JP4931364B2 - Control device for continuously variable transmission for vehicle - Google Patents

Description

  The present invention relates to a control device for a continuously variable transmission for a vehicle that changes a gear ratio steplessly according to a running state of the vehicle.

  Various types of shift control of a continuously variable transmission for a vehicle have been conventionally proposed. For example, a target engine speed is set in accordance with an accelerator operation amount so that the actual engine speed matches the target speed. It is known to perform continuously variable transmission control.

By the way, the hydraulic oil of the continuously variable transmission tends to be particularly hot when the engine is at high output, such as when the vehicle is traveling at high speed or traveling on a steep slope. When the temperature of the hydraulic oil rises, problems such as quickening the deterioration of the hydraulic oil, lowering the lubrication performance, and lowering the power transmission procedure occur. Therefore, when the operating time of the engine at a high output exceeds a predetermined time, the gear ratio is changed to a smaller side (high speed side), the high engine speed is lowered, and the heat generation amount is reduced. A continuously variable transmission is disclosed (see, for example, Patent Document 1).
JP-A-61-88065

  By the way, some continuously variable transmissions are provided with an oil cooler for cooling the operating oil that has become hot. In such a continuously variable transmission, the amount of hydraulic oil supplied to each part of the transmission increases when the engine output is high, and the amount of hydraulic oil supplied to the oil cooler decreases. As a result, when the oil temperature of the continuously variable transmission is high and the engine speed is high, such as during high-speed traveling, the transmission is exposed to traveling wind, or measures such as Patent Document 1 are taken, The hydraulic oil that has reached a high temperature can be cooled, such as cooling by an oil cooler.

  However, when the oil temperature of the continuously variable transmission is high and the engine speed is low, such as during low-speed traveling such as uphill traveling, the cooling effect due to traveling wind cannot be expected. If countermeasures are taken, the flow rate of hydraulic oil to the oil cooler becomes insufficient, cooling performance is lowered, and it is difficult to sufficiently reduce the oil temperature of the transmission. At this time, if the hydraulic oil is in a deteriorated state, an abnormal increase in the oil temperature may occur, which may further reduce the performance limit of the continuously variable transmission.

  The present invention has been made in view of such problems, and can control the engine speed in accordance with the deterioration state and operating state of the hydraulic oil to improve the performance of the continuously variable transmission. An object of the present invention is to provide a control device for a continuously variable transmission for a vehicle.

In order to achieve the above object, the present invention provides a control device for a continuously variable transmission for a vehicle (for example, an electric control unit in the present embodiment) that drives the vehicle by changing the output of the engine steplessly and transmitting it to the wheels. ECU), a target engine speed setting means (for example, step S2 in the present embodiment) that sets the target engine speed according to the throttle opening and the vehicle speed of the engine, and the operation of the continuously variable transmission A target for correcting the target engine speed when the deterioration state of the hydraulic fluid is detected by the deterioration state detection means (for example, step S3 in the present embodiment) for detecting the deterioration state of oil and the deterioration state detection means. A rotation speed correction means (for example, step S5 in the present embodiment), and the transmission of the continuously variable transmission is controlled so that the rotation speed of the engine becomes the target rotation speed. It is carried out (for example, step S6 in the present embodiment) as configured. An upper limit value and a lower limit value of the target engine speed at the time of deterioration of the hydraulic oil are set in advance, and the target rotation speed correction means is determined to be in a deteriorated state by the deterioration state detection means. When detected, when the target engine speed exceeds the upper limit value, correction is performed to reset the target engine speed to the upper limit value, and when the target engine speed falls below the lower limit value, Correction is performed to reset the target rotational speed to the lower limit value.

  The control device for a continuously variable transmission for a vehicle according to the present invention includes hydraulic oil temperature detecting means (for example, an oil temperature sensor 38 in the present embodiment) that detects the temperature of hydraulic oil of the continuously variable transmission. The deterioration state detection means detects the deterioration state of the hydraulic oil when the temperature of the hydraulic oil detected by the hydraulic oil temperature detection means exceeds a predetermined oil temperature set in advance according to the vehicle speed. Preferably it is comprised.

