JP6565027B2 - Hydraulic control device for power split type continuously variable transmission - Google Patents

Description

  The present invention relates to a hydraulic control device for a power split type continuously variable transmission, and more particularly to clutch switching control when a running mode is switched in a power split type continuously variable transmission.

  Generally, a power split type continuously variable transmission including a continuously variable transmission and a sub-transmission is provided. This power split type continuously variable transmission includes a continuously variable transmission and an auxiliary transmission capable of increasing the gear ratio to a higher gear ratio than the continuously variable transmission in order to expand the transmission range of the transmission. The sub-transmission is provided for assisting the shifting of the continuously variable transmission during high-speed traveling, or the sub-transmission and the sub-transmission By running in split mode, which is driven in combination with a continuously variable transmission, fuel efficiency is improved at high speeds.

  Switching between the continuously variable transmission mode and the split mode is performed by switching (switching) the continuously variable transmission mode clutch (or brake) and the split mode clutch (or brake). The switching control of both clutches is performed by changing the clutch that supplies the hydraulic oil, and the kinematic viscosity of the hydraulic oil changes depending on the oil temperature. For this reason, the friction coefficient of both clutches changes, making it difficult to switch between both clutches stably. As a result, the switching time varies, giving the user a sense of incongruity such as shock or engine run-up. .

  Actually, for example, even in an infinite transmission (a continuously variable transmission) that is disclosed in Patent Document 1 and includes a sub-transmission in a continuously variable transmission, the transmission efficiency in the output state near the maximum speed ratio is improved. Although the vehicle running fuel efficiency is improved, the problem of the change in the oil temperature of the hydraulic oil at the time of switching between the continuously variable transmission mode clutch and the split mode clutch remains.

Japanese Patent No. 4552376

  The present invention has been created in view of the above problems, and includes a continuously variable transmission mode in which only the continuously variable transmission is driven, and a split mode in which the auxiliary transmission and the continuously variable transmission are driven in combination. An object of the present invention is to provide a hydraulic control device capable of stably performing switching control between both modes even when the kinematic viscosity changes depending on the temperature of the hydraulic oil in a power split continuously variable transmission capable of traveling.

The present invention travels in a continuously variable transmission mode in which only a continuously variable transmission is driven during normal traveling, and a sub-transmission provided to assist shifting of the continuously variable transmission during high-speed traveling, and / or the sub-transmission. Provided is a hydraulic control device for a power split type continuously variable transmission that travels in a split mode that is driven by using both a transmission and the continuously variable transmission. In this hydraulic control device,
The clutch or brake engaged in the continuously variable transmission mode and the clutch or brake engaged in the split mode are at least a predetermined oil temperature TS1 at which the dynamic viscosity of the hydraulic oil used for engagement control is stabilized. In this case, switching between the continuously variable transmission mode and the split mode is permitted.

Further, switching between the continuously variable transmission mode and the split mode is restricted when the hydraulic oil is at or above a predetermined oil temperature TS2 higher than the predetermined oil temperature TS1 , The switching to the split mode is stopped when the hydraulic oil is lower than the predetermined oil temperature TS1.

  According to the hydraulic control device of the power split type continuously variable transmission of the present invention, the clutch or brake engaged in the continuously variable transmission mode and the operation used for switching control of the clutch or brake engaged in the split mode. Since both clutches and brakes are switched only when the oil kinematic viscosity is stable and above the specified oil temperature, even when the kinematic viscosity changes due to the oil temperature, the switching control of both modes is stable. Can be implemented.

  In addition, since switching between the continuously variable transmission mode and the split mode is restricted when the hydraulic oil is at a predetermined oil temperature or higher, switching control between both modes can be stably performed. As will be described in detail later, it is possible to prevent the occurrence of a shock due to the slip of the endless belt provided in the continuously variable transmission, and to improve the life of the endless belt.

  The predetermined oil temperature at which the switching of both clutches or brakes is permitted is set lower than the predetermined oil temperature at which the switching is restricted.

It is a flow figure showing an outline of a control flow of a hydraulic control device of a power split type continuously variable transmission concerning one embodiment of the present invention. 1 is a skeleton diagram showing an outline of a configuration of a power split continuously variable transmission in which a hydraulic control device according to an embodiment of the present invention is employed. It is a graph which shows the outline of the kinematic viscosity characteristic of the hydraulic fluid used for the power split type continuously variable transmission by which the hydraulic control apparatus which concerns on one Embodiment of this invention is employ | adopted.

<Configuration of power split type continuously variable transmission>
As a premise for explaining the hydraulic control device of the present invention, the configuration of the power split continuously variable transmission is outlined with respect to the configuration of the power split continuously variable transmission. This will be described with reference to FIG.

