JP2010230132A - Control device of vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To inhibit fuel consumption of an engine and belt slip when returning from idling stop in consideration of leakage characteristics of seal rings. <P>SOLUTION: An idling stop vehicle equipped with an engine and a belt type continuously variable transmission includes the resin-based seal rings provided at sliding parts of piston chambers of a primary pulley and a secondary pulley, a time detection means detecting an elapsed time from automatic stop of the engine, an oil temperature detection means detecting temperature of hydraulic oil in the continuously variable transmission, and a restart means forcibly restarting the engine when the elapsed time from the automatic stop of the engine reaches a predetermined time T. The time T at high oil temperature is set longer than the time at low oil temperature, therefore air intrusion into the piston chambers of the pulleys during idling stop can be prevented, and prevention of belt slip when returning from idling stop and reduction of fuel consumption and exhaust gas can be achieved together. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a vehicle control device, and more particularly to a control device in an idle stop vehicle equipped with a belt type continuously variable transmission.

  2. Description of the Related Art Conventionally, there has been known a vehicle that performs an idle stop control that automatically stops an engine when a predetermined condition is satisfied, and suppresses useless fuel consumption and emission of gas while the vehicle is stopped. Engine stop conditions in such idle stop control include vehicle stop and brake ON, and engine restart conditions include brake OFF and accelerator pedal depression.

  2. Description of the Related Art A vehicle equipped with an engine that performs idle stop control as described above and a belt-type continuously variable transmission is known. Generally, a continuously variable transmission is provided with a primary pulley and a secondary pulley over which a belt is laid, and by controlling the oil pressure of these pulleys, a shift control and a belt clamping pressure control are performed.

  In the case of an idle stop vehicle having only an oil pump driven by an engine as a hydraulic pressure source of the pulley, the oil pump is also stopped in the idle stop state, so that no hydraulic pressure is supplied to the pulley. Therefore, when the engine is restarted next, there is a problem that a certain time is required until the oil pump is operated and the power transmission of the continuously variable transmission is resumed, and the start is also swayed.

  When the engine stop time due to the idle stop becomes long, the oil in the piston chamber leaks from the sliding portion of the pulley with the passage of time, and air may be mixed into the piston chamber. When air is mixed, it takes time to fill the piston chamber with hydraulic oil when the engine is restarted. In general, the flow rate of the hydraulic oil in the primary pulley is controlled, but a small-diameter orifice is provided in the supply oil passage for the primary pulley to reduce the flow rate in order to prevent sudden shift when shifting to the closing control when the vehicle is stopped. Sometimes. For this reason, when air is mixed into the piston chamber of the primary pulley, the pressure increase is greatly delayed as compared with the secondary pulley, and the transmission torque decreases transiently, causing belt slippage.

  FIG. 9 shows a conventional control method at the time of idling stop return (engine restart). When an idle stop return request is made at time t10, the engine speed starts to increase at time t11. At time t12, which is slightly delayed from time t11, the hydraulic pressures of the primary pulley and the secondary pulley start to increase, and the belt transmission torque also increases. However, when air enters the piston chamber of the primary pulley, it takes time to fill the piston chamber with hydraulic oil, so that the primary pulley hydraulic pressure does not increase immediately from time t12 as shown by the broken line, causing a delay. As a result, the belt transmission torque decreases as indicated by a broken line, and belt slippage occurs.

  In Patent Document 1, in order to suppress the slack at the time of starting, the limiting means provided in the hydraulic oil discharge path of the continuously variable transmission and the limiting means during the idle stop are operated to control the hydraulic oil of the continuously variable transmission. What provided the control means which restrict | limits discharge | emission is disclosed. Even if the restricting means restricts the discharge of the hydraulic oil, there is a leakage of the hydraulic oil from a sliding portion or the like, and a hydraulic pressure drop due to this leakage occurs. The engine is automatically restarted after a lapse of a predetermined time in consideration of the hydraulic pressure drop due to.

