Automatic transmission control device

Abstract

To provide a control device of an automatic transmission capable of enhancing a deposit removal effect.SOLUTION: A control device of an automatic transmission includes: an operation lever 71 for accepting operation of a shift stage of an automatic transmission 101 in a manual mode; a PCM 70 for controlling the shift stage of the automatic transmission 101 according to a prescribed shift stage schedule, and changing the shift stage of the automatic transmission 101 according to the operation in the manual mode; and a compression leakage detection part for detecting compression leakage that is a phenomenon where air is leaked through a suction port 11 or an exhaust port 12 from a combustion chamber C during a compression process. The PCM 70 executes shift stage schedule change control of changing switching vehicle speed of the shift stage set in the shift stage schedule to a high speed side when the compression leakage is detected, and manual mode prohibition control of prohibiting change of the shift stage of the automatic transmission 101 in the manual mode when the shift stage schedule change control is executed.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a control device for an automatic transmission incorporated in a power transmission system of an engine of a vehicle or the like. [Background technology]

[0002] In engines equipped with intake and exhaust ports connected to a combustion chamber and intake and exhaust valves that open and close these ports, deposits can form between the intake valve and the valve seat or between the exhaust valve and the valve seat. The buildup of deposits can cause compression leakage, in which compressed air leaks from the combustion chamber through the intake or exhaust port. Compression leakage can prevent the air-fuel mixture in the combustion chamber from burning properly, resulting in misfires.

[0003] Patent Document 1 discloses an engine that incorporates measures to prevent the buildup of deposits. In this engine, when deposit buildup is detected, the engine speed at which lockup, in which engine output is transmitted directly to the drive wheels via the automatic transmission, is released is set to a lower speed than during normal operation. By lowering the lockup release speed, the range in which the engine output shaft rotates in sync with the drive wheels is expanded, increasing the likelihood that deposits will be removed by the operation of the intake or exhaust valves themselves. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6593384 Summary of the Invention [Problem to be solved by the invention]

[0005] Another approach to preventing deposit buildup is to change the preset gear shift speed in the automatic transmission's gear shift schedule to expand the range in which engine speeds are maintained at high rpm. Expanding the range of high rpm increases the likelihood of deposit removal. However, even if the gear shift speed is changed, if the driver manually operates the gear, the deposit removal effect will be compromised.

[0006] An object of the present invention is to provide a control device for an automatic transmission that can enhance the deposit removal effect. [Means for solving the problem]

[0007] An automatic transmission control device according to one aspect of the present invention is a control device for an automatic transmission connected to an engine having a combustion chamber, an intake passage connected to the combustion chamber via an intake port, an exhaust passage connected to the combustion chamber via an exhaust port, and an intake valve and an exhaust valve that open and close the intake port and the exhaust port, the control device including an operation lever that accepts a driver's operation to select a manual mode and to operate a gear position of the automatic transmission in the manual mode, and the automatic transmission controls the gear positions of the automatic transmission in accordance with a preset gear position schedule, and controls the automatic transmission in accordance with the operation accepted by the operation lever in the manual mode. Accordingly, the system is provided with a control unit that changes the gear stage of the automatic transmission, and a compression leak detection unit that detects compression leak, which is a phenomenon in which air leaks from the combustion chamber through the intake port or the exhaust port during the compression stroke, and when compression leak is detected by the compression leak detection unit, the control unit executes gear stage schedule change control that changes the gear stage switching vehicle speed set in the gear stage schedule to a higher speed, and manual mode prohibition control that prohibits changing the gear stage of the automatic transmission in the manual mode even if the manual mode is selected when the gear stage schedule change control is executed.

[0008] According to this control device, when a compression leak is detected, the gear shifting speed is changed to a higher speed through gear shift schedule change control. In other words, when a compression leak is detected, the gear shifting speed applied at a certain vehicle speed can be changed to a lower speed than during normal driving. This expands the range in which the engine speed is maintained at high speed, increasing the likelihood of deposit removal through the high-speed operation of the intake or exhaust valve itself. However, if the driver applies manual mode and changes the gear while this gear shift schedule change control is being executed, the effect of expanding the high-speed range is lost, and the deposit removal effect may be reduced. Therefore, when the gear shift schedule change control is being executed, manual mode prohibition control is executed. This allows the gear shift schedule change control to achieve the deposit removal effect originally expected.

