine is input via a torque converter, a drive pulley provided on the input shaft, an output shaft arranged in parallel with the input shaft, and an output shaft on the output shaft. A continuously variable transmission consisting of a driven pulley installed on the vehicle and a drive belt spanned between both pulleys, a forward / reverse switching unit that switches between forward and reverse gears of the vehicle, and achievement of the forward gear that achieves the above-mentioned forward gear In a hydraulic control device for a continuously variable transmission for a vehicle, comprising: a hydraulic actuator for a vehicle and a hydraulic actuator for achieving a reverse gear, a regulator for adjusting a discharge oil from an oil pump to a predetermined line pressure. A valve, a modulator valve that further reduces the line pressure to a predetermined pressure for supplying the hydraulic actuators, and an oil passage that connects the modulator valve and the hydraulic actuators. Is an actuator pressure control valve for controlling the hydraulic pressure supply state to the hydraulic actuator, is switched by the shift lever disposed in the vehicle interior,
A manual valve capable of supplying the discharge pressure from the actuator pressure control valve to the forward stage achievement hydraulic actuator or the reverse stage achievement actuator, and a solenoid valve for controlling the regulator valve according to the operating state of the vehicle, When a hydraulic pressure sensor provided in an oil passage connecting the actuator pressure control valve and the manual valve is provided, and the hydraulic pressure sensor detects that the modulator discharge pressure is equal to or lower than the predetermined pressure, A hydraulic control device for a continuously variable transmission for a vehicle, which controls the solenoid valve according to an output value of a hydraulic sensor.