JPH08178049A - Speed change control device for belt type cvt - Google Patents

Abstract

PURPOSE: To prevent the occurrence of an abrupt speed change by sealing the operating oil in an input pulley piston chamber when a failure occurs on an electronic control device, etc. CONSTITUTION: The housing of a speed change control valve 40 is provided with a line pressure port 40a, an input pulley piston pressure port 40b, a drain port 40c, and a notch 40e. A spool 41 having three lands 41a, 41b, 41c is coupled in the valve 40, and the spool 41 is displaced by the thrust of a spring 42 and a solenoid 43. When the solenoid 43 is set to the nonoperational state or the maximum operational state, the input pulley piston pressure port 40b is cut off from the line pressure port 40a and the drain port 40c, the operating oil is sealed in an input pulley piston chamber, a speed change is made so that the reduction gear ratio is gradually increased, and the occurrence of an abrupt speed change is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a belt type CVT shift control device.

[0002]

2. Description of the Related Art As a conventional belt-type CVT shift control device of this type, there is one disclosed in, for example, Japanese Patent Laid-Open No. 58-81258. This conventional example is a control device for a V-belt type continuously variable transmission in which a V-belt is wound between a drive pulley and a driven pulley in which the distance between V-shaped grooves is variable according to the hydraulic pressure in the pulley cylinder chamber and the transmission is performed. When the line pressure regulator valve and the shift control valve are controlled by the torque motor for the line pressure regulator valve and the torque motor for the shift control valve operated by the electronic control unit, and the torque motor for the line pressure regulator valve is in the non-operating state. Adjust the line pressure to the highest level,
The hydraulic pressure in the driven pulley chamber is set to be the highest and the hydraulic pressure in the drive pulley chamber is set to be the lowest when the shift control torque motor is in the non-operating state.

[0003]

However, the conventional belt type C as disclosed in the above-mentioned JP-A-58-81258 is used.
In the VT shift control device, the reduction ratio is maximized when the electronic control device of the shift control valve is in the non-operating state, and is minimized when the electronic control device is in the maximum operating state. When a failure occurs in the control device or the like, the speed is rapidly changed so that the speed reduction ratio approaches the maximum or minimum. For this reason, when the vehicle is suddenly shifted in the direction of increasing the reduction ratio during traveling, the engine brake may suddenly increase to cause the driver to feel uncomfortable, or the engine may overspeed to accelerate mechanical deterioration. There is a problem.
In addition, when the gear ratio suddenly shifts to a smaller value,
If the driving force increases during a sudden gear shift and an unexpectedly large driving force change occurs during traveling, there is a problem that the driver may feel uncomfortable.

The present invention has been made in view of such a conventional problem, and when the electronic control unit is in a non-operating state or a maximum operating state, a port to an input pulley piston chamber for controlling a gear ratio is provided. By shutting off from the line pressure port and the drain port and confining the hydraulic oil in the input pulley piston chamber, it is possible to prevent a sudden gear shift when a failure occurs in the electronic control unit, The purpose is to solve the above problems.

[0005]

To this end, the structure of claim 1 of the present invention has pistons for applying a force to the input and output pulleys in the direction of narrowing the sheave spacing of the pulleys, and to the output pulley piston chamber. Line pressure is introduced, and the supply and discharge of hydraulic oil to and from the input pulley piston chamber for gear ratio control is performed by a gear control valve that regulates the line pressure and the amount of communication with the drain by a signal from electronic control. Belt type CV
In the speed change control device of T, when the electronic control device is in the non-operating state or the maximum operating state, the port to the input pulley piston chamber is shut off from the line pressure port and the drain port, and the working oil is confined in the input pulley piston chamber. It is characterized by doing so.

In the above description, the amount of communication between the port to the input pulley piston chamber and the line pressure port and the drain port is adjusted by one land of the spool, and in the spool axial direction with respect to the land. The structure of the shift control valve is simplified by providing other lands on the front and rear and arranging so that each of the other lands blocks the line pressure port or the drain port at each end of the range in which the spool is displaced. It is preferable in order to reduce costs.