[0009] It is desirable that the above-mentioned automatic transmission control device further includes a display unit that displays information for the driver, and that when the control unit executes the manual mode prohibition control, the control unit causes the display unit to display information indicating that operation of the gear position of the automatic transmission in the manual mode is prohibited.

[0010] This control device can notify the driver through the display unit that the manual mode prohibition control is being executed, which can encourage the driver to avoid using the manual mode or to recognize the cause of the malfunction in manual operation and prevent the driver from feeling distrustful.

[0011] In the above-mentioned automatic transmission control device, the control unit Gear shift schedule change control When the above is executed, it is desirable to change the engine speed to a lower speed to release the lockup state in which the engine output is directly transmitted to the drive wheels via the automatic transmission.

[0012] According to this control device, by changing the lockup release speed to a lower speed, the region in which the engine output shaft rotates in sync with the drive wheels is expanded, increasing the possibility of deposit removal by the operation of the intake or exhaust valve itself. By executing this control of the lockup release speed in conjunction with the gear stage schedule change control, the deposit removal effect can be further improved.

[0013] In the above-mentioned automatic transmission control device, it is desirable that the control unit executes suppression control to suppress a decrease in engine speed when compression leakage is detected by the compression leakage detection unit, and executes the gear stage schedule change control and the manual mode prohibition control when compression leakage is still detected after execution of the suppression control.

[0014] According to this control device, various types of suppression controls to suppress a decrease in engine speed are performed first, and if the suppression controls are unable to suppress compression leakage, the gear stage schedule change control and the manual mode prohibition control are executed, thereby avoiding unnecessary restrictions on the driver's opportunities to perform manual operation.

[0015] The aforementioned Deterrent Control As examples of such control, it is possible to prohibit an idle stop control that stops the engine when a predetermined idle stop condition is met, or to apply an idle speed increase control that sets the idle speed of the engine to a higher speed than normal. These controls have the advantage of not imposing a large control load and not restricting the manual operation of the driver. [Effects of the Invention]

[0016] According to the present invention, it is possible to provide a control device for an automatic transmission that can enhance the deposit removal effect. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 is a system diagram showing the overall configuration of an engine to which an automatic transmission control device according to the present invention is applied. [Figure 2] FIG. 2 is a cross-sectional view showing the intake and exhaust valves and their valve operating mechanisms in detail. [Figure 3] FIG. 3 is a plan view schematically showing the structure of a power transmission system between the engine and the wheels. [Figure 4] FIG. 4 is a functional block diagram showing a control system for the engine and automatic transmission. [Figure 5] FIG. 5 is a graph showing a gear shift schedule for an automatic transmission. [Figure 6] FIG. 6 is a flowchart showing an example of countermeasure control against deposit adhesion to the valve seat. [Figure 7] FIG. 7 is a diagram for explaining a method for calculating the compression state index value. [Figure 8] FIG. 8 is a chart showing the relationship between engine speed, gear position, and lockup release speed during normal operation. [Figure 9] FIG. 9 is a chart showing the relationship between the engine speed, the gear position, and the lockup release speed when a compression leakage abnormality is detected. DETAILED DESCRIPTION OF THE INVENTION

[0018] Hereinafter, a control device for an automatic transmission according to an embodiment of the present invention will be described in detail with reference to the drawings. In this embodiment, an automatic transmission is incorporated into a power transmission system of an engine mounted on a vehicle such as an automobile as a power source for driving the vehicle, and a control device for the automatic transmission is incorporated into a control device for the vehicle (PCM 70, which will be described later).

[0019] [Overall engine configuration] FIG. 1 is a system diagram showing the overall configuration of an engine. The engine 1 shown in FIG. 1 is a cycle diesel engine. The engine 1 includes an engine body 2, an intake passage 30 through which intake air introduced into the engine body 2 flows, an exhaust passage 40 through which exhaust gas discharged from the engine body 2 flows, an EGR device 50 that recirculates a portion of the exhaust gas flowing through the exhaust passage 40 to the intake passage 30, and a supercharger 60 that supercharges the intake air flowing through the intake passage 30. The operation of the engine 1 is controlled by a PCM 70 (control unit). An automatic transmission 101 is connected to the output shaft of the engine body 2.