The control device for a continuously variable transmission for a vehicle according to the present invention, the target engine upper limit value of the rotational speed and the lower limit at the time of degradation of the hydraulic fluid in advance in accordance with the throttle opening and the vehicle speed of the engine It is preferable that it is set.

  With such a configuration, the control device for a continuously variable transmission for a vehicle according to the present invention controls the number of revolutions of the engine in accordance with the deterioration state and the operating state of the hydraulic oil, thereby improving the performance of the continuously variable transmission. be able to.

  The control device for a continuously variable transmission for a vehicle according to the present invention includes hydraulic oil temperature detecting means for detecting a temperature of hydraulic oil of the continuously variable transmission, and the deterioration state detecting means is the hydraulic oil temperature detecting means. When the temperature of the hydraulic oil detected by the vehicle exceeds a predetermined oil temperature set in advance according to the vehicle speed (which has been subjected to a smoothing process), a deterioration state of the hydraulic oil is detected. Is preferred. This configuration utilizes the fact that the oil temperature of the hydraulic oil at a constant vehicle speed (annealed vehicle speed) settles to a predetermined value when the hydraulic oil has not deteriorated. That is, in the present invention, it is determined that the hydraulic oil has deteriorated when the oil temperature of the hydraulic oil at the smoothed vehicle speed exceeds a predetermined value. With such a configuration, the control device for a continuously variable transmission for a vehicle according to the present invention appropriately controls the engine speed according to the driving state of the vehicle even when the hydraulic oil is deteriorated. It is possible to prevent the temperature of the hydraulic oil from rising abnormally and causing a decrease in the performance limit of the continuously variable transmission. The annealing process is specifically a process of averaging the vehicle speed for a predetermined time by a filter process or the like.

  In the control device for a continuously variable transmission for a vehicle according to the present invention, an upper limit value and a lower limit value of the target engine speed when the hydraulic oil is deteriorated are set in advance according to the throttle opening and the vehicle speed of the engine. And when the target engine speed exceeds the upper limit value when the deterioration state detection means detects that the hydraulic oil is in a deteriorated state, the target speed correction means It is preferable that correction is performed to reset the upper limit value, and when the target engine speed falls below the lower limit value, correction is performed to reset the target speed to the lower limit value. With this configuration, when the temperature of the hydraulic oil in the continuously variable transmission is high and the engine speed is high, the engine speed is lowered to suppress the amount of heat generated, and the temperature of the hydraulic oil in the continuously variable transmission is high. When the engine speed is low, the engine speed is increased to prevent the flow rate to the oil cooler from becoming insufficient, ensuring cooling performance and improving the performance of the continuously variable transmission.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a configuration of a power transmission device having a vehicle continuously variable transmission according to an embodiment of the present invention. As can be seen from FIG. 1, the power transmission device includes an engine E and a continuously variable transmission CVT connected to an output shaft Es of the engine E via a coupling mechanism CP. The continuously variable transmission CVT includes a metal V-belt mechanism 10 disposed between the input shaft 1 and the counter shaft 2, a forward / reverse switching mechanism 20 disposed on the input shaft 1, and a counter shaft 2. A starting clutch (main clutch) 5 disposed above is provided. The continuously variable transmission CVT is used for a vehicle, the input shaft 1 is connected to the engine output shaft via a coupling mechanism CP, and the driving force from the starting clutch 5 is supplied from the differential mechanism 8 to the left and right axle shafts 8a. , 8b to the left and right wheels (not shown).