  However, since the decrease in hydraulic pressure of hydraulic oil varies depending on various factors, the time for restarting the engine cannot be determined uniformly. For example, a sliding member of a pulley of a continuously variable transmission is provided with a sealing material called a seal ring (generally a resin material such as a PTFE material). Since this seal ring has temperature dependence, the amount of oil leakage varies depending on the temperature. Even if the hydraulic oil discharge is limited to prevent a decrease in hydraulic pressure as in Patent Document 1, if the oil leaks from the sliding portion of the piston chamber and the air enters, the hydraulic oil discharge is limited. has no meaning.

JP 2001-41315 A

  SUMMARY OF THE INVENTION An object of the present invention is to provide a vehicle control device that can suppress the fuel consumption of an engine and the belt slip when returning from an idle stop in consideration of the leakage characteristics of a seal ring.

  In order to achieve the above object, the present invention provides a vehicle equipped with an engine and a belt-type continuously variable transmission, and includes an oil pump driven by the engine, a primary pulley and a secondary pulley of the continuously variable transmission. In a vehicle comprising pulley hydraulic pressure control means for controlling hydraulic pressure based on hydraulic pressure using the oil pump as a hydraulic source, and idle stop control means for automatically stopping the engine when a predetermined condition is satisfied, the primary A resin seal ring provided in the sliding portion of the piston chamber of the pulley and the secondary pulley, a time detection means for detecting an elapsed time from the automatic stop of the engine, and a temperature of the hydraulic oil of the continuously variable transmission When the elapsed time from the automatic stop of the engine reaches the predetermined time T, the engine is forcibly restarted. That a restart means, to provide a control device for a vehicle, wherein the time T when higher than when the oil temperature is low is set longer.

  The present invention is intended for an idle stop vehicle having only an oil pump driven by an engine as a pulley hydraulic source, and does not have a special hydraulic source such as an electric pump. Can not supply. For this reason, when the engine is stopped, oil may leak from the piston chamber of the pulley through the sliding portion with the passage of time, and air may enter the piston chamber. When air is mixed in, it takes time to fill the piston chamber with hydraulic oil when the engine is restarted, and when the engine is restarted next time, the belt slips and cannot start quickly.

  In the present invention, the elapsed time from the idle stop (automatic engine stop) is measured, and when the elapsed time reaches a predetermined time T, the engine is forcibly restarted, and the time T is increased as the oil temperature is higher. It is set long. In general, the higher the oil temperature, the lower the viscosity of the oil. Therefore, oil leakage from the sliding portion also increases, and it is considered that the time T should be set short. However, the seal ring provided on the sliding part of the pulley is a resin-based seal material, and this seal material has a property of expanding due to a rise in temperature, and the adhesion with the seal surface is increased. Decrease. In the present invention, paying attention to this point, the time T from the engine stop to the restart is set longer as the CVT oil temperature is higher. Since the temperature of the seal ring itself cannot be detected, the CVT oil temperature is used instead. Time T is determined based on the time when the amount of oil leakage from the piston chamber of the pulley is measured in advance for each temperature and the amount of oil leakage reaches the reference amount. If the idle stop time is within T, it is possible to prevent air from being mixed into the piston chamber of the pulley, and it is possible to prevent a problem in the boosting characteristics when the idle stop is restored. In this way, by appropriately controlling the idle stop time, it is possible to achieve both prevention of belt slip and reduction of fuel consumption and exhaust gas.

  In general, in the case of an idle stop vehicle equipped with a CVT, the idle stop itself is prohibited if the oil temperature of the CVT is equal to or lower than a lower limit temperature (for example, 20 ° C.). Therefore, the time T set by the present invention is set in a range where the oil temperature is higher than the idle stop prohibiting temperature. In addition, the set time T may be constant above the upper limit temperature (for example, 80 ° C.).

  As described above, according to the present invention, the resin-based seal ring is used for the sliding portions of the primary pulley and the secondary pulley, and when the elapsed time from the automatic engine stop reaches the predetermined time T, the engine is forcibly In addition to restarting, the time T is set longer as the oil temperature is higher, so that air can be prevented from entering the piston chamber of the pulley, and when the engine is restarted, it can start quickly without causing belt slippage. .

