JP2001227631A - Hydraulic control device for continuously variable transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve fuel consumption by reducing the consumption of operating oil for lubricating pressure in a hydraulic control device for a continuously variable transmission, and reducing the discharge oil quantity and mechanical loss of an oil pump. SOLUTION: The continuously variable transmission has a primary pulley 15 and a secondary pulley 16 with a belt stretched between them. A primary cylinder 22 provided at the primary pulley 15 is provided with a driving oil chamber 23a and a balancing oil chamber 23b for eliminating centrifugal oil pressure generated in the driving oil chamber 23a. A secondary cylinder 27 provided at the secondary pulley 16 is provided with a driving oil chamber 28a and a balancing oil chamber 28b for eliminating centrifugal oil pressure generated in the driving oil chamber 28a. Operating oil from a cooling path 57 with an oil cooler 56 is supplied to the respective balancing oil chambers 23b, 28b through a balancing oil passage 59 to reduce the quantity of operating oil supplied to a lubricating pressure path 46.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a hydraulic control device for a belt-type continuously variable transmission.

[0002]

2. Description of the Related Art A belt-type continuously variable transmission (CV) for automobiles.
T), a metal pulley provided between the primary pulley having a variable pulley groove width provided on the primary shaft on the driving side and a secondary pulley having a variable pulley groove width provided on the secondary shaft on the driven side, that is, the driven side. In some belts, the pulley diameters of a primary pulley and a secondary pulley are changed by hydraulic pressure to change the rotational speed of a secondary shaft steplessly.

[0003] The shift control of the CVT is performed by controlling the hydraulic pressure to the drive oil chambers of hydraulic cylinders provided on the primary side and the secondary side, respectively. The hydraulic pressure applied to each drive oil chamber is controlled by the engine. Is generated by an oil pump driven by the The line pressure applied to the drive oil chamber of the secondary hydraulic cylinder, that is, the secondary pressure, is adjusted by the secondary valve, and the primary pressure applied to the drive oil chamber of the primary hydraulic cylinder is adjusted by the primary valve using the line pressure as the original pressure. Like that.

When the CVT is operating, the primary pulley and the secondary pulley are rotating at a certain speed ratio, and a centrifugal oil pressure due to rotation acts on the drive oil chamber of each cylinder, and the centrifugal oil pressure is adjusted to each drive oil chamber. In the direction in which a pressing force is applied to the belt. Accordingly, the centrifugal oil pressure applied to the drive oil chamber of the primary pulley acts on the gear ratio in the direction of the high gear speed, and the centrifugal oil pressure applied to the drive oil chamber of the secondary pulley acts on the gear ratio in the low gear step. Become.

Therefore, when it is desired to fix the gear ratio to a low gear, a clamp load is applied to the driving oil chamber on the secondary pulley side so that the gear is not shifted by the centrifugal oil pressure generated in the driving oil chamber on the primary pulley side. You have to make it happen. On the other hand, if it is desired to keep the gear ratio at a high gear, a clamp load must be applied to the drive oil chamber on the primary pulley side so that the gear is not shifted by the centrifugal oil pressure generated in the drive oil chamber on the secondary pulley side. No. For this reason, it is necessary to generate an excessive belt clamping force with respect to the driving torque, which causes not only friction loss of the belt but also mechanical loss of the oil pump.

[0006]

Japanese Patent Application Laid-Open No. Hei 6-257651 discloses a balance oil chamber for balancing a centrifugal oil pressure generated in a drive oil chamber in addition to a drive oil chamber in a cylinder on a secondary pulley side. A disclosed CVT is disclosed.

In addition to the driving oil chamber, a balancing oil chamber is formed not only in the cylinder on the secondary pulley side but also in the cylinder on the primary pulley side, and the centrifugal oil pressure generated in the opposite direction to the centrifugal oil pressure generated by the driving oil chamber is balanced oil. Attempts have been made to generate oil in the chamber, but conventionally, hydraulic oil is supplied to the respective balance oil chambers from a lubricating pressure path.

