JPH0460258A - Hydraulic circuit of continuously variable transmission - Google Patents

Abstract

PURPOSE:To prevent the generation of centrifugal oil pressure by connecting a pressure discharge passage where a pressure retaining valve is disposed to a drain port opened in a backing range position of a manual valve for switching the range pressure. CONSTITUTION:In an R-range position, a drain port 105 of a manual valve 100 is opened, and operating oil in a discharge passage 113 connected to a drin port 127 of a speed change ratio control valve 120 is discharged from the drain port 105 through a branch passage 114. Accordingly, in an advance range position, operating oil in a primary cylinder chamber 42 where the low pressure is retained by a pressure retaining valve 130 is completely eliminated without remaining in the chamber. Accordingly, even if the rotation of an engine is transmitted to a primary shaft through a reversed forward-backward switching mechanism by the connection of a backing brake, no centrifugal oil pressure is generated, and the speed change ration preset as the backing state is kept from being changed.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a hydraulic circuit of a continuously variable transmission, particularly a continuously variable transmission equipped with a pressure holding function in the exhaust pressure passage of the primary cylinder chamber that drives the primary booster. Concerning improvements to the machine's hydraulic circuit.

(Prior Art) An example of a hydraulic circuit for a continuously variable transmission of this type is disclosed in Japanese Patent Application Laid-open No. 127554/1983.

In such a hydraulic circuit, a drain restriction means is provided in the exhaust pressure passage of the primary cylinder chamber, and a low hydraulic oil passage is connected to this exhaust pressure passage. This prevents oil from leaking in the primary cylinder chamber before the start of a shift, and when control pressure is supplied at the start of a shift, the primary pulley is quickly activated.
It is designed to improve the responsiveness of shifting.

(Problem to be Solved by the Invention) However, in the hydraulic circuit of the conventional continuously variable transmission, when driving in the forward range, the shift is started quickly due to the pressure holding function of the primary cylinder chamber, and the shift is started quickly. Perhaps this is intended to improve performance, but in the reverse range, the primary cylinder chamber is set to the lowest hydraulic pressure, and the gear ratio between the primary and secondary pulleys is set to the maximum, which reduces the control hydraulic pressure for gear shifting. No supply will be made.

However, in the reverse range, even though there is no need to consider the shift response to the control oil pressure, low pressure is always applied to the primary cylinder chamber due to the pressure holding function, which means that hydraulic oil remains in the primary cylinder chamber. The state will be as follows.

Therefore, centrifugal force acts on the hydraulic fluid as the primary cylinder chamber rotates, and this becomes centrifugal oil pressure, resulting in a state similar to that in which the oil pressure in the primary cylinder chamber has been increased.

Therefore, the primary pulley driven by the hydraulic pressure in the primary cylinder chamber is driven in a direction in which its groove width becomes narrower, and a constant gear ratio preset for the reverse traveling state is changed, resulting in a driving effect. The ring will deteriorate.

In particular, in the case where the forward/reverse switching mechanism provided on the input side of the primary pulley is configured as a single-binion planetary gear, the gear ratio is usually set to constant speed in the forward state,
The speed is increased in the reverse state, and in such a continuously variable transmission, the disadvantages caused by the centrifugal oil pressure become greater.

In other words, in the reverse state, the increased rotation speed is input to the primary cylinder chamber via the forward/reverse switching mechanism, and the centrifugal oil pressure becomes even larger, resulting in a larger change in the gear ratio. was there.

Therefore, in view of such conventional problems, the present invention provides a hydraulic circuit for a continuously variable transmission that can prevent the generation of centrifugal hydraulic pressure by eliminating the hydraulic oil remaining in the primary cylinder chamber when selecting the reverse range. The purpose is to

(Means for Solving the Problems) In order to achieve the above object, the first configuration of the present invention is to provide a rotary input shaft of a power source, and to actively adjust the groove width by controlling hydraulic pressure supplied to the primary cylinder chamber. between the primary pulley whose groove width is changed, the secondary pulley which is provided on the output shaft of the variable speed rotation and whose groove width is passively changed by the hydraulic pressure supplied to the secondary cylinder chamber, and the primary pulley and the secondary pulley. An endless belt that circulates around the belt and transmits rotational force between both pulleys, and a pressure retaining valve that is provided in the exhaust pressure passage of the primary cylinder chamber and sets and maintains the pressure in the exhaust pressure passage at a low level. In the step-change transmission, the exhaust pressure passage provided with the pressure holding valve is connected to a drain port that is opened at a reverse range position of a manual valve that switches range pressure.

