JPH0765662B2 - Hydraulic control device for vehicle belt type continuously variable transmission - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an improvement of a hydraulic control device for a belt type continuously variable transmission for a vehicle.

BACKGROUND ART A pair of primary side variable pulley and secondary side variable pulley provided on a primary side rotating shaft and a secondary side rotating shaft, respectively, and a transmission belt that is wound around the pair of variable pulleys and transmits power, A belt type continuously variable transmission for a vehicle is known that includes a pair of primary side hydraulic cylinders and a pair of secondary side hydraulic cylinders that respectively change the effective diameters of a pair of variable pulleys.

As a hydraulic control device for such a vehicle belt type continuously variable transmission, (a) a first pressure regulating valve for regulating the hydraulic pressure in the first line oil passage to which the hydraulic oil is supplied to the first line hydraulic pressure; (B) The working oil in the first line oil passage is supplied to one of the primary side hydraulic cylinder and the secondary side hydraulic cylinder, and at the same time, the working oil in the other side hydraulic cylinder is caused to flow out to the second line oil passage. Thus, the effective diameters of the primary side variable pulley and the secondary side variable pulley are changed to change the speed ratio of the continuously variable transmission, and the flow cross section of the hydraulic oil is changed to change the speed ratio. A shift control valve for adjusting speed, and (c) a second pressure regulating valve for regulating the hydraulic pressure in the second line hydraulic passage to a second line hydraulic pressure lower than the first line hydraulic pressure, the first line Achieve a target speed ratio with hydraulic pressure The variable pulley of the driving side is generated and pressure is adjusted to a necessary and sufficient value without power loss, while the second line hydraulic pressure is adjusted to a necessary and sufficient value without slippage of the transmission belt. Something like this is considered. For example, the apparatus described in Japanese Patent Application No. 61-37571 previously filed by the applicant of the present application is one example.

Problems to be Solved by the Invention By the way, in such a hydraulic control device, the speed ratio e
In the case of rapidly changing (rotational speed N _{out of the} secondary side rotating shaft / rotational speed N _in of the primary side rotating shaft), the thrust difference between the primary side hydraulic cylinder and the secondary side hydraulic cylinder, that is, When the pressure receiving areas of both hydraulic cylinders are the same, the hydraulic pressure difference between the two line hydraulic pressures is increased and the flow cross-sectional area of the shift control valve is increased to allow a large amount of hydraulic oil to flow. However, it is not preferable to further increase the first line hydraulic pressure on the high pressure side in order to increase the hydraulic pressure difference between the two line hydraulic pressures, because it increases power loss and lowers the durability of the transmission belt. As for the second line hydraulic pressure, due to the structure of the second pressure regulating valve, for example, the presence of a spring for surely moving the spool even when foreign matter is mixed in the hydraulic oil causes the minimum pressure regulating value to be 2 to, for example. 3k
It was difficult to secure a sufficient hydraulic pressure difference because it was restricted to gf / cm ² or more.

Therefore, the changing speed of the speed ratio e, that is, the shift responsiveness is not always satisfactory. For example, when the vehicle is stopped, generally, the speed ratio e is small in preparation for restarting, that is, the first line oil passage. By supplying hydraulic oil to the secondary hydraulic cylinder, the hydraulic oil in the primary hydraulic cylinder is caused to flow out to the second line oil passage, thereby increasing the effective diameter of the secondary variable pulley to the primary variable pulley. It is necessary to hold the continuously variable transmission in a state where the effective diameter of the vehicle is reduced, but if the vehicle stops before the deceleration gear shift state occurs during sudden stop etc., the driving force will be insufficient when the vehicle restarts. In some cases, there was rattling. Further, when the vehicle is stopped, that is, when the transmission belt is moved to the deceleration speed change side when the variable pulley is not rotating, a much larger hydraulic pressure difference is required than when the variable pulley is rotating.
As described above, since it is difficult to secure a sufficient hydraulic pressure difference between the two line hydraulic pressures, there are many problems in designing a continuously variable transmission in order to change the speed ratio e when the vehicle is stopped in such a hydraulic control device. Is accompanied by.

On the other hand, by opening the working oil flowing out from the primary side hydraulic cylinder through the speed change control valve directly to the atmosphere, a sufficient hydraulic pressure difference between both hydraulic cylinders can be secured without making the first line hydraulic pressure particularly high. There has been considered a hydraulic control device that improves the speed response of the speed ratio e to the deceleration speed side and that can move the transmission belt even when the vehicle is stopped. For example, the apparatus described in Japanese Patent Application No. 61-37572 previously filed by the applicant of the present application is one example.