In the CVT, various devices are driven by using an oil pump driven by an engine as a hydraulic pressure source. In other words, not only the primary pulley and the secondary pulley, but also the switching operation of the forward clutch and the reverse brake provided in the forward / reverse switching mechanism is performed by hydraulic pressure. A pressure valve supplies a clutch pressure whose line pressure is reduced. A clutch pressure is also supplied to a lock-up apply chamber in a torque converter having a lock-up clutch, and a lubricating pressure in which a drain pressure of a secondary valve is adjusted is supplied to a lock-up release chamber. The on / off switching of the lock-up clutch is performed according to the lubricating pressure. The lubricating pressure is supplied to the lubricating portion of the forward / reverse switching mechanism, the lubrication of the belt, and the balance oil chamber, in addition to the lock-up clutch.

For this reason, in the CVT, the speed of the pulley is changed when the speed of the pulley changes, and the volume of the drive oil chamber in the cylinder is reduced in order to prevent the belt from slipping due to a reduction in the belt clamping force. The oil pump capacity is set so that a sufficient amount of oil can be secured against changes, and furthermore, the flow rate of hydraulic oil required for forward / reverse switching control, lock-up control, and lubrication of each part can be secured. There is a need to.

[0010] Therefore, the energy loss of the oil pump in the CVT is caused not only by the sliding resistance of each part but also by the oil supplied to the part which operates sufficiently at a pressure lower than the shift control pressure by the pulley. This is due to the fact that the oil pump is pressurized and supplied up to the pulley shift control pressure including the amount, and the required energy of the oil pump increases.

Therefore, since it is necessary to maintain the hydraulic pressure in order to secure the belt clamping force for preventing the belt slip, the lubricating pressure which always requires the oil amount without the line pressure is required. If the amount of oil is reduced, C
It is considered that the hydraulic energy loss in the VT hydraulic control device can be reduced, and the driving energy of the oil pump can be reduced. For example, when a shift operation is performed by a pulley, hydraulic oil of line pressure is required, but at this time, a switching operation is performed in an oil passage that supplies hydraulic pressure to a forward clutch and a reverse brake to which clutch pressure is supplied. Since it is not performed, almost no oil amount is required, and the required oil amount can be reduced by reducing the oil amount of the lubricating pressure.

An object of the present invention is to reduce the consumption of hydraulic oil at a lubricating pressure and to reduce the amount of oil discharged from an oil pump.

Another object of the present invention is to reduce the mechanical loss of an oil pump and achieve an improvement in fuel efficiency.

[0014]

According to the present invention, there is provided a hydraulic control apparatus for a continuously variable transmission, comprising: a primary pulley having a variable pulley groove width mounted on a primary shaft; A hydraulic oil control device for a continuously variable transmission having a secondary pulley with a variable pulley groove width over which a belt is stretched, wherein a driving oil chamber is provided on the primary pulley and applies a driving oil pressure to the primary pulley; A primary cylinder having a balance oil chamber for applying a centrifugal oil pressure in a direction opposite to a centrifugal oil pressure generated in the chamber to the primary pulley; a drive oil chamber provided on the secondary pulley and applying a drive oil pressure to the secondary pulley; A balance oil chamber for applying centrifugal oil pressure generated in the chamber to centrifugal oil pressure in the opposite direction to the secondary pulley. A cylinder, a cooling passage provided with an oil cooler, and a balance oil passage connecting each of the balance oil chambers, so that hydraulic oil that has passed through the oil cooler is supplied to each of the balance oil chambers. It is characterized by having done.

The hydraulic control device for a continuously variable transmission according to the present invention has a lubricating oil supply passage for supplying the hydraulic oil in the balance oil passage to a lubricating portion of a forward / reverse switching mechanism, and the hydraulic oil passing through the oil cooler. Is supplied to each of the balance oil chambers and the lubricating section.

[0016]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a schematic view showing an example of a drive system of a belt-type continuously variable transmission, that is, a CVT. The rotation of a crankshaft 1 driven by an engine (not shown) is transmitted to and from a torque converter 2 as a starting device. The transmission is transmitted to the continuously variable transmission mechanism 4 via the forward switching mechanism 3.

The torque converter 2 has a lock-up clutch 5, which is connected to a turbine shaft 6. One side of the lock-up clutch 5 is a supply chamber, that is, an apply chamber 7a, and the other side is an open chamber, that is, a release chamber 7b, and the hydraulic pressure supplied to the release chamber 7b is circulated through the apply chamber 7a to thereby provide a torque converter. 2 is activated. On the other hand, by supplying hydraulic pressure to the apply chamber 7a and reducing hydraulic pressure in the release chamber 7b, the lock-up clutch 5 is engaged with the front cover 8 to be in a lock-up state. By adjusting the pressure in the release chamber 7b, slip pressure control is performed so that the lock-up clutch 5 is slid.