Further, a second configuration of the present invention includes a forward/reverse switching mechanism using a single pinion planetary gear, which speeds up the input rotation of the power source during reversing and transmits it to the rotational input shaft, and a forward/reverse switching mechanism provided on the rotational input shaft. , a primary boob whose groove width is actively changed by the control oil pressure supplied to the primary cylinder chamber, and a groove width which is passively changed by the oil pressure supplied to the secondary cylinder chamber, which is provided on the output shaft of the variable speed rotation. a secondary pulley; an endless belt that is wound around between the primary pulley and the secondary pulley and transmits rotational force between the two pulleys; and an endless belt that is provided in the exhaust pressure passage of the primary cylinder chamber, and In a continuously variable transmission equipped with a pressure holding valve that sets and maintains internal pressure at a low level, the exhaust pressure passage provided with the pressure holding valve is connected to a drain port that is opened at the reverse range position of a manual valve that switches range pressure. The configuration is to connect to

(Function) With the above configuration, in the hydraulic circuit of the continuously variable transmission of the present invention, when the manual valve is switched to the reverse range,
The exhaust pressure passage communicates with a drain port, through which residual hydraulic oil in the primary cylinder chamber can be discharged.

Therefore, in the first configuration of the present invention, even if rotation is transmitted from the power source to the primary cylinder chamber during reverse movement, centrifugal oil pressure is not generated in the primary cylinder chamber, so that the preset reverse movement This can prevent the gear ratio from being changed.

Further, by discharging the remaining hydraulic oil in the primary cylinder chamber in this way, in the second configuration of the present invention, the rotation of the power source is increased in speed in the primary cylinder chamber via the forward/reverse switching device when traveling in reverse. Even if the range of change in the gear ratio becomes particularly large due to transmission, centrifugal oil pressure is not generated in the primary cylinder chamber as in the first configuration, so that the preset gear ratio is prevented from being changed. It can be prevented.

(Example) Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

Fig. 1 and Fig. 2 show an embodiment of the present invention, Fig. 1 shows the main part of the hydraulic circuit of a continuously variable transmission, and Fig. 2 shows the power train of the continuously variable transmission in which this hydraulic circuit is used. The schematic configuration is shown.

The continuously variable transmission shown in FIG. 2 includes a torque converter 2 connected to an output shaft 11 of an engine 1 as a power source, a forward/reverse switching mechanism 3, a continuously variable transmission mechanism 4, a speed reduction mechanism 5,
and a differential mechanism 6.

As is generally known, the torque converter 2 includes a pump impeller 22 that rotates integrally with the converter cover 21 and a turbine launcher that is disposed opposite the pump impeller 22 in a converter cover 21 that is coupled to the output shaft 11. 23, and a stator 24 disposed between the pump impeller 21 and the turbine runner 22.

The engine rotation input to the converter cover 21 is transmitted from the pump impeller 22 to the turbine runner 23 via hydraulic oil as a torque transmission medium sealed in the converter cover 21, and the rotation of the turbine runner 23 is It is taken out via the turbine shaft 25.

Incidentally, the stator 24 performs a torque increasing action according to the relative rotation difference between the pump impeller and the turbine launch 23.

Further, the torque converter 2 is provided with a lock-up piston 26.

The forward/reverse switching mechanism 3 is configured as a single pinion planetary gear, and includes a sun gear 31 and a pinion gear 3 that meshes with the outer circumference of the sun gear 31 and is supported by a carrier 32.
3, and a ring gear 34 that meshes with the outside of this pinion gear 33, and this ring gear 34 is coupled to the turbine shaft 25, and the sun gear 31 is coupled to a primary shaft 41, which will be described later, as a rotational input shaft. be combined.

A forward clutch 36 that can engage and release the ring gear 34 and the carrier 32 is provided, and a reverse brake 37 is provided between the carrier 32 and the transmission case 7.