However, in this case, when the torque is transmitted from the secondary rotary shaft to the primary rotary shaft, such as during engine braking, the hydraulic oil flowing out from the primary hydraulic cylinder is always released to the atmosphere. Therefore, it becomes impossible to control the belt clamping pressure by the second pressure regulating valve. For this reason, the first line hydraulic pressure is applied to the primary side hydraulic cylinder by the flow rate control of the shift control valve to secure the belt clamping pressure of the primary side variable pulley. Since there are many error factors in the pressure control, it is necessary to set the first line hydraulic pressure in consideration of a large margin hydraulic pressure in order to reliably prevent slippage of the transmission belt, and the control of the first line hydraulic pressure becomes complicated. It will end up.

Means for Solving Problems The present invention has been made against the above circumstances.
The gist of this is that (a) the first pressure regulating valve,
In a hydraulic control device for a vehicle belt type continuously variable transmission having (b) a shift control valve and (c) a second pressure regulating valve, at least one of the primary side hydraulic cylinder and the secondary side hydraulic cylinder is the other side. When the hydraulic cross-section of the hydraulic cylinder is set to a hydraulic cylinder, the hydraulic oil flowing from the hydraulic cylinder through the speed change control valve is opened when the flow cross-sectional area of the hydraulic oil is larger than a predetermined area, and the hydraulic oil is directly supplied to the drain oil passage. This is because the shift control valve was provided with a drain port for letting it flow out.

Action and Effect of the Invention In such a hydraulic control device, in the case where the flow cross-sectional area of the working oil flowing out through the shift control valve is smaller than a predetermined area, that is, the steady state or the quasi-steady state in which the change in the speed ratio is small In the case of, the drain port of the shift control valve is not opened. Therefore, the hydraulic oil in the hydraulic cylinder on the other side is caused to flow out to the second line oil passage through the speed change control valve, which is necessary for obtaining a suitable belt clamping pressure by which the transmission belt does not slip due to the second pressure regulating valve. A sufficient second line hydraulic pressure is adjusted.

On the other hand, if the flow cross-sectional area of the shift control valve is made larger than a predetermined area in order to change the speed ratio,
The hydraulic oil flowing out from at least one of the primary side hydraulic cylinder and the secondary side hydraulic cylinder through the shift control valve directly flows out from the drain port to the drain oil passage and is released to the atmosphere. Therefore, the hydraulic pressure of the hydraulic cylinder on the other side from which the hydraulic oil flows out is almost equal to the atmospheric pressure, and the first hydraulic pressure on the high pressure side is the same.
A large hydraulic pressure difference can be obtained between the hydraulic cylinder and one hydraulic cylinder to which the hydraulic oil is supplied.

As described above, according to the hydraulic control device of the present invention, it is possible to sufficiently secure the hydraulic pressure difference between the two hydraulic cylinders when changing the speed ratio without impairing the control accuracy of the belt clamping pressure. Thus, the speed ratio of the continuously variable transmission can be rapidly changed, or the speed ratio can be changed when the variable pulley is not rotating, that is, when the vehicle is stopped. Therefore, for example, if the hydraulic oil that flows out from the primary side hydraulic cylinder through the shift control valve is made to flow out into the drain oil passage, the speed ratio of the continuously variable transmission will be reduced even when the vehicle is suddenly stopped. It is changed to the speed change side, and it is easy for the vehicle to restart.

Here, it is only necessary to change the speed ratio of the continuously variable transmission abruptly or to change the speed ratio when the vehicle is stopped only when the speed ratio is changed to the deceleration shift side. Therefore, the drain port is preferably configured to allow only the hydraulic oil in the primary hydraulic cylinder to flow out to the drain oil passage.

The shift control valve may include, for example, a pair of first output port and a first drain port that communicate with the primary hydraulic cylinder, a second output port that communicates with the secondary hydraulic cylinder, and the first line oil passage. And a pair of first discharge port and second discharge port that communicate with the second line oil passage and a second drain port that communicates with the drain oil passage, and a slide on the cylinder bore A spool valve element that is fitted so that the spool valve element and an electromagnetic actuator that moves the spool valve element in the uniaxial direction are provided, and as the spool valve element is moved in the uniaxial direction from its neutral position, the first output port And increasing the flow cross-sectional area between one of the second output port and the input port, while simultaneously increasing the cross-sectional area of the first output port and the second output port. And the other of the first discharge port and the second discharge port is increased, and the flow cross-sectional area between the first output port and the first discharge port is the predetermined area. When the spool valve element is moved so as to be larger than the above, the first drain port and the second drain port are configured to communicate with each other.