The forward / reverse switching mechanism 3 includes a forward clutch 11 for transmitting the rotation of the turbine shaft 6 which is an output shaft of the torque converter 2 to the continuously variable transmission mechanism 4 in a forward direction, and a reverse clutch for transmitting the rotation in a reverse direction. And a brake 12 for supplying a hydraulic pressure to the clutch oil chamber 11a to
Is connected, the rotation of the turbine shaft 6 is transmitted to the continuously variable transmission mechanism 4 in the forward direction. When the reverse brake 12 is connected by supplying hydraulic pressure to the brake oil chamber 12a and transmitted in the reverse direction, the rotation is transmitted. Is done.

The continuously variable transmission mechanism 4 has an input shaft, ie, a primary shaft 13 connected to the forward / reverse switching mechanism 3, and an output shaft, ie, a secondary shaft 14, which is parallel to the input shaft.
A primary pulley 15 is provided on the primary shaft 13. The primary pulley 15 is slidable in the axial direction by a ball spline or the like on the primary shaft 13 opposed to the fixed pulley 15 a fixed to the primary shaft 13. The pulley has a movable pulley 15b, and the gap between the cone surfaces of the pulley, that is, the pulley groove width is variable. A secondary pulley 16 is provided on the secondary shaft 14, and the secondary pulley 16 slides in the axial direction on the secondary shaft 14 in opposition to the fixed pulley 16a fixed to the secondary shaft 14 like the movable pulley 15b. A movable pulley 16b that is freely mounted, and the groove width of the pulley is variable.

A belt 17 is stretched between the primary pulley 15 and the secondary pulley 16, and by changing the groove width of both pulleys 15, 16, the ratio of the winding diameter to the respective pulleys 15, 16 is changed. Is changed, the rotation of the primary shaft 13 is transmitted to the secondary shaft 14 at a continuously variable speed.

The rotation of the secondary shaft 14 is transmitted to wheels 19a and 19b via a gear train having a reduction gear and a differential device 18. In the case of a front wheel drive vehicle, the wheels 19a and 19b are connected to the front wheels. Becomes
The basic structure of the CVT drive system described above is disclosed in, for example, Japanese Patent Application Laid-Open No. 10-325458.

FIG. 2 is a diagram showing a specific structure of the continuously variable transmission mechanism 4 shown in FIG. 1. In order to change the groove width of the primary pulley 15, the primary shaft 13 has a cylindrical portion and a disk portion. A plunger 21 is fixed, and a primary cylinder 22 slidably contacting the outer peripheral surface of the plunger 21 is fixed to the movable pulley 15b. A driving oil chamber 23 is provided between the plunger 21 and the movable pulley 15b.
a is formed. On the other hand, a balance oil chamber 23b is formed between the cover 24 provided at the opening end of the primary cylinder 22 and the plunger 21.

To change the groove width of the secondary pulley 16, a plunger 26 having a tapered cylindrical portion is fixed to the secondary shaft 14, and a secondary cylinder 27 slidably contacting the outer peripheral surface of the plunger 26. The drive oil chamber 28a is fixed to the movable pulley 16b, and is formed between the plunger 26 and the movable pulley 16b. On the other hand, a balance oil chamber 28b is formed between the plunger 26 and the cover 29 provided at the opening end of the secondary cylinder 27.

Therefore, when hydraulic oil is supplied to the drive oil chamber 23a in the primary cylinder 22 to increase the volume thereof, the movable pulley 15b moves toward the fixed pulley 15a together with the cylinder 22 to reduce the pulley groove width. When the volume is reduced, the width of the pulley groove is increased. Further, the hydraulic oil is supplied into the drive oil chamber 28a in the secondary cylinder 27 to increase the volume thereof. The movable pulley 15b moves to the fixed pulley 16a side together with the cylinder 27 to reduce the pulley groove width and reduce the volume. Then, the pulley groove width is increased.

The drive oil chamber 23 in the primary cylinder 22
The primary shaft 13 is provided with an oil supply port 31a communicating with the drive oil chamber 23a for supplying hydraulic oil to the oil supply port a, and the cover 24 is provided for supplying hydraulic oil to the balance oil chamber 23b.
An oil supply plug 31b is arranged so as to face an opening formed by the plunger 21 and the plunger 21.