[0020] The engine body 2 is a multi-cylinder engine having a plurality of cylinders 2a arranged in a direction perpendicular to the plane of the paper in FIG. 1 (see also FIG. 3, which will be described later). The engine body 2 includes a cylinder block 3, a cylinder head 4, and a plurality of pistons 5. The cylinders 2a are formed by the cylinder block 3 and the cylinder head 4. That is, a plurality of cylindrical spaces corresponding to the plurality of cylinders 2a are formed inside the cylinder block 3, and the cylinder head 4 is attached to the upper surface of the cylinder block 3 so as to close off the cylindrical spaces from above. A piston 5 is housed in each cylinder 2a so as to be able to slide back and forth.

[0021] A combustion chamber C is formed above the piston 5 of each cylinder 2a. Each combustion chamber C is a space defined by the lower surface of the cylinder head 4, the side circumferential surface (cylinder liner) of the cylinder 2a, and the crown surface of the piston 5. The combustion chamber C is supplied with fuel injected from a fuel injection valve 9, which will be described later. The piston 5 receives the combustion energy of the fuel supplied to the combustion chamber C and reciprocates up and down. Note that, since the engine 1 of this embodiment is a diesel engine, fuel containing diesel is used as the fuel supplied to the combustion chamber C.

[0022] A crankshaft 7, which is the output shaft of the engine body 2, is provided below the pistons 5 and in the lower part of the cylinder block 3. The crankshaft 7 is connected to the pistons 5 of each cylinder 2a via connecting rods 8, and rotates around its central axis in response to the reciprocating motion (up and down movement) of the pistons 5.

[0023] A crank angle sensor SN1 and a water temperature sensor SN2 are attached to the cylinder block 3. The crank angle sensor SN1 detects the crank angle, which is the rotation angle of the crankshaft 7, and the engine speed, which is the rotation speed of the crankshaft 7. The water temperature sensor SN2 detects the temperature of the cooling water flowing inside the cylinder block 3 and the cylinder head 4, i.e., the engine water temperature.

[0024] Fuel injection valves 9 and glow plugs 10 are attached to the cylinder head 4. The fuel injection valves 9 inject fuel into the combustion chambers C of each cylinder 2a. The glow plugs 10 heat the combustion chambers C of each cylinder 2a. One fuel injection valve 9 and one glow plug 10 are provided for each cylinder 2a.

[0025] The fuel injection valve 9 is attached to the cylinder head 4 so that its tip is exposed to the combustion chamber C. A plurality of nozzle holes (not shown) that serve as fuel outlets are formed at the tip of the fuel injection valve 9. The fuel injected from each nozzle hole is burned by self-ignition in the combustion chamber C, which has been made hot and pressurized by the compression action of the piston 5.

[0026] The glow plug 10 is attached to the cylinder head 4 so that its tip is exposed to the combustion chamber C. The tip of the glow plug 10 is equipped with a heating element that generates heat when current is applied. The heating element quickly heats up to a high temperature when current is applied, thereby heating the combustion chamber C. The glow plug 10 operates when the engine 1 is cold to heat the combustion chamber C. Specifically, the glow plug 10 operates when the engine water temperature at start-up, i.e., the temperature detected by the water temperature sensor SN2 at start-up of the engine 1, is equal to or lower than a predetermined first temperature. After the engine 1 has started, the glow plug 10 continues to operate, i.e., to heat the combustion chamber C, until the engine water temperature reaches a second temperature higher than the first temperature.

[0027] The cylinder head 4 is formed with intake ports 11 and exhaust ports 12. The intake ports 11 connect the combustion chambers C of each cylinder 2a to the intake passage 30. The exhaust ports 12 connect the combustion chambers C of each cylinder 2a to the exhaust passage 40. An intake valve 13 is provided in the intake port 11 of each cylinder 2a, and an exhaust valve 14 is provided in the exhaust port 12 of each cylinder 2a.