Embodiment Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a belt type continuously variable transmission 10 and a hydraulic control device 12 thereof provided in a vehicle. The output of an engine (not shown) of the belt type continuously variable transmission 10 is transmitted through a clutch (not shown). The output from the secondary rotary shaft 18 of the belt type continuously variable transmission 10 transmitted to the primary rotary shaft 16 is transmitted to the drive wheels of the vehicle through an unillustrated auxiliary transmission, differential gear device and the like. It is supposed to be.

The belt type continuously variable transmission 10 includes a primary side rotating shaft 16 and a secondary side rotating shaft 18, and a primary side variable pulley attached to the primary side rotating shaft 16 and the secondary side rotating shaft 18 and having an effective diameter. 20 and the secondary variable pulley 22, the transmission belt 24 wound around the primary variable pulley 20 and the secondary variable pulley 22 to transmit power, and the primary variable pulley 20 and the secondary variable pulley 22. A primary hydraulic cylinder 26 and a secondary hydraulic cylinder 28 that change the effective diameter are provided. These primary hydraulic cylinder 26 and secondary hydraulic cylinder 28
Are formed so as to have the same pressure receiving area, and the primary side variable pulley 20 and the secondary side variable pulley 22 have the same outer diameter, and the belt type continuously variable transmission 10 is small.
The primary variable pulley 20 and the secondary variable pulley 22 are composed of fixed rotating bodies 30 and 32 fixed to the primary rotating shaft 16 and the secondary rotating shaft 18, respectively, and the primary rotating shaft 16 and the secondary rotating shaft 18. The fixed rotary body 30 and the fixed rotary body 30 are provided on the secondary rotary shaft 18 such that they cannot rotate relative to each other and are movable in the axial direction.
And movable rotary bodies 34 and 36 that form a V-shaped groove between the movable rotary bodies 34 and 36.

The hydraulic control device 12 for operating the belt type continuously variable transmission 10 configured as described above is configured as described below. That is, an oil tank is passed through a return path (not shown).
The hydraulic oil that has flowed back to the 38 is sucked by the oil pump 42 via the strainer 40 and the suction oil passage 41, and is pumped to the input port 46 of the speed change control valve 44 and the first line oil passage 50 connected to the first pressure regulating valve 48. To be done. The oil pump 42 constitutes the hydraulic pressure source of this embodiment and is driven by an engine (not shown). The first pressure regulating valve 48 regulates the oil pressure in the first line oil passage 50 to the first line oil pressure Pl ₁ by causing a part of the hydraulic oil in the first line oil passage 50 to flow out to the second line oil passage 52. Press. The second line oil passage 52 is the first discharge port 54 of the shift control valve 44.
And the second discharge port 56 and the second pressure regulating valve 58, respectively. The second pressure regulating valve 58 is provided in the second line oil passage 52.
By letting a part of the hydraulic oil inside flow out to the drain oil passage 60, the oil pressure inside the second line oil passage 52 is adjusted to the second line oil pressure Pl ₂ which is relatively lower than the first line oil pressure Pl _1. Press. The first pressure regulating valve 48 and the second pressure regulating valve 58 are so-called electromagnetic proportional relief valves.

The shift control valve 44 is a so-called proportional control solenoid valve,
A cylinder body 64 in which a cylinder bore 62 is formed, and a cylinder body 62 slidably fitted in the cylinder bore 62
A spool valve element 66, and a pair of first and second springs 68 and 70 for holding the spool valve element 66 in the neutral position by urging the spool valve element 66 from both ends toward the neutral position. , The spool valve element 66 is provided at both ends of the spool valve element 66, and the spool valve element 66 is connected to the second spring.
70 and a first electromagnetic solenoid 72 and a second electromagnetic solenoid 74 that move against the biasing force of the first spring 68. In the cylinder body 64, the input port 4
6, the first discharge port 54 and the second discharge port 56, the first connected to the primary side hydraulic cylinder 26 via the connection oil passage 76
Output port 78 and first drain port 80, second output port 84 connected to the secondary side hydraulic cylinder 28 via connection oil passage 82, second drain port 8 connected to drain oil passage 86
8 are formed so as to communicate with each other through the cylinder bores 62. In addition, the spool valve 66,
With the spool valve element 66 in the neutral position, the land 9 is located at a position corresponding to the second drain port 88, the first discharge port 54, the input port 46 and the second discharge port 56, respectively.
While 0,92,94,96 are formed, the first discharge port 54,
The input port 46 and the second discharge port 56 are the cylinder bore 62.
The annular grooves 98, 100 and 102 are formed at the positions open to the inner peripheral surface of the. These annular grooves 98, 100 and 102 are throttles that continuously change the flow cross-sectional area of the working oil between the lands 92, 94 and 96, respectively, as the spool valve element 66 is moved in the uniaxial direction. Is formed.