It is a figure showing the whole system of vehicles concerning the present invention. It is a skeleton figure which shows the structure of a continuously variable transmission. It is a detailed sectional view of a primary pulley and a secondary pulley. It is a perspective view which shows the joint part of various seal rings. It is the schematic of the hydraulic circuit for controlling a primary pulley and a secondary pulley. It is a time chart figure of an example of control of the present invention at the time of idle stop. It is a figure which shows the relationship between the amount of oil leaks from a piston chamber, and idle stop time. It is a flowchart figure of an example of the control method which concerns on this invention. It is a time chart figure at the time of the conventional idle stop return.

  Hereinafter, preferred embodiments of the present invention will be described with reference to examples.

  FIG. 1 shows an example of a vehicle system equipped with a continuously variable transmission according to the present invention. The output shaft 1 a of the engine 1 is connected to the drive shaft 32 via the continuously variable transmission 2. The continuously variable transmission 2 is provided with a torque converter 3, a transmission mechanism 4, a hydraulic control device 5, an oil pump 6 driven by the engine 1, and the like.

  The engine 1 and the continuously variable transmission 2 are controlled by an electronic control unit (ECU) 100. Signals are input from the various sensors 101 to 107 to the electronic control device 100. These sensors 101 to 107 include engine speed, vehicle speed (or secondary pulley speed), throttle opening (or accelerator opening), shift position, primary pulley speed (or turbine speed), brake signal, CVT oil temperature. It is a sensor which detects. In addition, an idle signal, a start signal, an engine water temperature, an intake air amount, an air conditioner signal, an ignition signal, and the like may be detected. For the sake of simplicity, FIG. 1 shows an example in which both the engine 1 and the continuously variable transmission 2 are controlled by a single electronic control unit 100. However, the engine 1 and the continuously variable transmission 2 are actually used. Are controlled by individual electronic control units, and both electronic control units are linked to each other via a communication bus.

  The electronic control unit 100 has an idle stop function of stopping the engine 1 (idle stop) when a predetermined condition is satisfied and restarting the engine when the predetermined condition is not satisfied. Conditions for permitting idle stop include, for example, when the vehicle speed is less than a certain value, the throttle opening is fully closed, and the vehicle deceleration is less than a predetermined value, or when the vehicle is stopped and the brake is on (depressing the brake pedal). It is. However, idling stop is not permitted when the CVT oil temperature is low, the engine water temperature is low, the electric load is large, the accelerator pedal is depressed, or the like. On the other hand, idle stop release (engine restart) conditions include, for example, brake OFF, accelerator pedal depression, and input of a vehicle speed signal.

  The electronic control device 100 also performs control of the continuously variable transmission 2 in addition to engine control. That is, the continuously variable transmission is determined by determining the target primary rotational speed according to a preset shift map according to the vehicle speed and the throttle opening, and controlling the solenoid valves 5a to 5c built in the hydraulic control device 5. 2 is controlled to the target value. The hydraulic control device 5 also has a function of controlling the hydraulic pressure supplied to the direct coupling clutch 86 and the reverse brake 85 built in the continuously variable transmission 2 described later. In this embodiment, an example in which the hydraulic control device 5 has three solenoid valves 5a to 5c has been shown, but in addition to this, for controlling the lock-up clutch 3a built in the torque converter 3, for line pressure control, etc. Another solenoid valve may be provided. Note that the hydraulic pressure source of the hydraulic control device 5 is only the oil pump 6 driven by the engine 1 described above, and no special oil pump such as an electric pump is provided.

  FIG. 2 shows an example of a schematic structure of the continuously variable transmission 2. The continuously variable transmission 2 includes a torque converter 3 and a continuously variable transmission mechanism 4. The turbine shaft 7 of the torque converter 3 is connected to the primary shaft 10 via a forward / reverse switching device 8. The forward / reverse switching device 8 transmits the rotation of the turbine shaft 7 to the primary shaft 10 by switching between forward and reverse. The continuously variable transmission mechanism 4 further includes a primary pulley 11, a secondary pulley 21, a V belt 15 wound between both pulleys, a secondary shaft 20, a differential device 30 that transmits power of the secondary shaft 20 to a drive shaft 32, and the like. ing. The turbine shaft 7 and the primary shaft 10 are arranged on the same axis, and the secondary shaft 20 and the drive shaft 32 are arranged parallel to the turbine shaft 7 and non-coaxially. Therefore, the continuously variable transmission 2 has a three-axis configuration as a whole. The V belt 15 used here is a known metal belt composed of a pair of endless tension bands and a number of blocks supported by these tension bands, for example.