[0007]

According to the first aspect of the present invention, the belt type C
In the VT shift control device, when the hydraulic fluid is supplied to and discharged from the input pulley piston chamber for gear ratio control by a shift control valve that regulates the line pressure and the amount of communication with the drain by a signal by electronic control. In addition, when the electronic control unit is in the non-operating state or the maximum operating state, the port to the input pulley piston chamber is cut off from the line pressure port and the drain port, and the working oil is trapped in the input pulley piston chamber. When the electronic control unit is in the non-operating state or the maximum operating state, the input pulley piston pressure shifts in the direction in which the reduction ratio gradually increases in response to leakage from the seal, and the electronic control unit fails. It is possible to prevent a sudden shift from occurring in the case of occurrence of.

[0008]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a diagram showing the configuration of a first embodiment of a belt type CVT shift control device of the present invention, in which reference numeral 40 denotes a shift control valve. The housing of the shift control valve 40 includes a line pressure port 40a and an input pulley piston pressure port 40.
b, a drain port 40c, and a notch (hereinafter referred to as a notch) 40e for mitigating a flow rate change, which is positioned before and after the input pulley piston pressure port 40b in the spool axial direction, are provided. The spool 41 of the valve is fitted. The spool 41 is pressed and urged by a spring 42 from the left in the figure, and
It is pressed from the right direction in the figure by the plunger of the shift control valve solenoid 43 as an electronic control device. The spool 41 has a land 4 provided substantially in the center thereof.
1a and lands 41b and 41c located at the front and rear of the land 41a in the spool axis direction are provided, respectively.

Next, the operation of this embodiment will be described with reference to FIGS. The spool 41 is displaced to a position where the thrust force of the spring 42 pushing rightward in FIG. 1 (spring force of the spring 42) and the thrust force of the solenoid 43 pushing leftward in FIG. 1 are balanced. The solenoid 43 does not generate thrust when it is not operated, but generates thrust according to the current supplied when it is operated. In the state shown in FIG. 1, the input pulley piston pressure port 40b is connected to the line pressure port 4 by the land 41a.
0a and drain port 40c are blocked. For this reason, the input pulley piston (not shown) is hardly displaced, and a change in the gear ratio is hardly generated.

When the thrust of the solenoid 43 is gradually reduced from this state, the spool 41 is displaced to the right in FIG. 1, and the communication area of the input pulley piston pressure port 40b with the drain port 40c increases. . This allows
The hydraulic oil in the input pulley piston chamber (not shown) is discharged, the sheave space of the input pulley (not shown) is expanded, and the belt running diameter at the input pulley is reduced. Along with this, in the output pulley (not shown), the space between the sheaves is narrowed and the belt running diameter is increased, that is, the reduction ratio in the output pulley is increased. When the thrust of the solenoid 43 is further reduced, the spool 41 is further displaced to the right in FIG. 1, and when the thrust is near the minimum value, the spool 41 stops at the position shown in the upper half of FIG. At this position, the drain port 40c is closed by the land 41b of the spool 41, so that there is almost no change in the gear ratio again.

On the other hand, when the thrust of the solenoid 43 is gradually increased, the spool 41 is displaced to the left side in FIG.
The input pulley piston pressure port 40b is the line pressure port 4
The communication area with 0a increases. As a result, hydraulic oil is supplied to the input pulley piston chamber, the space between the sheaves of the input pulley is narrowed, and the belt running diameter at the input pulley is increased. Along with this, in the output pulley, the space between sheaves is expanded,
The belt running diameter is reduced, that is, the reduction ratio is reduced. When the thrust of the solenoid 43 is further increased,
The spool 41 is further displaced to the left side in FIG. 1, and when the thrust becomes close to the maximum value, the spool 41 stops at the position shown in the lower half of FIG. In this position, line pressure port 4
Since 0a is closed by the land 41c of the spool 41, there is almost no change in the gear ratio again. In the first embodiment, the communication area is the spool 41.
Notch 40e so that it changes gently with respect to the displacement amount of
Is provided.

In the first embodiment, a speed change control valve for regulating the supply / discharge of hydraulic oil to / from the input pulley piston chamber for speed ratio control is defined by a signal by electronic control to regulate the line pressure and the amount of communication with the drain. 40, when the shift control valve solenoid 43 as the electronic control device is in the non-operating state or the maximum operating state, the input pulley piston pressure port 40b is set to the line pressure port 40a and the drain port 4
Since the hydraulic oil is shut off from 0c and the hydraulic oil is confined in the input pulley piston chamber, when the shift control valve solenoid 43 is in the non-operating state or the maximum operating state, the input pulley piston pressure may be leaked from the seal. It is possible to prevent a rapid shift from occurring when a failure occurs in the shift control valve solenoid 43 or the like because the shift is performed in a direction in which the reduction ratio gradually increases. Therefore, unlike the above-described conventional example, there is no sudden increase in engine brake, mechanical deterioration of the engine, or large change in driving force during traveling. In addition, since the first embodiment has a simple structure and can be configured with a small number of parts, the degree of freedom in layout in the control valve is increased and the cost can be reduced.