As a result, when the spool valve element 66 is in the neutral position, the first output port 78 and the second output port 84 are evenly communicated with the input port 46 and the discharge ports 54, 56 with a small cross-sectional area. A sufficient amount of hydraulic oil to replenish the leak is supplied to the primary hydraulic cylinder 26 and the secondary hydraulic cylinder 28, and a small amount of hydraulic oil is supplied to the discharge port.
Spilled from 54,56.

However, the spool valve 66 is uniaxial from its neutral position,
For example, the communication between the first output port 78 and the input port 46 is cut off as the first electromagnetic solenoid 72 is moved toward the left side in FIG. The flow cross-sectional area between 78 and the first exhaust port 54 is continuously increased, while the communication between the second output port 84 and the second exhaust port 56 is blocked and the second output port 84 thereof is closed. Since the flow cross-sectional area between the input port 46 and the input port 46 is continuously increased, the working hydraulic pressure output from the first output port 78 to the primary hydraulic cylinder 26 is
It becomes lower than the operating oil pressure output from the second output port 84 to the secondary hydraulic cylinder 28. Therefore, the balance of the thrusts of the primary hydraulic cylinder 26 and the secondary hydraulic cylinder 28 in the belt type continuously variable transmission 10 is lost, and the secondary hydraulic cylinder
While the hydraulic oil flows into 28, the hydraulic oil in the primary hydraulic cylinder 26 flows out, and the speed ratio e of the belt type continuously variable transmission 10 is increased.
(The rotation speed N _out of the secondary side rotation shaft 18 / the rotation speed N _in of the primary side rotation shaft 16) becomes small.

On the contrary, as the spool valve element 66 is moved from the neutral position toward the second electromagnetic solenoid 74, that is, in the right direction in FIG. 1, the spool valve element 66 moves between the first output port 78 and the first discharge port 54. The communication between the first output port 78 and the input port 46 is continuously increased, while the communication between the second output port 84 and the input port 46 is blocked. And its second output port 84
Since the flow cross-sectional area between the second discharge port 56 and the second discharge port 56 is continuously increased, the working hydraulic pressure output from the first output port 78 to the primary hydraulic cylinder 26 is the secondary hydraulic pressure output from the second output port 84. It becomes higher than the operating oil pressure output to the cylinder 28. Therefore, the thrust of the primary side hydraulic cylinder 26 and the secondary side hydraulic cylinder 28 in the belt type continuously variable transmission 10 is unbalanced, and hydraulic oil flows into the primary side hydraulic cylinder 26, while the secondary side hydraulic cylinder 28 The hydraulic oil therein flows out, and the speed ratio e of the belt type continuously variable transmission 10 increases.

As described above, the shift control valve 44 has a switching valve function for supplying high-pressure hydraulic oil to one of the hydraulic cylinders 26 and 28 and a low-pressure hydraulic oil for the other, and continuously adjusts the flow rate of the hydraulic oil. It also has a flow rate control valve function, and when the amount of movement from the neutral position of the spool valve element 66 is small, the hydraulic balance of both hydraulic cylinders 26, 28 is controlled to maintain the target speed ratio e. On the other hand, when the amount of movement from the neutral position of the spool valve element 66 is large, the flow rate of the hydraulic oil is increased and the speed ratio e is quickly changed. In other words, when the movement amount of the spool valve 66 is small, the steady state in which the change in the speed ratio e is small is in a difficult or quasi-steady state, and when the movement amount of the spool valve 66 is large, the change in the speed ratio e is large. Is in a large gear shift state.

Here, the land 90 provided on the spool valve 66 is
When the spool valve element 66 is held at or near the neutral position or is moved in the direction to increase the speed ratio e, the second drain port 88 is closed to disconnect the communication with the first drain port 80. However, when the spool valve element 66 is largely moved in the direction to reduce the speed ratio e, that is, to the left in FIG. 1, the second drain port 88 is opened to allow communication with the first drain port 80. At this time, the flow cross-sectional area between the first output port 78 and the first discharge port 54 is large, but the second line oil pressure Pl ₂ in the second line oil passage 52 connected to the first discharge port 54 is , The hydraulic pressure in the primary side hydraulic cylinder 26 is higher than the atmospheric pressure due to the influence of the springs present in the second pressure regulating valve 58.
It is drained to the drain oil passage 86 through 0,88. The flow cross-sectional area between the first output port 78 and the first discharge port 54 at this time is a predetermined area as the timing for opening the drain ports 80 and 88. FIG. 2 is a diagram showing the shift control valve 44 in this state, and FIG. 3 is a diagram showing output hydraulic pressure characteristics of the shift control valve 44. In addition, in FIG.
P _in and P _out are hydraulic pressures in the primary hydraulic cylinder 26 and the secondary hydraulic cylinder 28, respectively.