[0028] The cylinder head 4 is equipped with an intake valve train 15 and an exhaust valve train 16. The intake valve train 15 drives the intake valve 13 of each cylinder 2a to open and close in conjunction with the rotation of the crankshaft 7. The exhaust valve train 16 drives the exhaust valve 14 of each cylinder 2a to open and close in conjunction with the rotation of the crankshaft 7. The intake valve 13 periodically opens and closes the opening of the intake port 11 on the combustion chamber C side in response to the drive of the intake valve train 15. The exhaust valve 14 periodically opens and closes the opening of the exhaust port 12 on the combustion chamber C side in response to the drive of the exhaust valve train 16.

[0029] The intake passage 30 is a passage for introducing intake air into the combustion chamber C of each cylinder 2a. The intake passage 30 has an intake manifold 30a and a surge tank 30b in a downstream portion close to the engine body 2. The surge tank 30b is a tank that provides an expanded space for equalizing the amount of intake air introduced to each cylinder 2a. The intake manifold 30a includes multiple branch pipes that connect the surge tank 30b to the intake ports 11 of each cylinder 2a. The portion of the intake passage 30 upstream of the surge tank 30b is formed in the shape of a single pipe.

[0030] An air cleaner 31, an intercooler 32, and an intake shutter valve 33 are sequentially provided in the intake passage 30 upstream of the surge tank 30b. The air cleaner 31 is a filter that removes foreign matter from the intake air. The intercooler 32 is a heat exchanger that cools the intake air compressed by the supercharger 60. The intake shutter valve 33 is an electrically operated butterfly valve that is provided in the intake passage 30 in an openable and closable manner to throttle the flow rate of the intake air.

[0031] An air flow sensor SN3 and an intake pressure sensor SN4 are attached to the intake passage 30. The air flow sensor SN3 is a sensor that detects the flow rate of intake air introduced into the engine body 2, and is disposed downstream of the air cleaner 31 in the intake passage 30. The intake pressure sensor SN4 is a sensor that detects the pressure of the intake air introduced into the engine body 2, and is disposed in the surge tank 30b.

[0032] The exhaust passage 40 is a passage for discharging exhaust gas discharged from the combustion chamber C of each cylinder 2a to the outside. The exhaust passage 40 has an exhaust manifold 40a in an upstream portion close to the engine body 2. The exhaust manifold 40a includes a plurality of branch pipes that communicate with the exhaust ports 12 of each cylinder 2a, and an exhaust collecting section where the branch pipes collect. The portion of the exhaust passage 40 downstream of the exhaust manifold 40a is formed in a single pipe shape.

[0033] A catalytic device 41 is provided downstream of the exhaust manifold 40a in the exhaust passage 40. The catalytic device 41 incorporates an oxidation catalyst 41a that oxidizes and detoxifies CO and HC in the exhaust gas, and a DPF (diesel particulate filter) 41b that collects particulate matter contained in the exhaust gas.

[0034] The supercharger 60 is a so-called two-stage supercharger, and includes a first supercharger 61 and a second supercharger 62 arranged in series. The first supercharger 61 is a turbocharger including a first compressor 61a arranged in the intake passage 30, and a first turbine 61b coaxially connected to the first compressor 61a and arranged in the exhaust passage 40. The first compressor 61a is arranged in a portion of the intake passage 30 between the air cleaner 31 and the intercooler 32. The first turbine 61b is arranged in a portion of the exhaust passage 40 upstream of the catalytic device 41.

[0035] Similarly, the second supercharger 62 is a turbocharger including a second compressor 62a disposed in the intake passage 30 and a second turbine 62b coaxially connected to the second compressor 62a and disposed in the exhaust passage 40. The second compressor 62a is disposed in a portion of the intake passage 30 downstream of the first compressor 61a, i.e., a portion between the first compressor 61a and the intercooler 32. The second turbine 62b is disposed in a portion of the exhaust passage 40 upstream of the first turbine 61b.

[0036] An intake bypass passage 63 is connected to the intake passage 30. The intake bypass passage 63 is a passage for bypassing the second compressor 62a. An electrically operated bypass valve 63a is provided in the intake bypass passage 63 so as to be able to open and close.

[0037] A first exhaust bypass passage 64 and a second exhaust bypass passage 65 are connected to the exhaust passage 40. The first exhaust bypass passage 64 is a passage for bypassing the first turbine 61b. The second exhaust bypass passage 65 is a passage for bypassing the second turbine 62b. An electric wastegate valve 64a is provided in the first exhaust bypass passage 64 so that it can be opened and closed. An electric regulator valve 65a is provided in the second exhaust bypass passage 65 so that it can be opened and closed.