On the other hand, in order to supply hydraulic oil into the driving oil chamber 28a in the secondary cylinder 27, the secondary shaft 14
Is formed with an oil supply port 32a communicating with the drive oil chamber 28a, and an oil supply nozzle 32b is arranged in communication with an oil flow path 33 formed in the secondary shaft 14 for supplying hydraulic oil into the balance oil chamber 28b. ing.

Therefore, when the CVT is operating, centrifugal oil pressure is generated in the drive oil chamber 23a by rotation of the primary pulley 15, and the centrifugal oil pressure is
It acts in the direction of pressing the belt 17 against 5b, but a centrifugal oil pressure in the opposite direction to this direction is generated in the balance oil chamber 23b. Similarly, the secondary pulley 1 is provided in the drive oil chamber 28a.
The centrifugal oil pressure is generated by the rotation of 6, and the centrifugal oil pressure in the opposite direction is generated in the balance oil chamber 28b.

FIG. 3 is a circuit diagram showing a hydraulic control device of the CVT. The torque converter 2, forward / reverse switching mechanism 3 and continuously variable transmission mechanism 4 shown in FIG. It operates by hydraulic pressure.

The suction port of the oil pump 34 is an oil pan 3
5 is connected to an oil pan 35 via an oil strainer 36 provided at an oil supply port 3 through a secondary pressure path, that is, a line pressure path 40.
2a and to the secondary pressure port of the secondary valve 42. This secondary valve 42
Accordingly, the secondary pressure supplied to the driving oil chamber 28a is adjusted to a predetermined pressure and is controlled to a value corresponding to the transmission capacity required for the belt 17. That is, when the engine output is large, such as when climbing a hill or suddenly accelerating, the secondary pressure is increased to prevent the belt 17 from slipping, and when the engine output is small, the secondary pressure is reduced, and the loss and transmission efficiency of the oil pump 34 are reduced. Improvement is achieved.

The line pressure passage 40 is connected to the line pressure port of the primary valve 41,
One primary pressure port is connected to the refueling port 31a via the primary pressure path 43. The primary pressure is adjusted by the primary valve 41 to a value corresponding to the target gear ratio, the vehicle speed, and the like, and the groove speed of the primary pulley 15 is changed to control the vehicle speed.

The line pressure passage 40 is connected to a clutch pressure passage 45 via a clutch pressure valve 44, and the forward clutch 11 of the forward / reverse switching mechanism 3 is connected via the clutch pressure passage 45.
, A brake oil chamber 12a for the reverse brake 12, and an apply chamber 7a for the lock-up clutch 5.
Then, hydraulic oil of clutch pressure is supplied. The clutch pressure in the clutch pressure passage 45 is adjusted based on the line pressure as the original pressure.
When the external pilot pressure is supplied to the
Is set to a low pressure, and when the supply of the external pilot pressure is stopped, the pressure is set to a higher pressure than when it was supplied.

A lubrication pressure passage 46 is connected to the drain port of the secondary valve 42 so that hydraulic oil is supplied to the lubrication portion of the forward / reverse switching mechanism 3 and the lubrication portion of the belt 17 through the lubrication pressure passage 46. It has become. The lubricating pressure in the lubricating pressure passage 46 is regulated by the lubricating pressure valve 47 using the drain pressure of the secondary valve 42 as the original pressure.

Apply chamber 7a of lock-up clutch 5
, The release pressure line 52 connected to the release chamber 7b, the brake switching pressure line 53 connected to the brake oil chamber 12a, and the clutch oil chamber 11a.
A switch valve 55 is provided for controlling connection between the clutch switching pressure passage 54 connected to the lubrication pressure passage 46 and the clutch pressure passage 45 described above.

The switch valve 55 has four portions each having a three-port switching valve structure, and as shown in FIG. 3, the F & R mode in a state where no external pilot pressure is applied, that is, the vehicle speed becomes lower than a predetermined value. The lock-up clutch 5 operates in two positions: an open position of the lock-up clutch 5 in the state, and an engagement position of the lock-up clutch 5 in a state in which the external pilot pressure is applied.