Further, in the belt type continuously variable transmission 10 and an engine (not shown), etc., the rotational speed N _in of the primary rotary shaft 16, the rotational speed N _out of the secondary rotary shaft 18, and the throttle valve opening indicating the required output of the vehicle. Various sensors for detecting the degree θ _th and the engine rotation speed N _e and supplying signals representing them to a controller (not shown) are provided, and the controller is also used for braking operation. In this case, the brake signal is supplied.

The controller is a so-called microcomputer including a CPU, RAM, ROM, etc., uses the primary storage function of the RAM, processes the input signal described above in accordance with a program previously stored in the ROM, and outputs the first line hydraulic pressure Pl ₁ , 2nd line hydraulic pressure Pl
₂ and a drive signal for controlling the speed ratio e are transmitted to the first pressure regulating valve 48, the second pressure regulating valve 58, the first electromagnetic solenoid 72, and the second pressure regulating valve 58.
Output to each electromagnetic solenoid 74.

The operation of this embodiment will be described below with reference to the flowchart of FIG.

First, by executing step S1, the rotational speed N _in of the primary rotary shaft 16, the rotational speed N _out of the secondary rotary shaft 18, the throttle valve opening θ _th , and the engine rotational speed N _e are read. . Next, in step S2, the speed ratio e is calculated from the rotational speeds N _in and N _out, and _in step S3, the target rotational speed N _in ^* is calculated from the relationship stored in the ROM based on the throttle valve opening θ _th. The target speed ratio e ^{* is} determined from the target speed N _in ^* and the actual speed N _out ^.
Is calculated. The relationship for determining the target rotation speed N _in ^* is, for example, as shown in FIG. 5, and is obtained in advance so that the engine operates exclusively on the minimum fuel consumption rate curve shown in FIG. is there.

In the following step S4, the speed ratio control value V ₀ is calculated based on the speed ratio e, the target speed ratio e ^* and the control constant K.
In step S18, which will be described later, when the speed ratio control value V ₀ is positive, the spool valve element 66 is moved to the right to increase the speed ratio e so that the first electromagnetic solenoid 72 is moved.
Drive signal is output to the spool valve if negative
A drive signal is output to the second electromagnetic solenoid 74 so as to move 66 to the left and reduce the speed ratio e. Further, the magnitude of the speed ratio control value V ₀ corresponds to the movement amount of the spool valve element 66.

Then, in step S5, the actual output torque T _e of the engine is determined based on the throttle valve opening θ _th and the engine rotation speed N _e from a well-known relationship stored in advance in the ROM, and in step S6 It is determined whether the actual output torque T _e of the engine is positive, that is, whether the engine is in the positive torque state in which power is being output or the engine braking state. The reason why such a determination is necessary is that the power transmission direction is different between the positive torque state and the engine braking state, so that the hydraulic pressure change characteristic with respect to the speed ratio e of the hydraulic cylinders 26, 28 changes.

If it is determined in step S6 that the output torque T _e is positive, then step S7 is executed to cause the secondary hydraulic cylinder 28 to generate a narrow pressure necessary and sufficient for the transmission belt 24. Hydraulic pressure (target hydraulic pressure) P _out ′
The second line hydraulic pressure control value V ₂ is determined so that That is, first, the optimum thrust (calculated value) W of the secondary hydraulic cylinder 28 is calculated based on the output torque T _e and the speed ratio e.
_out 'is calculated, the thrust W _out', the pressure receiving area A _out of the secondary side hydraulic cylinder 28, calculates the hydraulic pressure (calculated value) P _out 'on the basis of the rotational speed N _out and the centrifugal force correction coefficient C ₂ , The corrected hydraulic pressure ΔP ₂ is calculated based on the speed ratio e, the target speed ratio e ^* , and the output torque T _e . Then, the second line hydraulic pressure Pl ₂ is calculated based on the hydraulic pressure P _out ′ and the corrected hydraulic pressure ΔP ₂ , and the second line hydraulic pressure control value V ₂ is determined so that the hydraulic pressure Pl ₂ is obtained.