  The metal V-belt mechanism 10 is wound between a drive-side movable pulley 11 disposed on the input shaft 1, a driven-side movable pulley 16 disposed on the counter shaft 2, and both pulleys 11, 16. And a metal V-belt 15. The drive-side movable pulley 11 includes a fixed pulley half 12 that is rotatably disposed on the input shaft 1, and a movable pulley half 13 that can move relative to the fixed pulley half 12 in the axial direction. A drive-side cylinder chamber 14 is formed on the side of the movable pulley half 13 by being surrounded by a cylinder wall 12a, and pulley control is supplied to the drive-side cylinder chamber 14 from the control valve CV via an oil passage 31. The drive side pressure that moves the movable pulley half 13 in the axial direction is generated by the hydraulic pressure.

  As can be seen from the above configuration, the supply hydraulic pressure (drive and driven side pressure) to both the cylinder chambers 14 and 19 is controlled by the control valve CV, and a side pressure that does not cause the belt 15 to slip is applied. Further, control for making the drive and driven side pressures different is performed, and the wrapping radius of the metal V-belt 15 is changed by changing the pulley groove widths of both pulleys, and control for changing the irregular ratio steplessly is performed.

  The forward / reverse switching mechanism 20 includes a planetary gear mechanism, and includes a sun gear 21 coupled to the input shaft 1, a ring gear 22 coupled to the fixed pulley half 12, a carrier 23 that can be fixed and held by a reverse brake 27, and a sun gear. 21 and a forward clutch 25 capable of connecting the ring gear 22 to the ring gear 22. In this mechanism 20, when the forward clutch 25 is engaged, all the gears 21, 22 and 23 rotate integrally with the input shaft 1, and the drive side pulley 11 is driven in the same direction as the input shaft 1 by driving the engine E ( It is driven to rotate in the forward direction). On the other hand, when the reverse brake 27 is engaged, the carrier 23 is fixedly held, so that the ring gear 22 is driven in the opposite direction to the sun gear 21, and the drive pulley 11 is opposite to the input shaft 1 by the drive of the engine E. It is rotationally driven in the direction (reverse direction).

  The start clutch 5 is a clutch that controls power transmission between the counter shaft 2 and the output side member, that is, the power transmission gears 6a, 6b, 7a, 7b. When this is engaged, power transmission between the two is possible. . Therefore, when the starting clutch 5 is engaged, the engine output changed by the metal V-belt mechanism 10 is transmitted to the differential mechanism 8 via the power transmission gears 6a, 6b, 7a, 7b. Divided and transmitted to the left and right wheels via the left and right axle shafts 8a, 8b. Such engagement control of the starting clutch 5 is performed by clutch control hydraulic pressure supplied from the control valve CV through the oil passage 33.

  In the continuously variable transmission CVT configured as described above, shift control is performed by the drive and driven side pressure supplied from the control valve CV via the oil passages 31 and 32. The starting clutch engagement control is performed by the clutch control oil pressure supplied through the oil passage 33. The operation of the control valve CV is controlled based on a control signal from the electric control unit ECU. For this control, the control valve CV is detected by the throttle opening signal of the engine E detected by the throttle opening sensor 36 and the vehicle speed sensor 37. The vehicle speed signal thus transmitted is sent to the electric control unit ECU.

  Hereinafter, the shift control performed by supplying drive and driven side pressure to the drive and driven cylinder chambers 14 and 19 from the control valve CV, the operation of which is controlled by the electric control unit ECU, via the oil passages 31 and 32 will be described with reference to FIGS. This will be described with reference to FIG.

  As shown in FIG. 2, this shift control is performed by first reading the throttle opening θTH of the engine E detected by the throttle opening sensor 36 and the vehicle speed V detected by the vehicle speed sensor 37 (step S1). The target engine speed Neo corresponding to the current throttle opening θTH and the vehicle speed V detected in step S1 is set from the target engine speed map being set (step S2). Next, deteriorated oil determination processing is performed to determine whether or not the hydraulic oil of the continuously variable transmission CVT is currently in a deteriorated state (step S3).