FIG. 4 is a diagram showing the configuration of a second embodiment of the shift control device for a belt type CVT according to the present invention. In the second embodiment, instead of the shift control solenoid 43 of the first embodiment, a shift control solenoid 44 (for example, a duty solenoid or a proportional solenoid) that generates a signal pressure according to an electric signal is used as an electronic control device. , A signal pressure port 40d is additionally provided in the shift control valve 40, and the signal pressure port 40d and the solenoid 44 are communicated with each other by the solenoid pressure oil passage 45, and the thrust generated by the solenoid 44 is shift controlled via the signal pressure port 40d. It is introduced into the valve 40 to oppose the thrust of the spring 42.

In the second embodiment, the thrust of the shift control solenoid 44 is used in place of the thrust of the shift control solenoid 43 of the first embodiment, so that the same effect as the first embodiment is obtained. Is obtained.

FIG. 5 is a diagram showing the configuration of a third embodiment of the belt type CVT shift control device according to the present invention. In the third embodiment, when the pressure generated by the shift control solenoid 44, which is an electronic control device, is close to the maximum value (that is, when the solenoid 44 is in the maximum operating state) and near the minimum value ( That is, when the solenoid 44 is in the non-operating state), the function of shutting off the input pulley piston pressure port 50b from the line pressure port 50a and the drain port 50c and confining the working oil in the input pulley piston chamber is performed by the drain shutoff valve 60 and the input pulley. This is achieved by combining the piston oil passage cutoff valve 70 with the shift control valve 50.

That is, the shift control valve 5 of the third embodiment
0 has substantially the same structure as the shift control valve 40 of FIG. 4 of the second embodiment described above, except that the spool 51 has only two lands (the second embodiment has three lands). The difference from the second embodiment is that no notches are provided at the front and rear of the input pulley piston pressure port 50b in the spool axial direction. The drain port 50c of the shift control valve 50 communicates with the port 60a of the drain cutoff valve 60 by an oil passage 65.

The housing of the drain shutoff valve 60 is provided with a drain port 60b and a signal pressure port 60c in addition to the port 60a, and the spool 61 in the housing has a thrust force for pushing the spring 62 to the right in FIG. 5 according to the signal pressure supplied to the signal pressure port 60c.
It is displaced to a position that balances with the thrust that pushes in the center left direction. When the spool 61 is in the position shown in the lower half of FIG. 5 (when the signal pressure is high), the port 60a and the drain port 60b
In the case of the position shown in the upper half of FIG. 5 (when the signal pressure is small), the port 60a and the drain port 60b are in communication with each other because the connection between the ports 60a and 60b is blocked. The hydraulic oil in the drain port 50c of the shift control valve 50 is drained.

The input pulley piston pressure port 50b of the shift control valve 50 is connected to the port 70a of the input pulley piston oil passage cutoff valve 70 by an oil passage 75. The housing of the input pulley piston oil passage shutoff valve 70 is provided with a port 70b and a signal pressure port 70c in addition to the port 70a, and a spool 71 in the housing has a thrust force that pushes the spring 72 to the right in FIG. , Signal pressure port 7
It is displaced to a position where the thrust force pushing to the left in FIG. 5 due to the signal pressure supplied to 0c is balanced. When the spool 71 is in the position shown in the lower half of FIG. 5 (when the signal pressure is high), the ports 70a and 70b communicate with each other and the input pulley piston pressure is supplied to the input pulley piston 80. Also,
In the case of the position shown in the upper half of FIG. 5 (when the signal pressure is low), the port 70a and the port 70b are shut off, and the input pulley piston pressure is no longer supplied to the input pulley piston 80.