  The forward / reverse switching device 8 includes a planetary gear mechanism 80, a reverse brake 85, and a direct coupling clutch 86. The reverse brake 85 and the direct coupling clutch 86 are wet multi-plate brakes and clutches, respectively. A sun gear 81 of the planetary gear mechanism 80 is connected to the turbine shaft 7 as an input member, and a ring gear 82 is connected to the primary shaft 10 as an output member. The planetary gear mechanism 80 is a single pinion system, the reverse brake 85 is provided between the carrier 84 supporting the pinion gear 83 and the transmission case, and the direct coupling clutch 86 is provided between the carrier 84 and the sun gear 81. When the direct coupling clutch 86 is released and the reverse brake 85 is engaged, the rotation of the turbine shaft 7 is reversed, decelerated, and transmitted to the primary shaft 10. Then, the drive shaft 32 rotates in the same direction as the engine rotation direction via the secondary shaft 20, so that the vehicle travels forward. Conversely, when the reverse brake 85 is released and the direct coupling clutch 86 is engaged, the carrier 84 and the sun gear 81 rotate together, so that the turbine shaft 7 and the primary shaft 10 are directly coupled. Then, since the drive shaft 32 rotates in the direction opposite to the engine rotation direction via the secondary shaft 20, a reverse traveling state is set.

  FIG. 3 shows a specific structure of the continuously variable transmission mechanism. The primary pulley 11 includes a fixed sheave 11a integrally formed on the primary shaft 10, and a movable sheave 11b supported on the primary shaft 10 so as to be axially movable and integrally rotatable. A cylinder 12 fixed to the primary shaft 10 is provided behind the movable sheave 11 b, and a piston chamber 13 is formed between the movable sheave 11 b and the cylinder 12. Shift control is performed by controlling the flow rate of the hydraulic oil to the piston chamber 13.

  A seal ring 14 is attached to the outer peripheral portion of the movable sheave 11 b of the primary pulley 11, and the oil leakage of the piston chamber 13 is suppressed by sliding the seal ring 14 on the inner peripheral surface of the cylinder 12. . The seal ring 14 is a resin seal ring such as a PTFE material having a square cross section, and the joint portion 14a has various shapes as shown in FIGS. In particular, in the case of step cuts such as (c) to (e) in FIG. 4, the amount of oil leakage from the joint portion is small compared to bias cuts such as (a) and (b), and the temperature dependence thereof. Therefore, step cut is preferable as the shape of the abutment portion of the seal ring 14. Even if the abutment portion is a step cut, the amount of oil leakage other than the abutment portion is temperature-dependent, and therefore, by applying the control method of the present invention, it is possible to appropriately suppress belt slip at the time of idling stop return. In addition, since the joint shape of the seal ring 14 is well-known, detailed description is abbreviate | omitted.

  The secondary pulley 21 includes a fixed sheave 21a formed integrally on the secondary shaft 20, and a movable sheave 21b supported on the secondary shaft 20 so as to be axially movable and integrally rotatable. A piston 22 fixed to the secondary shaft 20 is provided behind the movable sheave 21 b, and a piston chamber 23 is formed between the movable sheave 21 b and the piston 22. By controlling the hydraulic pressure in the piston chamber 23, a clamping pressure necessary for torque transmission is applied. A bias spring 24 that generates an initial clamping pressure is disposed in the piston chamber 23. Similar to the movable sheave 11b of the primary pulley 11, a seal ring 25 is attached to the outer peripheral portion of the piston 22, and the piston ring 23 slides on the inner peripheral surface of the movable sheave 21b. Oil leakage is suppressed. The shape of the seal ring 25 is the same as that of the seal ring 14.

  One end portion of the secondary shaft 20 extends toward the engine side, and the output gear 27 is fixed to this end portion. The output gear 27 meshes with the ring gear 31 of the differential device 30, and power is transmitted from the differential device 30 to the drive shaft 32 extending left and right to drive the wheels.