In the case of the forward range in which the forward clutch 36 is engaged and the reverse brake 37 is released, the ring gear 34
By rotating the and carrier 32 together, the gear ratio of the forward/reverse switching mechanism 3 becomes 1°0.On the other hand, in the case of the reverse range where the forward clutch 36 is released and the reverse brake 37 is engaged, , the rotation of the turbine shaft 25 is reversed and transmitted to the primary shaft 41, and the gear ratio at this time is set to, for example, 0.6, and the speed is increased.

If both the forward clutch 36 and the reverse brake 37 are released, the power will be cut off, and the P range or N
The range will be set.

The continuously variable transmission mechanism 4 includes a primary pulley 43 which is provided on a primary shaft 41 as a rotational input shaft and whose groove width is actively changed by control hydraulic pressure supplied to a primary cylinder chamber 42, and a secondary shaft as an output shaft. A secondary pulley 46 is provided in the primary pulley 44 and whose groove width is passively changed by the hydraulic pressure supplied to the secondary cylinder chamber 45, and a secondary pulley 46 is provided between the primary pulley 43 and the secondary pulley 46. A V-belt 47 serving as an endless belt for transmitting rotational force is provided.

In addition, the primary pulley 43 and the secondary pulley 46
consists of a fixed disk and a movable disk,
The width of each groove is changed by moving the movable disk in the axial direction.

As the groove width of the primary pulley 43 and the secondary pulley 46 increases, the radius of rotation of the V-belt 470 (effective pinch diameter) decreases, and on the other hand, as the groove width decreases, the radius of rotation increases.

Furthermore, the pressure receiving area in the primary cylinder chamber 42 is set approximately twice as large as that in the secondary cylinder chamber 45, and the groove width of the primary pulley 4' is controlled by the control hydraulic pressure supplied to the primary cylinder chamber 42. The hydraulic pressure that is actively changed determines the circumferential radius of the V-belt 47 and is supplied to the secondary cylinder chamber 45.
7. It is used exclusively to maintain a moderate state of tension.

The speed change rotation outputted from the primary shaft 44 is finally decelerated by the reduction mechanism 5, and this final deceleration rotation is distributed to left and right wheels (not shown) by the differential mechanism 6.

In the hydraulic circuit shown in FIG. 1, 100 indicates a manual valve, and this manual valve 100 has each range (P, R,
It has a spool 101 whose movement is switched according to the position of the three land parts 101. a, 101b, 101c
is the clutch pressure introduction port 102. Forward clutch 3
The forward range port 103.6 communicates with the hydraulic chamber of 6. A reverse range port 104 communicating with the hydraulic chamber of the reverse clutch 37 and two drain ports 105 and 106 are communicated and disconnected as appropriate.

That is, the manual valve 100 is in the R (reverse) range position in the illustrated state, the introduction port 102 is in communication with the reverse range port 104, and the reverse clutch 37 is engaged.

At this time, the introduction port 102 is connected to the forward range boat 1.
03 and this forward range port] 03
is communicated with the drain port 105, and the forward clutch 36 is connected to the drain port 105.
will be released.

On the other hand, when the manual valve 100 moves from the R range position to the right in the figure and is set to each of the forward ranges D and 2.1, the introduction port 102 is connected to the forward range port 103.
The forward clutch 36 is engaged, and the drain port 105 is blocked by the land portion 1.0 lb.

At this time, the reverse range port 104 is the introduction port 1.
02 and communicates with the drain port 106, and the reverse brake 37 is released.

By the way, although the primary cylinder chamber 42 and the secondary cylinder chamber 45 are shown in FIG. 1, the line pressure regulated by a line pressure regulating valve (not shown) is introduced into the secondary cylinder chamber 45 via the line pressure passage 110. At the same time, the line pressure from this line pressure passage 110 is introduced into the primary cylinder chamber 42 via the gear ratio control valve 120.

The gear ratio control valve 120 includes a spool 21 and a spring 12 that urges the spool 121 to the upper half position in the figure.
2, a switching chamber 123 formed on the side of the spool 121 opposed to the spring 122, and the spring 1
22 storage chambers 124.