Therefore, by setting the drain cutoff valve 60 to the position shown in the lower half of FIG. 5 and the input pulley piston oil passage cutoff valve 70 to the position shown in the lower half of FIG.
The hydraulic oil guided to the shift control valve 50 via the line pressure port 50a can be confined in the input pulley piston chamber. As a result, when the shift control valve solenoid 44 is in the non-operating state or the maximum operating state, the shift ratio is gradually increased in response to the leakage of the input pulley piston pressure from the seal, and the shift speed is gradually changed. When a failure occurs in the control valve solenoid 44 or the like, it is possible to prevent a sudden shift. Therefore, unlike the above-described conventional example, there is no sudden increase in engine brake, mechanical deterioration of the engine, or large change in driving force during traveling.

Further, the third embodiment has a solenoid 44
Another valve (drain cutoff valve 60 and input pulley piston oil passage cutoff valve 70) has a function of shutting off the oil passage communicating with the input pulley piston pressure port 50b when the pressure generated is near the maximum value or the minimum value. Since it is performed, the pressure difference of the generated pressure of the solenoid 44 required for switching from the non-shut-off state to the shut-off state can be reduced, so that it can be effectively used for the gear ratio control as shown in FIG. The range of the pressure generated by the solenoid 44 can be made large, and the controllability is improved.

[0021]

As described above, according to the structure of claim 1 of the present invention, in the shift control device of the belt type CVT, the supply / discharge of the hydraulic oil to / from the input pulley piston chamber for controlling the gear ratio is performed electronically. When the electronic control unit is in the non-operating state or the maximum operating state when the transmission control valve that regulates the line pressure and the communication amount with the drain by the signal from the control is used, the port to the input pulley piston chamber Is shut off from the line pressure port and the drain port, and the hydraulic oil is confined in the input pulley piston chamber, so that the input pulley piston pressure may leak from the seal when the electronic control unit is in the non-operating state or the maximum operating state. Depending on the speed change ratio, the gear ratio is changed in a direction that gradually increases, and if a failure occurs in the electronic control unit, etc., it is possible to prevent a sudden change in speed. It can be. Therefore, it is possible to reliably prevent a sudden increase in engine braking, mechanical deterioration of the engine, and a large change in driving force during traveling as in the conventional example described above.

[Brief description of drawings]

FIG. 1 is a first view of a belt type CVT shift control device according to the present invention.
It is a figure which shows the structure of an Example.

FIG. 2 is a diagram for explaining an oil passage cutoff function achieved when the solenoid thrust is near the maximum value and near the minimum value in the first embodiment.

FIG. 3 is a diagram for explaining a relationship between a solenoid thrust (pressure) and a communication amount in the first embodiment and the second embodiment.

FIG. 4 is a second shift control device for a belt type CVT according to the present invention.
It is a figure which shows the structure of an Example.

FIG. 5 is a third shift control device for a belt type CVT according to the present invention.
It is a figure which shows the structure of an Example.

FIG. 6 is a diagram for explaining a relationship between a solenoid pressure and a communication amount in the third embodiment.

[Explanation of symbols]

 40 Shift Control Valve 40a Line Pressure Port 40b Input Pulley Piston Pressure Port 40c Drain Port 40d Signal Pressure Port 40e Notch for Flow Rate Change 41 Spool 41a, 41b, 41c Land 42 Spring 43 Shift Control Valve Solenoid 44 Shift Control Valve Solenoid 45 Solenoid pressure oil passage 60 Drain cutoff valve 70 Input pulley piston Oil passage cutoff valve 80 Input pulley piston

Claims (2)

[Claims] 1. The input / output pulleys each have a piston for applying a force in a direction to narrow the sheave spacing of the pulleys, a line pressure is introduced to the output pulley piston chamber, and an operation to the input pulley piston chamber for gear ratio control is performed. Oil supply / drainage is performed by a shift control valve that regulates the line pressure and the amount of communication with the drain by a signal from an electronic control. In a shift control device of a belt type CVT, the electronic control device is in a non-operating state or a maximum operation. In the state, the port to the input pulley piston chamber is blocked from the line pressure port and the drain port, and the working oil is confined in the input pulley piston chamber. 2. The amount of communication between the port to the input pulley piston chamber and the line pressure port and the drain port is adjusted by one land of the spool, and the front and rear in the spool axial direction with respect to the land. 2. Another land is provided on each of the ends, and each of the other lands is arranged so as to block the line pressure port or the drain port at each end of the range in which the spool is displaced.
A belt type CVT shift control device as described.