  In the deteriorated oil determination process S3, as shown in FIG. 3, first, a vehicle speed smoothing process is performed (step S31). Next, a deteriorated oil determination oil temperature threshold D corresponding to the annealed vehicle speed Va is set (step S32). In this setting, a graph indicating the deteriorated oil determination oil temperature threshold D corresponding to the annealing vehicle speed Va is set in advance, and the deterioration oil determination oil temperature threshold D corresponding to the current annealing vehicle speed Va is read from this graph. Done. In the present invention, when the oil temperature T of the hydraulic oil exceeds the deteriorated oil determination oil temperature threshold D, the hydraulic oil of the continuously variable transmission CVT is considered to be in a deteriorated state. Further, the relationship between the annealed vehicle speed Va and the deteriorated oil determination oil temperature threshold value D is set based on a relationship with a predetermined value at which the oil temperature of the non-deteriorated hydraulic oil at a constant vehicle speed is settled.

  Subsequently, the oil temperature T of the hydraulic oil detected by the oil temperature sensor 38 is read (step S33). Then, it is determined whether the vehicle speed V detected by the vehicle speed sensor 37 is equal to or higher than a predetermined high speed and the actual engine speed Nea is equal to or higher than a predetermined high speed, and a predetermined time has elapsed (step S34). Here, when it is not determined that the vehicle speed V is equal to or higher than the predetermined high speed and the actual engine speed Nea is equal to or higher than the predetermined high speed, and the predetermined time has elapsed, the present process is terminated.

  On the other hand, if it is determined in step S34 that the vehicle speed V is equal to or higher than the predetermined high speed and the actual engine speed Nea is equal to or higher than the predetermined high speed, the process proceeds to step S35, and in step S33. It is determined whether or not the temperature T of the hydraulic oil detected by the oil temperature sensor 38 is higher than the value of the deteriorated oil determination oil temperature threshold D corresponding to the current smoothed vehicle speed Va (step S35). Here, when it is determined that the temperature T of the hydraulic oil detected by the oil temperature sensor 38 is higher than the value of the deteriorated oil determination oil temperature threshold D corresponding to the current smoothing vehicle speed Va, the hydraulic oil is deteriorated. It is assumed that the engine is in a state, a deteriorated oil determination flag is set (step S36), and this process is terminated. On the other hand, if it is not determined in step S35 that the temperature T of the hydraulic oil detected by the oil temperature sensor 38 is higher than the value of the deteriorated oil determination oil temperature threshold D corresponding to the current smoothed vehicle speed Va, This process ends.

  Following the deteriorated oil determination process S3 as described above, the process returns to FIG. 2 to determine whether or not the deteriorated oil determination flag is set (step S4). If the deteriorated oil determination flag is not set, the process proceeds to step S6. On the other hand, when the deteriorated oil determination flag is set, that is, when the hydraulic oil is in a deteriorated state, the target engine speed Neo is corrected (step S5).

As shown in FIG. 4, the correction processing S5 for the target engine speed Neo is first performed by limiting the target engine speed Neo corresponding to the current throttle opening θTH and the vehicle speed V (upper limit engine speed Nu, lower limit engine). The rotation speed Nd) is set (step S51). In order to set the limit engine speed (the upper limit engine speed Nu and the lower limit engine speed Nd) of the target engine speed Neo performed in step S51, the throttle opening degree θTH and the vehicle speed V are limited as shown in FIG. A map showing the relationship with the engine speed (upper limit engine speed Nu, lower limit engine speed Nd) is measured and calculated in advance. For example, the lower limit engine speed Nd in the map is based on a base value Nd _base that is preset according to the vehicle speed V, according to the current throttle opening θTH, as shown by Nd _base and Nd _{low TH} in FIG. It is set by multiplying the predetermined correction coefficient. For this reason, in step S51, the engine speed limit (the upper limit engine speed Nu and the lower limit engine speed Nd) corresponding to the current throttle opening θTH and the vehicle speed V is read from the map.