  FIG. 5 shows an example of a hydraulic circuit for controlling the primary pulley 11 and the secondary pulley 21 of the continuously variable transmission 2 in the hydraulic control device 5. In FIG. 5, valves that are not directly related to the control of the present invention, such as manual valves and garage shift valves, are omitted. The hydraulic pressure discharged by the oil pump 6 is adjusted to a predetermined line pressure by the regulator valve 51, and then hydraulic oil is supplied to the piston chamber 13 of the primary pulley 11 via the speed change control valve 52. Hydraulic oil is supplied to the piston chamber 23 of the secondary pulley 21 through 53. The transmission control valve 52 is a flow control valve, and the clamping pressure control valve 53 is a pressure control valve. The shift control valve 52 and the clamping pressure control valve 53 are equipped with solenoids 52 a and 53 a, respectively, and the primary hydraulic pressure and the secondary hydraulic pressure are controlled by controlling these solenoids by the electronic control device 100. The line pressure is also supplied to a ratio check valve (pressure control valve) 54. The ratio check valve 54 receives the output pressure of the clamping pressure control valve 53 as a signal pressure, and shift control is performed during closing control while the vehicle is stopped. Hydraulic pressure is supplied to the primary pulley 11 instead of the valve 52. A small orifice 55 is provided in the oil passage between the ratio check valve 54 and the primary pulley 11. This orifice 55 is for preventing a sudden shift when shifting to the closing control when the vehicle is stopped.

  Shift control during normal driving is performed by the shift control valve 52. When the vehicle is stopped (or at an extremely low vehicle speed immediately before and immediately after stopping), the ratio of oil supply from the shift control valve 52 to the primary side when maintaining the maximum gear ratio. Switch to check valve 54. The reason for switching the oil path at the time of the maximum shift is to prevent the primary hydraulic pressure from escaping in the direction of discharging the primary hydraulic pressure at the low-side shift (the winding diameter of the primary pulley is the smaller diameter side). By switching to the ratio check valve 54, the primary hydraulic pressure is maintained. This is called closed control. Although the output pressure of the ratio check valve 54 is regulated by the clamping pressure control valve 53, that is, the secondary hydraulic pressure, it does not control the gear ratio, so a small-diameter orifice 55 is set to prevent sudden gear change at the time of switching. Yes.

  Thus, since the orifice 55 is provided between the ratio check valve 54 and the primary pulley 11, it takes time to supply and discharge hydraulic oil to and from the primary pulley 11 when the vehicle is stopped compared to the secondary pulley 21. Therefore, if air enters the piston chamber 13 of the primary pulley 11 during idle stop, it takes time to fill the piston chamber 13 with hydraulic oil when the next engine is restarted, and the belt slips. In the present invention, in order to solve such a problem, control as described later is performed.

  Next, a control method according to the present invention during idle stop will be described with reference to FIG. FIG. 6 shows changes in the engine speed, idle stop state, idle stop stop time counter, idle stop return request flag, and secondary clamping pressure and primary clamping pressure over time. At time t1, the engine stops and idle stop is started. From this point, the idle stop stop time counter starts timing. When the stop time counter reaches the set time T corresponding to the CVT oil temperature at that time (time t2), a forced return request for idle stop is made from the CVT, thereby returning to idle stop (time t3) and restarting the engine. The Since the oil pump is driven as the engine is restarted, hydraulic pressure is supplied to the primary pulley and the secondary pulley, and the pulley clamping pressure increases. At this time, the idle stop stop time is limited to the set time T, so that air does not enter the piston chamber of the pulley, and the time for filling the piston chamber with hydraulic oil at the next engine restart can be shortened. , Belt slippage can be suppressed.