FIG. 4A is a sectional view showing the details of the switch valve 55 when the lock-up clutch 5 is in the open position, and FIG. 4B is a sectional view showing the details of the switch valve 55 when the lock-up clutch 5 is in the engaged position. FIG.

3 and 4 in the open position.
As shown in (A), the lubrication pressure passage 46 and the release pressure passage 52
Are connected to each other by the switch valve 55, and the cooling passage 57 provided with the oil cooler 56 and the applied pressure passage 51 are connected to each other.

The cooling passage 57 is provided with an ATF filter 60 and is connected to a balance oil passage 59. The balance oil passage 59 is connected to a balance oil chamber 23b formed in the primary cylinder 22 of the primary pulley 15,
The secondary pulley 16 is connected to a balance oil chamber 28b formed in the secondary cylinder 27.

Accordingly, when the switch valve 55 is in the open position, the hydraulic circuit operates the torque converter 2 and enters a mode in which the hydraulic control of the forward / reverse switching mechanism 3 can be performed, that is, the F & R mode. The hydraulic oil is supplied to the release chamber 7b, discharged from the apply chamber 7a and passed through the oil cooler 56, and then supplied to the respective balance oil chambers 23b and 28b via the balance oil passage 59.

On the other hand, at the engagement position, as shown in FIG. 4B, the clutch pressure line 45 and the apply pressure line 51 are in communication with each other, and the operating oil set to the clutch pressure is supplied to the apply chamber 7a. Supplied to At this time, the slip pressure passage 58 connected to the clutch pressure passage 45 is connected to the release pressure passage 52.
Is communicated to. A slip pressure adjusting valve 61 is provided in the slip pressure passage 58. The slip pressure adjusting valve 61 controls the slip pressure supplied to the slip pressure passage 58 in accordance with the external pilot pressure supplied to the external pilot chamber. , The pressure is controlled to an arbitrary pressure in the range from the same pressure as the clutch pressure to zero pressure. Therefore, when the slip pressure becomes zero, the lock-up clutch 5 is engaged to enter the lock-up mode, and when the slip pressure becomes equal to the clutch pressure, the lock-up clutch 5 is released. By appropriately controlling the slip pressure, slip control of the lock-up clutch 5 for controlling the rotation difference of the lock-up clutch 5 to be constant can be performed. When the switch valve 55 is in the engaged position, the hydraulic oil from the lubricating pressure passage 46 flows through the cooling passage 57 via the switch valve 55 and is cooled, and then the respective balance oil chambers via the balance oil passage 59. 23b, 28b
Supplied to

As described above, the hydraulic oil is always supplied to the oil cooler 56 by the lubricating pressure regardless of the operation state of the switch valve 55.

In order to supply the external pilot pressure to the slip pressure regulating valve 61, a pilot pressure passage 6 is provided between the pilot port of the slip pressure regulating valve 61 and the clutch pressure passage 45.
The pilot pressure passage 62 is provided with a pilot pressure adjusting valve 63 for controlling the pilot pressure. The pilot pressure adjusting valve 63 is connected to a solenoid 63.
Activated by energizing a.

A manual valve 65 and a reverse signal valve 66, which are respectively linked to each other, are connected to a control lever for switching the running mode, that is, a select lever 64 provided in the vehicle interior.
Reference numeral 66 is operated at five positions corresponding to a P (parking) range, an R (reverse) range, an N (neutral) range, a D (drive) range, and a Ds (sports drive) range set by the select lever 64.

A pilot pressure passage 67 for connecting the clutch pressure passage 45 to an external pilot chamber of the switch valve 55 via a reverse signal valve 66 is provided with a three-port solenoid type switching valve 68. When the solenoid 68a of the switching valve 68 is energized, the switch valve 55 is set to the lock-up control position, that is, the position where the lock-up clutch 5 is engaged, and when the energization to the solenoid 68a is turned off, the F & R mode position is set as shown in FIG. . The pilot pressure passage 67 is connected to an external pilot chamber of the clutch pressure valve 44 as shown by a broken line, and when the reverse signal valve 66 is set to any one of the N position, the D position and the Ds position, the clutch pressure valve 67 The clutch pressure is supplied to the external pilot chamber 44, and the clutch pressure is set to a low pressure. On the other hand, when the reverse signal valve 66 is set to the P position and the R position other than those described above, no hydraulic pressure is supplied to the external pilot chamber of the clutch pressure valve 44,
The clutch pressure is set to a higher pressure than described above.