The reverse range pressure of the manual valve 100 is introduced into the storage chamber 124 through the passage 111, and pilot pressure controlled by a duty solenoid valve (not shown) is introduced into the switching chamber 123 through the passage 2. By controlling this pilot pressure, the spool 121 is controlled to move between the upper half position in the figure and the upper half position in the figure.

That is, when the spool 121 is in the lower half position in the figure, the line pressure introduction port 125 and the supply port 126 to the primary cylinder chamber 42 are in wide communication, and
When the spool 121 is in the upper half position in the figure, the introduction port 125 and the supply port 126 are cut off, and the supply port 126 is communicated with the drain port 127.

An exhaust pressure passage 113 is connected to the drain port 127, a pressure retaining valve 130 is provided in the middle of this exhaust pressure passage 113, and the other end of this exhaust pressure passage 113 is connected to a converter relief circuit (not shown). Hydraulic oil discharged from the torque converter is introduced.

That is, the hydraulic oil in the converter relief circuit has a significantly low pressure, and the exhaust pressure passage 113 is filled with this low-pressure hydraulic oil, and the pressure retaining valve 130 is a type of relief valve. This pressure holding valve 130 maintains the pressure within the exhaust pressure passage 113 to an extent that does not affect the speed change control of the primary cylinder chamber 42 .

Therefore, by maintaining a low pressure in the exhaust pressure passage 113, the primary cylinder chamber 42 is always filled with hydraulic oil, and responsiveness at the start of a shift is improved.

Here, in this embodiment, a branch passage 114 is connected in the middle of the exhaust pressure passage 113, and this branch passage 114 is connected to a drain port 105 that is opened at the R range position of the manual valve 100.

With the above configuration, in the hydraulic circuit of the continuously variable transmission of this embodiment, when the manual valve 100 is switched to the R range position, the introduction port 102 is connected to the reverse range port 104.
, the clutch pressure is supplied to the hydraulic chamber of the reverse brake 37, and the transmission ratio control valve 1 is also supplied via the passage 111.
20 spring storage chambers 124 are supplied.

On the other hand, since the pilot pressure introduced into the switching chamber 123 of the gear ratio control valve 120 is set to the lowest pressure in the R range position, the spool 121 of the gear ratio control valve 120 is It is set to the upper half position in the figure by the R range pressure in 124, and the supply port 126 and drain port 127 are communicated.

Therefore, the hydraulic oil in the primary cylinder chamber 42 is discharged from the drain port 127, the primary pulley 43 has the maximum groove width, and the circumferential radius of the V-belt 47 becomes the minimum.
The gear ratio at this time is maximum.

By the way, in the R range position, the drain port 105 of the manual valve]00 is open, and the drain port 105 of the manual valve 00 is opened, and the drain port 105 connected to the drain port 27 of the gear ratio control valve 120 is opened.
The hydraulic oil in 13 is discharged from the drain port 105 via a branch passage 114.

Therefore, the hydraulic fluid in the discharge passage 113, which was maintained at a low pressure by the pressure holding valve 130 in the forward range position, is transferred to the drain port 100 of the manual valve 100 in the R range position.
Therefore, the hydraulic oil is completely removed without remaining in the primary cylinder chamber 42.

Therefore, even if the engine rotation is transmitted to the primary shaft 41 via the forward/reverse switching mechanism 3 which is in the reverse state due to the engagement of the reverse brake 37, no hydraulic oil remains in the primary cylinder chamber 42. There is no generation of centrifugal oil pressure, and the gear ratio preset for the reverse traveling state is prevented from being changed.

In particular, in this embodiment, the forward/reverse switching mechanism 3 is configured with a single pinion planetary gear, and the gear ratio is set to 0.6 and the speed is increased during reverse travel, so hydraulic oil is kept in the primary cylinder chamber 42. If it remains, the centrifugal oil pressure generated by this remaining hydraulic oil will increase in proportion to the square of the rotational speed, and the set speed ratio during reverse movement will change significantly.

However, in this embodiment, even if the speed is increased during reversing, the centrifugal oil pressure is not generated, so reversing is possible with a preset gear ratio, which may worsen the driving feeling. can be prevented.