In the following step S8, the first line hydraulic control is performed so that the hydraulic pressure (target hydraulic pressure) P _in ′ _{in the} primary hydraulic cylinder 26 for generating the thrust necessary and sufficient to achieve the target speed ratio e ^* is obtained. The value V ₁ is determined. That is,
First, based on the target speed ratio e ^* and the output torque T _e , the thrust ratio γ ₊ (forward thrust of the secondary side hydraulic cylinder 28 W _out /
The thrust force W _in of the primary hydraulic cylinder 26 is calculated, and the thrust force W _in ′ of the primary hydraulic cylinder 26 is obtained from the thrust ratio γ ₊ and the thrust force W _out ′. And thrust W
_in ', pressure receiving area of primary hydraulic cylinder 26 A _in , rotational speed N
Oil pressure (calculated value) P based on _in and centrifugal force correction coefficient C _1
In ′ is calculated, the primary side line hydraulic pressure Pl ₁ is calculated based on the hydraulic pressure P _in ′ and the corrected hydraulic pressure ΔP ₁ , and the first line hydraulic pressure control value V ₁ is obtained so that the calculated hydraulic pressure Pl ₁ is obtained. Is determined. Note that the above correction hydraulic pressure ΔP ₁
Is determined at the equilibrium point between the steady speed ratio deviation and the power loss.

On the other hand, when it is determined in step S6 that the vehicle is in the engine braking state, the belt type continuously variable transmission is used.
Since the power transmission direction in 10 is opposite,
By executing steps S9 and S10 that are similar to S7 and S8, the required hydraulic pressure in the primary side hydraulic cylinder 26 is
'Together with the second line pressure control value V ₂ are determined, the hydraulic P _out needed in the secondary side hydraulic cylinder 28' P _in the first line pressure control value V ₁ is determined from.

In this way, when the second line hydraulic pressure control value V ₂ and the first line hydraulic pressure control value V ₁ are determined, the following step S11 is executed and the deviation between the target speed ratio e ^* and the actual speed ratio e. It is determined whether or not (e ^* -e) is positive, in other words, whether the speed ratio e is in an increasing speed change state in which the speed ratio e changes in the increasing direction or a decelerating speed change state in which the speed ratio e changes in the decreasing direction. The first line hydraulic pressure control value V ₁ and the second line hydraulic pressure control value V ₂ are corrected in step S12 if the gear is in the shift state and in step S13 if the gear is in the deceleration shift state. In these steps S12 and S13, as the absolute value of the deviation | e ^* −e | increases, the first line hydraulic pressure Pl ₁ and the second line hydraulic pressure P1 are increased.
This is to increase the speed ratio change speed of the belt type continuously variable transmission 14 by enlarging the difference from l ₂ . Note that step S13
The second line hydraulic pressure control value V ₂ is not corrected in step S4 when the deviation (ee ^* ) during deceleration shift is large, the shift control valve is set based on the speed ratio control value V ₀ determined in step S4. This is because the spool valve element 66 of 44 is largely moved to the left, and the hydraulic fluid of the primary hydraulic cylinder 26 is directly discharged to the drain oil passage 86. Also, K ₁ , K ₂ , and K ₃ in steps S12 and S13 are proportional constants.

Then, in subsequent steps S14, S15, S16, whether or not the throttle valve opening θ _th is 0, whether or not the brake signal is supplied, and the rotational speed of the secondary side rotary shaft 18 are determined.
It is determined whether or not N _out is equal to or less than a predetermined constant value a, and if all of them are YES, that is, when the vehicle is almost stopped, step S17 is executed, and otherwise, Immediately executes step S18. In step S17, the speed ratio control value V ₀ ,
First line hydraulic control value V ₁ and second line hydraulic control value V ₂
Are set to C ₀ , C ₁ and C ₂ , respectively. This is a step for putting the belt-type continuously variable transmission 10 into the decelerating and shifting state in preparation for the re-start of the vehicle, and C ₀ increases the spool valve element 66 of the shift control valve 44 to the left in FIG. Move, first
It is a value for causing the second electromagnetic solenoid 74 to output a drive signal so that the drain port 80 and the second drain port 88 are communicated with each other so that the hydraulic oil in the primary hydraulic cylinder 26 directly flows out to the drain oil passage 86. is there. C ₁ is the hydraulic pressure P in the primary hydraulic cylinder 26 that is communicated with the drain oil passage 86.
_in and, between the oil pressure P _out in the first hydraulic line fluid passage 50 is almost made to act as a secondary hydraulic cylinder 28,
It is a value corresponding to the first line hydraulic pressure Pl ₁ required to give a hydraulic pressure difference that can move the transmission belt 24 to the deceleration speed change side even when the vehicle is stopped, that is, when the variable pulleys 20 and 22 are not rotating, Since the hydraulic pressure P _in in the primary side hydraulic cylinder 26 is substantially atmospheric air, this first line hydraulic pressure Pl ₁ does not need to be particularly high pressure as compared with the hydraulic pressure required in normal traveling. Further, C ₂ corresponds to the second line oil pressure Pl ₂ , but at this time, the working oil flowing out from the speed change control valve 44, that is, the working oil in the primary side hydraulic cylinder 26 is directly drain oil passage.
Since the second line oil pressure Pl ₂ can be any value since it is made to flow out to 86, in the present embodiment, the second pressure regulating valve is used.
This is the value corresponding to the minimum pressure regulation value of 58.