  FIG. 7 shows the relationship between the amount of oil leakage from the sliding portion of the piston chamber and time. As shown in FIG. 7, the amount of oil leakage is determined by parameters of the CVT oil temperature and time, and the higher the CVT oil temperature, the smaller the time gradient of the leakage amount. The reason is that the seal rings 14 and 25 provided on the sliding portion of the pulley are resin-based sealing materials, and since this sealing material has a property of expanding due to a temperature rise, the amount of leakage decreases when the oil temperature rises. It is. For example, when the CVT oil temperature is 40 ° C., 60 ° C., and 80 ° C., the time for the leakage amount to reach the reference leakage amount is set as T1, T2, and T3, respectively, and these times are set as the set time T. The reference leakage amount is, for example, the maximum amount of oil leakage from the piston chamber of the primary pulley that does not cause a problem in the boosting characteristics at the time of idle stop return (maximum leakage amount considered that air does not enter the piston chamber). . Table 1 shows a specific example of the set time T according to the CVT oil temperature, and the longer the CVT oil temperature is, the longer it is set.

  In Table 1, only three types of CVT oil temperatures of 40 ° C., 60 ° C., and 80 ° C. are set, but the time T at those intermediate temperatures can be calculated by proportional calculation or interpolation calculation. Note that it is not necessary to set the time T because idle stop itself is prohibited below the lower limit temperature (for example, 20 ° C.). The time T is constant above the upper limit temperature (for example, 80 ° C.).

  FIG. 8 shows the flow of the control method during idle stop according to the present invention. When starting, first, an idle stop operation (engine stop) is commanded (step S1), and the engine stop time after starting the idle stop is counted (step S2). Next, the engine stop time is compared with a time T set according to the CVT oil temperature (step S3). If it is determined that the stop time is longer than the set time T, the electronic control unit 100 issues an idle stop return request signal (step S4) and performs an idle stop return (engine restart) (step S5). On the other hand, when it is determined that the engine stop time is equal to or shorter than the set time T, the idle stop is continued (step S6), and it is determined whether there is a return request from another system (step S7). The return requests from other systems include brake OFF, accelerator pedal depression, CVT oil temperature is low, engine water temperature is low, and battery capacity is low. If there is a return request from another system, the idle stop return is immediately performed (step S5), and if there is no return request, the process returns to step S3. With the above control, oil leakage more than necessary from the sliding portion of the pulley can be suppressed, and air mixing into the piston chamber can be prevented.

  FIG. 5 shows an example in which the speed change control valve 52 and the clamping pressure control valve 53 themselves are solenoid valves. However, this is only an example, and for example, a configuration in which a control valve and a solenoid valve are combined may be used. The solenoid valve may be either a linear solenoid valve or a duty solenoid valve.

DESCRIPTION OF SYMBOLS 1 Engine output shaft 2 Continuously variable transmission 3 Torque converter 4 Transmission mechanism 5 Planetary gear apparatus 6 Oil pump 8 Forward / reverse switching apparatus 11 Primary pulley 11b Movable sheave 13 Piston chamber 14 Seal ring 15 Belt 21 Secondary pulley 23 Piston chamber 25 Seal ring 52 Shift control valve (pulley hydraulic pressure control means)
53 Nipping pressure control valve (pulley hydraulic pressure control means)
54 Ratio check valve 55 Orifice 85 Reverse rotation brake 86 Direct coupling clutch 100 Electronic controller 101 Engine speed sensor 102 Vehicle speed sensor 103 Throttle opening sensor 104 Shift position sensor 105 Primary pulley speed sensor 106 Brake sensor 107 Oil temperature sensor

Claims (1)

A vehicle equipped with an engine and a belt-type continuously variable transmission,
An oil pump driven by the engine;
Pulley hydraulic control means for controlling the hydraulic pressure of the primary pulley and the secondary pulley of the continuously variable transmission based on the hydraulic pressure using the oil pump as a hydraulic source;
In a vehicle provided with idle stop control means for automatically stopping the engine when a predetermined condition is satisfied,
A resin seal ring provided in a sliding portion of the piston chamber of the primary pulley and the secondary pulley;
Time detection means for detecting an elapsed time from the automatic stop of the engine;
Oil temperature detecting means for detecting the temperature of hydraulic oil of the continuously variable transmission;
Restarting means for forcibly restarting the engine when the elapsed time from the automatic stop of the engine reaches a predetermined time T;
The vehicle control device characterized in that the time T when the oil temperature is high is set longer than when the oil temperature is low.

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