(Effects of the Invention) As explained above, in the hydraulic circuit of the continuously variable transmission of the present invention, in the first configuration shown in claim 1, a pressure holding valve is provided in the exhaust pressure passage of the primary cylinder chamber. In a continuously variable transmission, this exhaust pressure passage is connected to the drain port of the manual valve that opens in the reverse range position, so when the manual valve is switched to the reverse range, the exhaust pressure passage opens to the drain port and this The remaining hydraulic oil in the primary cylinder chamber can be drained via the drain port.

Therefore, even if rotation is transmitted from the power source to the primary cylinder chamber during reverse movement, centrifugal oil pressure will not be generated within this primary cylinder chamber, so the preset gear ratio during reverse movement will be changed. This can prevent the driving feeling from deteriorating when reversing.

Further, in a second configuration shown in claim 2 of the present invention, in a continuously variable transmission in which the rotation of a power source is transmitted to an input shaft via a forward/reverse switching mechanism using a single pinion planetary gear. Similar to the first configuration, the exhaust pressure passage of the briquette cylinder chamber provided with the pressure holding valve is connected to the drain port that is opened at the reverse range position of the manual valve, so that the forward/reverse switching device is not activated when reversing. Even if the rotation of the power source is transmitted to the primary cylinder cylinder chamber at an increased speed, and even if the change in the gear ratio becomes particularly large, the centrifugal hydraulic pressure in the primary cylinder chamber will not be generated, so the preset gear change will be maintained. This has the excellent effect of preventing the ratio from being changed and preventing the driving feeling from deteriorating when going backwards.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing the main parts of a hydraulic circuit according to an embodiment of the present invention, and FIG. 2 is a schematic diagram showing an embodiment of a power train of a continuously variable transmission to which the present invention is applied. be. 1... Engine (power source) 2... Torque converter 3... Forward/forward switching mechanism 31... Sun gear 32... Carrier 33. ... Binion gear 34 ... Ring gear 4 ... Continuously variable transmission mechanism 41 ... Primary shaft (rotation input shaft) 42 ...
...Primary cylinder chamber 43...Primary pulley 44...Secondary shaft (output shaft) 45...
...Secondary cylinder chamber 46...Secondary pulley 47...V belt (endless belt) 100...
Manual valve 05...Drain port 13...Exhaust pressure passage 14...Branch passage 30...Pressure retention valve

Claims (2)

[Claims] (1) A primary pulley that is installed on the rotational input shaft of the power source and whose groove width is actively changed by the control hydraulic pressure supplied to the primary cylinder chamber, and a primary pulley that is installed on the output shaft of the variable speed rotation and that is supplied to the secondary cylinder chamber. a secondary pulley whose groove width is passively changed by hydraulic pressure; an endless belt that is wound between the primary pulley and the secondary pulley and transmits rotational force between the two pulleys; and exhaust pressure in the primary cylinder chamber. In a continuously variable transmission equipped with a pressure holding valve provided in a passage to set and maintain a low pressure in the exhaust pressure passage, the exhaust pressure passage provided with the pressure holding valve is connected to a manual valve for switching range pressure. A hydraulic circuit for a continuously variable transmission characterized by being connected to a drain port that is opened in a reverse range position. (2) A forward/reverse switching mechanism using a single pinion planetary gear that accelerates the input rotation of the power source during reverse movement and transmits it to the rotational input shaft; and a forward/reverse switching mechanism that is provided on the rotational input shaft and is supplied to the primary cylinder chamber. a primary pulley whose groove width is actively changed by controlled hydraulic pressure; a secondary pulley which is provided on the output shaft of the variable speed rotation and whose groove width is passively changed by the hydraulic pressure supplied to the secondary cylinder chamber; an endless belt that circulates between the secondary pulley and transmits rotational force between the two pulleys; and a belt that is provided in the exhaust pressure passage of the primary cylinder chamber and that sets and maintains the pressure in the exhaust pressure passage at a low level. A continuously variable transmission equipped with a pressure valve, wherein the exhaust pressure passage provided with the pressure holding valve is connected to a drain port that is opened at a reverse range position of a manual valve that switches range pressure. Machine hydraulic circuit.