After that, the last step S18 of the series of steps is executed, and it corresponds to the speed ratio control value V ₀ , the first line hydraulic pressure control value V ₁ , and the second line hydraulic pressure control value V ₂ determined in the previous step. The drive signal to perform is output. As a result, the speed ratio e, the first line hydraulic pressure Pl ₁ and the second line hydraulic pressure Pl ₂ are
It is controlled by the shift control valve 44, the first pressure regulating valve 48 and the second pressure regulating valve 58.

In such a hydraulic control device of the present embodiment, in the steady state or the quasi-steady state in which the change in the speed ratio e is small,
Alternatively, in the case of a speed-up shifting state in which the speed ratio e is increased,
First drain port 80 and second drain port of the shift control valve 44
It is closed to 88. Therefore, the hydraulic oil flowing out of the shift control valve 44 is regulated to the second line hydraulic pressure Pl ₂ by the second pressure regulating valve 58, and the belt clamping pressure is controlled appropriately.

However, when the spool valve element 66 of the shift control valve 44 is largely moved to the deceleration gear shift side in order to change the speed ratio e to the deceleration gear shift side, the first drain port 80 and the second drain port 88.
Is opened, and the hydraulic oil in the primary side hydraulic cylinder 26 is directly discharged to the drain oil passage 86. Therefore, the oil pressure P _in of the primary hydraulic cylinder 26 is made to almost coincide with the atmospheric pressure, and the hydraulic pressure P _out of the secondary hydraulic cylinder 28 to which the first line hydraulic pressure Pl ₁ on the high pressure side is applied almost as it is. The difference is increased, and the speed change response of the speed ratio e is improved.

Also, when the vehicle is stopped, the spool valve of the speed control valve 44
66 is largely moved to the deceleration gear shift side as in the case of the sudden deceleration gear shift, the gap between the first drain port 80 and the second drain port 88 is opened, and the first line oil pressure Pl ₁ becomes a relatively high oil pressure. It is regulated. Therefore, the belt type continuously variable transmission
While 10 is immediately brought into the deceleration gear shift state, even if the vehicle suddenly stops and stops before the continuously variable transmission 10 is put into the deceleration gear shift state, the transmission belt 24 keeps both hydraulic cylinders 2
It is moved to the deceleration speed change side based on the hydraulic pressure difference of 6,28, and the rattling when the vehicle restarts is eliminated.

Although one embodiment of the present invention has been described in detail with reference to the drawings, the present invention can be implemented in other modes.

For example, in the above embodiment, the stop of the vehicle is determined based on the throttle valve opening θ _th , the brake signal, and the rotation speed N _out , but the throttle valve opening θ _th and the rotation speed N _out , or Brake signal and rotation speed N
It can also be judged based on _out . In addition, instead of the throttle valve opening θ _th and the rotation speed N _out , an idle signal,
Of course, the vehicle speed or the like may be used.

Further, the first line hydraulic pressure control value C ₁ in the above embodiment is
It is a value that regulates the first line hydraulic pressure Pl ₁ to a hydraulic pressure that can move the transmission belt 24 even when the variable pulleys 20 and 22 are not rotating. However, due to the magnitude of the constant value a in step S16, etc., the vehicle suddenly stops. Even if the belt type continuously variable transmission 10 can be decelerated before the vehicle stops,
It is not always necessary to set the value so that the transmission belt 24 can be moved when the variable pulleys 20 and 22 are not rotating.