[0038] When supercharging is performed by the first supercharger 61, the wastegate valve 64a is closed. As a result, exhaust gas discharged from the engine body 2 is introduced into the first turbine 61b, and the first turbine 61b is rotationally driven by the exhaust gas. The first compressor 61a rotates in conjunction with the first turbine 61b, thereby compressing and sending the intake air downstream. In other words, the first supercharger 61 achieves supercharging by compressing the intake air in the intake passage 30 and sending it to the engine body 2.

[0039] When supercharging is performed by the second supercharger 62, the regulator valve 65a and the bypass valve 63a are closed. As a result, exhaust gas discharged from the engine body 2 is introduced into the second turbine 62b, and the second turbine 62b is rotationally driven by the exhaust gas. The second compressor 62a rotates in conjunction with the second turbine 62b, thereby compressing and sending the intake air downstream. In other words, the second supercharger 62 achieves supercharging by compressing the intake air in the intake passage 30 and sending it to the engine body 2.

[0040] The EGR device 50 includes an EGR passage 51, an EGR cooler 52, and an EGR valve 53. The EGR passage 51 is a passage for recirculating exhaust gas from the exhaust passage 40 to the intake passage 30, and connects the exhaust passage 40 and the intake passage 30 to each other. The EGR passage 51 connects a portion of the exhaust passage 40 upstream of the second turbine 62b to a portion of the intake passage 30 between the intake shutter valve 33 and the surge tank 30b. The EGR cooler 52 is a heat exchanger that cools the exhaust gas recirculated to the intake passage 30 through the EGR passage 51, i.e., the EGR gas. The EGR valve 53 is an electrically operated valve provided in the EGR passage 51 to adjust the amount of recirculated exhaust gas, i.e., the EGR amount.

[0041] [Intake and exhaust valve details] 2 is a cross-sectional view showing the intake valve 13 and exhaust valve 14 of the engine body 2 and their valve operating mechanisms 15, 16 in detail. The intake valve 13 has a stem portion 13a and an umbrella portion 13b. The stem portion 13a is a vertically long, cylindrical member supported by the cylinder head 4 so as to be slidable in the axial direction (vertical direction). The umbrella portion 13b is a disk-shaped member capable of closing the opening of the intake port 11 on the combustion chamber C side, and is formed so as to expand in diameter from the lower end of the stem portion 13a. Similarly, the exhaust valve 14 has a cylindrical stem portion 14a supported by the cylinder head 4 and an umbrella portion 14b that closes the opening of the exhaust port 12 on the combustion chamber C side.

[0042] An intake-side valve seat 11a and an exhaust-side valve seat 12a are attached to the cylinder head 4. The intake-side valve seat 11a is a ring-shaped member attached to the opening of the intake port 11 on the combustion chamber C side, and comes into close contact with the periphery of the head portion 13b of the intake valve 13 when the intake valve 13 is closed. The exhaust-side valve seat 12a is a ring-shaped member attached to the opening of the exhaust port 12 on the combustion chamber C side, and comes into close contact with the periphery of the head portion 14b of the exhaust valve 14 when the exhaust valve 14 is closed.

[0043] The intake valve train 15 includes a camshaft 21, a swing arm 23, and a valve spring 25. The camshaft 21 rotates in conjunction with the crankshaft 7 via a transmission member such as a timing chain. The camshaft 21 includes a shaft portion 21a extending in the direction in which the cylinders 2a are arranged, and multiple cam portions 21b provided on the shaft portion 21a at positions corresponding to the intake valves 13 of each cylinder 2a. The swing arm 23 is supported so as to be able to swing below the cam portions 21b of each cylinder 2a. The valve spring 25 is attached to the cylinder head 4 in a state in which it biases the intake valves 13 in a closing direction. As the camshaft 21 rotates, the intake valves 13 receive downward pressing force transmitted from the cam portion 21b via the swing arm 23, causing them to open periodically. On the other hand, when the pressing force is not acting, the upward biasing force of the valve spring 25 keeps the intake valve 13 in a closed state in which the head portion 13b is in close contact with the valve seat 11a.