  The power split type continuously variable transmission 50 includes a continuously variable transmission 10 and an auxiliary transmission 20. The continuously variable transmission 10 is generally composed of a primary pulley 12, a secondary pulley 14, and an endless belt 16 that is stretched between the primary pulley 12 and the secondary pulley 14 to transmit power. The auxiliary transmission 20 is generally composed of a front planetary 22, a split gear 24, and a rear planetary 24.

  When traveling in a continuously variable transmission mode in which only the continuously variable transmission 10 is driven (hereinafter also simply referred to as “CVT mode”), the CVT mode clutch 30 is engaged and power split from an engine (not shown). The driving force input to the continuously variable transmission 50 is shifted and output by the continuously variable transmission 10, and the vehicle (not shown) travels.

  When traveling in the split mode in which the sub-transmission 20 and / or the sub-transmission 20 and the continuously variable transmission 10 are driven in combination, the split mode brake 32 is engaged and the engine is separated from the engine. The driving force input to the stepped transmission 50 is shifted and output using the auxiliary transmission 20 and / or the auxiliary transmission 20 and the continuously variable transmission 10 together, and the vehicle travels.

  During normal driving, where the vehicle starts and accelerates from a stopped state, the CVT mode clutch 30 is engaged and the vehicle travels in the CVT mode, and if the vehicle speed exceeds a predetermined value, the split mode brake 32 is engaged. The CVT mode clutch 30 is released and the vehicle shifts to the split mode.

  At this time, so-called holding control is performed in which the CVT mode clutch 30 in the engaged state is released and the split mode brake 32 in the released state is engaged. In the hydraulic control device of the present invention, when the kinematic viscosity of hydraulic oil (not shown) used for engagement control (holding control) is equal to or higher than a predetermined oil temperature, the continuously variable transmission mode and the split mode Switching control is permitted.

  More specifically, it is a chart showing an outline of kinematic viscosity characteristics of hydraulic oil used in a power split type continuously variable transmission 50 in which a hydraulic control device (not shown) according to an embodiment of the present invention is employed. As shown in FIG. 3, the kinematic viscosity of the hydraulic oil varies greatly depending on the temperature of the hydraulic oil (hereinafter also simply referred to as “oil temperature”). In particular, when the oil temperature is low, the change in kinematic viscosity due to the change in oil temperature is large.

  In the hydraulic control device of the present invention, switching between the CVT mode and the split mode is permitted when the oil temperature of the hydraulic oil is equal to or higher than the predetermined oil temperature TS1.

<< Control Configuration of Hydraulic Control Device of the Present Invention >>
FIG. 3 is a flowchart showing an outline of a control flow of a hydraulic control device of a power split type continuously variable transmission 50 according to an embodiment of the present invention, for mode switching control between both modes in the hydraulic control device of the present invention. This will be described in detail with reference to FIG.

  The mode switching control is started at STEP 110 in the control flow of FIG. 1 (hereinafter simply referred to as “S110”, and the same applies to other STEPs). In S112, it is confirmed that the oil temperature of the hydraulic oil is TS1 or higher. If the confirmation result is satisfied, the process proceeds to S114.

  When the oil temperature of the hydraulic oil is lower than TS1, the dynamic viscosity of the hydraulic oil is not stable, and the dynamic viscosity of the hydraulic oil is not within the range that can be absorbed by hydraulic control, so the mode can be switched stably. Therefore, the mode switching control is stopped.

  In S114 of FIG. 1, it is confirmed that the vehicle speed is equal to or higher than a predetermined value. If the confirmation result is satisfied, the process proceeds to S116. If the vehicle speed is lower than the predetermined value, it is determined that it is more advantageous to continue traveling in the CVT mode in order to improve fuel consumption, and mode switching is stopped.

  In S116 of FIG. 1, it is confirmed that the accelerator opening is equal to or greater than a predetermined value. If the confirmation result is satisfied, the process proceeds to S118. If the accelerator opening is lower than the predetermined value, it is determined that the user (driver) intends to decelerate, and the mode switching control is stopped.

  In S118 of FIG. 1, in response to the results of S112 to S116, mode switching is permitted, switching control between the CVT mode and the split mode is executed, and the switching control is terminated in S120.

  By executing switching control between the CVT mode and the split mode according to the control flow described above, it is possible to achieve stable switching control between both modes.