  Then, it is determined whether or not the target engine speed Neo set in step S2 exceeds the upper limit engine speed Nu set in step S51 (step S52). If it is determined that the target engine speed Neo is higher than the upper limit engine speed Nu, correction is performed to reset the target engine speed Neo to the upper limit engine speed Nu (step S53). Exit.

  On the other hand, if it is not determined in step S52 that the target engine speed Neo is higher than the upper limit engine speed Nu, is the target engine speed Neo lower than the lower limit engine speed Nd set in step S51? It is determined whether or not (step S54). Here, when it is determined that the target engine speed Neo is lower than the lower limit engine speed Nd, correction is performed to reset the target engine speed Neo to the lower limit engine speed Nd (step S55).

  On the other hand, if it is not determined in step S54 that the target engine speed Neo is lower than the lower limit engine speed Nd, the target engine speed Neo is the limited engine speed (the upper limit engine speed Nu or the lower limit engine speed Nu). Nd), the correction is not performed and the process is terminated.

  As described above, after the target engine speed Neo is corrected to the limited engine speed (upper limit engine speed Nu, lower limit engine speed Nd) when the hydraulic oil is in a deteriorated state, the correction is performed. Referring back to FIG. 2, control is performed to continuously change the speed ratio of the continuously variable transmission CVT so that the actual engine speed Nea matches the target engine speed Neo (step S6).

  In addition, this invention is not limited to the said embodiment, If it is a range which does not deviate from the summary of this invention, it can improve suitably.

It is the schematic which shows the structure of the power transmission device which has the continuously variable transmission for vehicles which concerns on this invention. It is a flowchart which shows the shift control content in this continuously variable transmission for vehicles. It is a flowchart which shows the control content in the deterioration oil determination process in FIG.2 S3. It is a flowchart which shows the correction | amendment control content of the target engine speed Neo in step S5 of FIG. 4 is a graph showing engine speed limit (upper limit engine speed Nu and lower limit engine speed Nd) set in correspondence with vehicle speed V and throttle opening θTH.

Explanation of symbols

E Engine CVT Continuously variable transmission for vehicle ECU Electric control unit (control device)
36 Throttle opening sensor 37 Vehicle speed sensor 38 Oil temperature sensor

Claims (3)

A control device for a continuously variable transmission for a vehicle that drives a vehicle by changing the output of an engine steplessly and transmitting it to wheels,
Target speed setting means for setting the target engine speed in accordance with the throttle opening of the engine and the vehicle speed;
A deterioration state detection means for detecting a deterioration state of hydraulic oil of the continuously variable transmission;
When the deterioration state of the hydraulic oil is detected by the deterioration state detection means, the target rotation speed correction means for correcting the target engine speed,
Shift control of the continuously variable transmission is performed so that the engine speed becomes the target speed,
An upper limit value and a lower limit value of the target engine speed at the time of deterioration of the hydraulic oil are set in advance,
When the target rotational speed correction means detects that the hydraulic oil is in a deteriorated state by the deterioration state detection means,
When the target engine speed exceeds the upper limit, a correction is made to reset the target speed to the upper limit,
A control device for a continuously variable transmission for a vehicle, wherein when the target engine speed falls below the lower limit value, correction is performed to reset the target speed to the lower limit value. Hydraulic oil temperature detecting means for detecting the temperature of the hydraulic oil of the continuously variable transmission,
The deterioration state detection means detects the deterioration state of the hydraulic oil when the temperature of the hydraulic oil detected by the hydraulic oil temperature detection means exceeds a predetermined oil temperature set in advance according to the vehicle speed. The control device for a continuously variable transmission for a vehicle according to claim 1. According to claim 1 or 2, characterized in that the target engine upper limit value of the rotational speed and the lower limit at the time of deterioration of the working oil is set in advance in accordance with the throttle opening and the vehicle speed of the engine Control device for continuously variable transmission for vehicles.

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