A common switching pressure passage 69 is provided between the switch valve 55 and the manual valve 65. The switching pressure passage 69 communicates with the slip pressure passage 58 when the switch valve 55 is in the F & R mode position. When the switch valve 55 reaches the lock-up control position, it communicates with the clutch pressure passage 45. When the manual valve 65 is set to either the D range or the Ds range by operating the select lever 64, the switching pressure path 69 is in communication with the clutch switching pressure path 54 via the manual valve 65 and is set to the R range. When this is done, the state is brought into communication with the brake switching pressure path 53.

Next, when the required oil supply amount of the hydraulic oil in the balance oil chambers 23b and 28b is obtained, the hydraulic oil is accumulated at the lower portion of the balance oil chamber 23b to the opening of the balance oil chamber 23b when the pulley stops. When the pulley rotates, the hydraulic oil comes into close contact with the inner peripheral surface of the cylindrical portion of the balance oil chamber 23b due to centrifugal force. Originally, when the pulley is stopped, the balance oil chamber 23b does not hold enough hydraulic oil to be filled. Therefore, it is necessary to supply insufficient hydraulic oil to obtain sufficient centrifugal oil pressure.

When the pulley shifts to the high speed side, hydraulic oil is supplied to the drive oil chamber 23a of the primary pulley 15 to increase the capacity of the drive oil chamber 23a, and the capacity of the balance oil chamber 23b is increased. Will decrease. At this time, the capacity of the balance oil chamber 28b of the secondary pulley 16 increases.

On the other hand, when the pulley shifts to the lower gear, the capacity of the balance oil chamber 23b of the primary pulley 15 increases, and the balance oil chamber 28b of the secondary pulley 16 increases.
Will be reduced.

As described above, each time the pulley shifts, the primary pulley 15 and the secondary pulley 16 are moved.
Of the balance oil chambers 23b and 28b change. Here, as described above, a fixed amount of the hydraulic oil supplied to the oil cooler 56 is secured, and therefore the hydraulic oil supplied from the oil cooler 56 always fills the balance oil chambers 23a and 28b with the hydraulic oil. It is possible to keep.

Therefore, the supply of the working oil to the balance oil chambers 23b and 28b required when the pulley operates can be ensured by the supply amount to the oil cooler 56, so that each of the balance oil chambers 23a , 28b can be supplied only by the hydraulic oil supplied to the oil cooler 56, the amount of oil supplied to the entire lubricating pressure path is reduced, the mechanical loss of the oil pump 34 is reduced, and the fuel efficiency is improved. It becomes possible to plan.

The amount of oil supplied to each of the lance oil chambers 23b and 28b can be adjusted by providing an orifice and a throttle in the balance oil passage 59.

FIG. 5 is a circuit diagram showing a hydraulic control apparatus according to another embodiment of the present invention. In FIG. 5, members common to those shown in FIG. 3 are denoted by the same reference numerals. .

In this case, a lubricating oil supply path 70 is connected to the balance oil path 59,
Thus, the working oil that has passed through the oil cooler 56 is supplied to the lubricating portion of the forward / reverse switching mechanism 3.

Normally, a fixed amount of hydraulic oil is supplied to the oil cooler 56, and the balance oil chambers 23b and 23b of the primary pulley 15 and the secondary pulley 16, respectively.
The amount of oil supplied to 28b is set to the required amount of oil in accordance with the change in volume, but the hydraulic oil supplied from oil cooler 56 is constant regardless of the speed change state of the pulley.
When the pulley is not shifting, the balance oil chambers 23b, 28
Since the capacity of b does not change, the hydraulic oil overflows from the balance oil chamber. If there is a large amount of hydraulic oil around the pulley, a resistance to agitation will occur. However, oil cooler 56
The amount of oil supplied to the balance oil chamber is determined by the amount of heat radiation from the transmission, so that generally a larger amount of hydraulic oil is supplied to the balance oil chamber than the required amount of oil supplied to the balance oil chamber. Therefore, of the hydraulic oil that has been supplied from the lubrication pressure path to the forward / reverse switching mechanism 3 for lubrication, the excess of the hydraulic oil that passes through the oil cooler 56, excluding the hydraulic oil that is being supplied to the balance oil chamber, is used. By doing so, it is possible to reduce the required oil amount in the lubricating pressure path and reduce the stirring resistance due to excessive hydraulic oil in the pulley.