[0044] Similarly, the exhaust valve mechanism 16 includes a camshaft 22, a swing arm 24, and a valve spring 26. The camshaft 22 is a shaft that rotates in conjunction with the crankshaft 7 and includes a shaft portion 22a and multiple cam portions 22b provided on the shaft portion 22a at positions corresponding to the exhaust valves 14 of the respective cylinders 2a. The swing arm 24 is swingably supported below the cam portions 22b of the respective cylinders 2a. The valve spring 26 biases the exhaust valves 14 in a closing direction. As the camshaft 22 rotates, the exhaust valves 14 receive a downward pressing force transmitted from the cam portion 22b via the swing arm 24, causing them to periodically open. On the other hand, when this pressing force is not acting, the upward biasing force of the valve spring 26 maintains the exhaust valve 14 in a closed state in which the head portion 14b is in close contact with the valve seat 12a.

[0045] [Power system] FIG. 3 is a plan view showing a schematic structure of a power transmission system that transmits the output of the engine 1 to the wheels W1 (drive wheels) of the vehicle. The vehicle in this example is a front-engine, rear-wheel-drive (FR) vehicle. Therefore, in FIG. 3, the wheels W1 are the rear wheels, and the engine body 2 is located in an engine room at the front of the vehicle. Note that FIG. 3 shows an in-line four-cylinder engine body 2 having four cylinders 2a arranged in a row, but the number and arrangement of the cylinders 2a can be changed as appropriate.

[0046] The power transmission system of the vehicle in this embodiment includes an automatic transmission 101 connected to the engine main body 2, a propeller shaft 102 extending rearward from the automatic transmission 101, a differential 103 connected to the rear end of the propeller shaft 102, and a pair of drive shafts 104 extending left and right from the differential 103. A wheel W1 is attached to each end of each drive shaft 104 in the vehicle width direction. The output rotation of the engine main body 2 is changed in speed by the automatic transmission 101 and then input to the differential 103 via the propeller shaft 102. The rotation input to the differential 103 is transmitted to each wheel W1 via the left and right drive shafts 104.

[0047] The automatic transmission 101 includes a torque converter 110 and a transmission body 120. The torque converter 110 is a fluid clutch that transmits the output rotation of the engine body 2, i.e., the rotation of the crankshaft 7, to the transmission body 120 via a working fluid. The transmission body 120 transmits the rotation input from the torque converter 110 to the wheels W1 while changing the speed.

[0048] The torque converter 110 incorporates a pump impeller 111 that rotates integrally with the crankshaft 7 of the engine body 2, a turbine runner 112 that is disposed opposite the pump impeller 111, and a stator 113 that is disposed between the pump impeller 111 and the turbine runner 112. The rotation of the pump impeller 111 is transmitted to the turbine runner 112 via the working fluid in the torque converter 110. The rotation of the turbine runner 112 is input to the transmission body 120 via a turbine shaft 114.

[0049] A lock-up clutch 115 is provided inside the torque converter 110. The lock-up clutch 115 is a clutch that connects and disconnects the crankshaft 7 of the engine main body 2 and the turbine runner 112. When the lock-up clutch 115 is engaged to connect the crankshaft 7 and the turbine runner 112, the crankshaft 7 and the turbine shaft 114 (the input shaft of the transmission main body 120) are mechanically connected without the intervention of the working fluid. This allows the rotational force of the crankshaft 7 to be transmitted directly to the wheel W1. In other words, the lock-up clutch 115 is a clutch that directly connects the output shaft (crankshaft 7) of the engine 1 and the wheel W1.

[0050] Engaging lockup clutch 115 improves power transmission efficiency. However, if lockup clutch 115 is engaged when engine speed or vehicle speed is low, vibrations from engine 1 are more likely to be transmitted to the vehicle. For this reason, lockup clutch 115 is engaged under specified conditions except when engine speed or vehicle speed is low, and is released (disengaged) when engine speed or vehicle speed is low.