  Further, in the hydraulic control device of the present invention, switching between the continuously variable transmission mode and the split mode is restricted when the oil temperature of the hydraulic oil is equal to or higher than the predetermined oil temperature TS2. The control flow in this case is almost the same as the case where switching between the continuously variable transmission mode and the split mode is permitted when the oil temperature of the hydraulic oil is equal to or higher than the predetermined oil temperature TS1. Description is omitted.

  The difference is that in the case where switching between the continuously variable transmission mode and the split mode is restricted when the oil temperature of the hydraulic oil is equal to or higher than the predetermined oil temperature TS2, in step 110 of FIG. It is a point that temperature is lower than TS2.

  When the oil temperature of the hydraulic oil is equal to or higher than the predetermined oil temperature TS2, it is possible to stably perform the switching control of both modes by restricting the switching control of both modes, and the continuously variable transmission 20 The occurrence of a shock due to the slip of the endless belt 16 provided can be prevented, and the life of the endless belt 16 can be improved.

  More specifically, when the oil temperature of the hydraulic oil is equal to or higher than a predetermined TS2, the dynamic friction coefficient of the clutch and / or the brake is lowered as the kinematic viscosity is lowered. For this reason, when switching control of both modes is performed, the engagement force does not act smoothly in the clutch and / or the brake, and so-called judder is generated in which abnormal noise or vibration occurs.

  When this judder occurs, vibration is generated, or in the continuously variable transmission 10 shown in FIG. 2, the input to the upper end belt 16 that transmits power between the primary pulley 12 and the secondary pulley 14 becomes excessive. There is a case. For this reason, a belt slip occurs in which the pulley and the endless belt 16 slide relative to each other, the endless belt 16 is damaged and the service life is shortened, or the primary pulley 12 and the secondary pulley 14 are damaged to perform a normal shift. It becomes difficult.

  In the hydraulic control device of the present invention, as described above, when the oil temperature of the hydraulic oil is equal to or higher than the predetermined oil temperature TS2, switching between the continuously variable transmission mode and the split mode is restricted. Therefore, it is possible to prevent the above-described decrease in life due to damage to the endless belt 16 and difficulty in normal gear shifting due to damage to the primary pulley 12 and the secondary pulley 14 as described above.

  In the above description, the case of shifting from the CVT mode to the split mode has been described as an example, but the same applies to the case of shifting from the split mode to the CVT mode. In the above description, the clutch that is engaged in the CVT mode is a clutch and the brake that is engaged in the split mode is a brake. However, this may be changed as appropriate depending on the configuration of the power split continuously variable transmission.

  As an example of means for detecting the oil temperature of the hydraulic oil, an oil temperature sensor (not shown) provided in the power split continuously variable transmission 50 can be considered. The position where the oil temperature sensor is disposed may be in a hydraulic circuit that switches the oil path by control, or may be an oil pan (not shown) in which hydraulic oil is stored, and the position of the oil temperature sensor can be set as appropriate. is there. Moreover, the oil temperature of the hydraulic oil of the power split type continuously variable transmission 50 may be detected by other equipment mounted on the vehicle.

  As described above, the embodiment and concept of the hydraulic control device of the power split type continuously variable transmission according to the present invention have been described, but the present invention is not limited to this, and the claims and the description etc. Those skilled in the art will appreciate that other variations and modifications can be obtained without departing from the spirit and teaching of the description.

DESCRIPTION OF SYMBOLS 10 Continuously variable transmission 12 Primary pulley 14 Secondary pulley 16 Endless belt 20 Subtransmission 22 Front planetary 24 Split gear 26 Rear planetary 30 CVT mode clutch 32 Split mode brake 50 Power split type continuously variable transmission TS1 Mode switching is permitted Predetermined oil temperature TS2 Predetermined oil temperature at which mode switching is regulated

Claims (1)

It travels in a continuously variable transmission mode in which only the continuously variable transmission is driven during normal traveling, and a sub-transmission provided to assist shifting of the continuously variable transmission during high-speed traveling, and / or the sub-transmission and the A hydraulic control device for a power split type continuously variable transmission that travels in a split mode that is driven in combination with a continuously variable transmission,
The clutch or brake engaged in the continuously variable transmission mode and the clutch or brake engaged in the split mode are at least a predetermined oil temperature TS1 at which the dynamic viscosity of the hydraulic oil used for engagement control is stabilized. In this case, switching between the continuously variable transmission mode and the split mode is permitted ,
Switching between the continuously variable transmission mode and the split mode is restricted when the hydraulic oil is equal to or higher than a predetermined oil temperature TS2 higher than the predetermined oil temperature TS1,
Switching between the continuously variable transmission mode and the split mode is stopped when the hydraulic oil is lower than the predetermined oil temperature TS1.
A hydraulic control device for a power split type continuously variable transmission.