The amount of oil supplied to each of the lance oil chambers 23b and 28b and the lubricating portion of the forward / reverse switching mechanism 3 can be adjusted by providing an orifice or a throttle in the balance oil passage 59 or the lubricating oil supply passage 70. .

The present invention is not limited to the above-described embodiment, and it goes without saying that various changes can be made without departing from the spirit of the present invention. For example, the drive system of the belt-type continuously variable transmission is not limited to the case shown in FIG. 1, and the present invention can be applied to various types such as a type having no torque converter 2.

[0057]

According to the present invention, the working oil that has passed through the oil cooler is supplied to the respective balance oil chambers of the primary pulley and the secondary pulley without being supplied directly from the oil pump. The amount of oil supplied to the pressure path can be reduced.

The supply of the hydraulic oil to each of the balance oil chambers is performed in order to supply the required oil amount when the volume of the balance oil chamber changes during the shifting of the primary pulley and the insufficient hydraulic oil amount at the start of rotation to supply the lubricating pressure. This can be performed from the cooling passage without providing a special oil passage.

The supply of the lubricating oil to the lubricating portion of the forward / reverse switching mechanism can be performed from the cooling passage through the lubricating oil supply passage without performing the lubrication oil passage directly supplied from the oil pump.

By reducing the required amount of oil flowing through the lubricating pressure passage, the discharge amount of the oil pump can be reduced, the mechanical loss of the oil pump can be improved, and the fuel efficiency can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating an example of a drive system of a belt-type continuously variable transmission.

FIG. 2 is an enlarged sectional view showing the continuously variable transmission mechanism shown in FIG. 1;

FIG. 3 is a hydraulic circuit diagram showing a hydraulic control device for a continuously variable transmission according to an embodiment of the present invention.

FIGS. 4A and 4B are enlarged sectional views of the switch valve shown in FIG. 3;

FIG. 5 is a hydraulic circuit diagram showing a hydraulic control device for a continuously variable transmission according to another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Crankshaft 2 Torque converter 3 Forward / reverse switching mechanism 4 Continuously variable transmission mechanism 5 Lock-up clutch 6 Turbine shaft 7a Apply chamber 7b Release chamber 11 Forward clutch 12 Reverse brake 13 Primary shaft 14 Secondary shaft 15 Primary pulley 16 Secondary pulley 22 Primary cylinder 23a Drive oil chamber 23b Balance oil chamber 27 Secondary cylinder 28a Drive oil chamber 28b Balance oil chamber 34 Oil pump 40 Line pressure path 41 Primary valve 42 Secondary valve 43 Primary pressure path 44 Clutch pressure valve 45 Clutch pressure path 46 Lubrication pressure path 47 Lubrication pressure valve 55 Switch valve 59 Balance oil path 70 Lubrication oil supply path

Claims (2)

[Claims] 1. A pulley having a variable pulley groove width mounted on a primary shaft and a secondary pulley having a variable pulley groove width mounted on a secondary shaft and having a belt stretched between the primary pulley and the primary pulley. A hydraulic control device for a step transmission, comprising: a drive oil chamber provided on the primary pulley and applying a drive oil pressure to the primary pulley; and a centrifugal oil pressure generated in the drive oil chamber in a direction opposite to a centrifugal oil pressure applied to the primary pulley. A primary cylinder having a balance oil chamber to be added; and a drive oil chamber provided on the secondary pulley and applying a drive oil pressure to the secondary pulley, and a centrifugal oil pressure generated in the drive oil chamber in a direction opposite to a centrifugal oil pressure applied to the secondary pulley. A secondary cylinder having a balance oil chamber to be added, a cooling passage provided with an oil cooler, and And a balance oil passage connecting the balance oil chambers to the respective balance oil chambers. The hydraulic oil passing through the oil cooler is supplied to each of the balance oil chambers. Hydraulic control device. 2. The hydraulic control device for a continuously variable transmission according to claim 1, further comprising a lubricating oil supply passage for supplying hydraulic oil in said balance oil passage to a lubricating portion of a forward / reverse switching mechanism. A hydraulic control device for a continuously variable transmission, wherein the hydraulic oil that has passed is supplied to the respective balance oil chambers and the lubricating unit.