Further, in the above-described embodiment, the first drain port 80 and the second drain port 88 are made to communicate with each other not only when the vehicle is stopped but also in the normal speed ratio control.
The timing to open between the drain ports 80 and 88 can be set appropriately, and for example, it should be configured to be opened only when the speed ratio control value V ₀ is C ₀ when the vehicle is stopped. Is also possible.

Although not illustrated one by one, the present invention can be carried out in variously modified and improved modes based on the knowledge of those skilled in the art without departing from the spirit thereof.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a hydraulic control device for a vehicle belt type continuously variable transmission according to an embodiment of the present invention. FIG. 2 is a sectional view showing another state of the shift control valve in FIG. Third
The figure is a diagram showing the output hydraulic pressure characteristic of the shift control valve of FIG. FIG. 4 is a flow chart for explaining the operation of the apparatus shown in FIG. FIG. 5 is a diagram showing the relationship between the target rotational speed of the primary side rotating shaft and the throttle valve opening degree in the apparatus of FIG. FIG. 6 is a diagram showing a minimum fuel consumption rate curve of the engine. 10: Belt type continuously variable transmission 12: Hydraulic control device 16: Primary side rotating shaft, 18: Secondary side rotating shaft 20: Primary side variable pulley 22: Secondary side variable pulley 24: Transmission belt 26: Primary side hydraulic cylinder 28: Secondary hydraulic cylinder 42: Oil pump (hydraulic power source) 44: Shift control valve, 48: First pressure regulating valve 50: First line oil passage, 52: Second line oil passage 58: Second pressure regulating valve, 80 : 1st drain port 86: Drain oil passage, 88: 2nd drain port Pl ₁ : 1st line hydraulic pressure Pl ₂ : 2nd line hydraulic pressure

Claims (3)

[Claims] 1. A pair of primary side variable pulley and secondary side variable pulley respectively provided on a primary side rotating shaft and a secondary side rotating shaft, and a transmission belt which is wound around the pair of variable pulleys to transmit power. And a pair of primary side hydraulic cylinders and a pair of secondary side hydraulic cylinders that change the effective diameters of the pair of variable pulleys, respectively, in a belt type continuously variable transmission for a vehicle, in which hydraulic oil is supplied from a hydraulic source. A first pressure regulating valve for regulating the hydraulic pressure in the one-line oil passage to the first line hydraulic pressure;
The hydraulic oil in the first line oil passage is supplied to one of the primary side hydraulic cylinder and the secondary side hydraulic cylinder, and at the same time the hydraulic oil in the other side hydraulic cylinder is caused to flow out to the second line oil passage. The effective diameters of the primary side variable pulley and the secondary side variable pulley are changed to change the speed ratio of the continuously variable transmission, and the flow cross section of the hydraulic oil is changed to adjust the changing speed of the speed ratio. A hydraulic control device comprising: a shift control valve; and a second pressure regulating valve that regulates the hydraulic pressure in the second line hydraulic passage to a second line hydraulic pressure lower than the first line hydraulic pressure, wherein the primary hydraulic cylinder and When at least one of the secondary side hydraulic cylinders is the other side hydraulic cylinder, the flow cross-sectional area of the working oil flowing out from the hydraulic cylinder through the speed change control valve is larger than a predetermined area. A hydraulic control device for a belt-type continuously variable transmission for a vehicle, comprising: a drain port, which is opened when the brake oil is broken, and through which the hydraulic oil is directly discharged to a drain oil passage. 2. The hydraulic pressure for a vehicle belt type continuously variable transmission according to claim 1, wherein the drain port causes only the hydraulic oil in the primary hydraulic cylinder to flow out to the drain oil passage. Control device. 3. The shift control valve comprises: a pair of first output ports and a first drain port communicating with the primary hydraulic cylinder; a second output port communicating with the secondary hydraulic cylinder; and the first line oil. A cylinder bore having an input port communicating with the passage, a pair of first discharge port and second discharge port communicating with the second line oil passage, and a second drain port communicating with the drain oil passage; A spool valve element that is movably fitted and an electromagnetic actuator that moves the spool valve element in a uniaxial direction. The first output is provided as the spool valve element is moved in the uniaxial direction from its neutral position. A flow cross-sectional area between one of the port and the second output port and the input port is increased, and at the same time, the other of the first output port and the second output port is connected to the first port. A flow cross-sectional area between the other of the discharge port and the second discharge port is increased, and a flow cross-sectional area between the first output port and the first discharge port is larger than the predetermined area. The belt-type continuously variable vehicle according to claim 2, wherein the first drain port and the second drain port are communicated with each other when the spool valve element is moved so that Hydraulic control device for transmission.