[0051] The transmission main body 120 incorporates a multi-stage transmission mechanism 121 capable of achieving multiple gear stages with different reduction ratios. The transmission mechanism 121 includes a gear mechanism 122 that combines multiple planetary gear sets, multiple frictional engagement elements (not shown) including clutches and brakes that are engaged or disengaged to switch the power transmission path of the gear mechanism 122, and a hydraulic control valve 123 ( FIG. 4 ) consisting of a solenoid valve or the like that controls the hydraulic pressure supplied to each frictional engagement element to switch between engagement and disengagement. The hydraulic control valve 123 engages or disengages the appropriate frictional engagement elements, thereby achieving a desired gear stage in the transmission mechanism 121 according to the vehicle speed, etc. The output rotation of the torque converter 110, i.e., the rotation of the turbine shaft 114, is changed in speed at a reduction ratio corresponding to the gear stage of the transmission mechanism 121 and then transmitted to the wheels W1 via the propeller shaft 102 and the drive shaft 104.

[0052] The automatic transmission 101 is originally designed to automatically set the gear position according to the vehicle speed, etc., but is also capable of supporting a manual mode in which the driver manually selects the gear position. To enable the manual operation, the vehicle is provided with an operating lever 71. The operating lever 71 receives a selection operation from the driver to select the manual mode from the normal automatic transmission mode, and to operate the gear position of the automatic transmission 101 in the manual mode.

[0053] [Control system] 4 is a functional block diagram showing a control system for the engine 1 and automatic transmission 101. The PCM 70 shown in this diagram is a microprocessor for overall control of the engine 1 and automatic transmission 101, and is composed of a well-known CPU, ROM, RAM, etc. The PCM 70 corresponds to the "control unit" in the present invention.

[0054] Information detected by various sensors is input to the PCM 70. For example, information detected by a crank angle sensor SN1, a water temperature sensor SN2, an air flow sensor SN3, and an intake pressure sensor SN4, such as crank angle, engine speed, engine water temperature, intake air flow rate, and intake pressure, is sequentially input to the PCM 70.

[0055] The vehicle is also provided with an accelerator sensor SN5, a vehicle speed sensor SN6, and a shift position sensor SN7. The accelerator sensor SN5 detects the opening of the accelerator pedal operated by the driver of the vehicle, i.e., the accelerator opening. The vehicle speed sensor SN6 detects the traveling speed of the vehicle, i.e., the vehicle speed. The shift position sensor SN7 detects the currently set gear position (gear position) of the automatic transmission 101. The detection information from these sensors SN5, SN6, and SN7 is also sequentially input to the PCM 70.

[0056] The PCM 70 controls each part of the engine 1 and the automatic transmission 101 based on input information from each of the sensors SN1 to SN7. The PCM 70 is electrically connected to the fuel injector 9, glow plug 10, intake shutter valve 33, EGR valve 53, bypass valve 63a, wastegate valve 64a, and regulator valve 65a, as well as to the lock-up clutch 115 and hydraulic control valve 123 of the automatic transmission 101. The PCM 70 outputs control signals generated based on input information from each of the sensors SN1 to SN7 to these devices.

[0057] The vehicle is equipped with a display unit 72 that displays various types of information. The display unit 72 is, for example, a liquid crystal display, an indicator, or the like, disposed on an instrument panel located opposite the driver's seat. The PCM 70 causes the display unit 72 to display predetermined information. In this embodiment, in addition to normal displays such as the driving state, the PCM 70 causes the display unit 72 to display information about the gear selected in manual mode for the automatic transmission 101, and further information that changing the gear in manual mode is prohibited.

[0058] [Gear shift schedule change control] Regarding the control of the automatic transmission 101, the PCM 70 sets the gear of the automatic transmission 101 in accordance with a predetermined gear schedule. In this embodiment, when a compression leak in a combustion chamber C, which will be described later, is detected, the PCM 70 executes gear schedule change control to change the setting of the gear schedule. This point will be described with reference to FIG. 5.

[0059] 5 is a graph showing a gear shift schedule for the automatic transmission 101, with the vertical axis representing the throttle opening (the opening of the intake shutter valve 33) and the horizontal axis representing the vehicle speed of the vehicle equipped with the engine 1. In FIG. 5, solid lines SU1, SU2, SU3, SU4, and SU5 represent upshift lines, which are the vehicle speeds at which a gear shift occurs from a low gear to a top gear, and dotted lines SD1, SD2, SD3, SD4, and SD5 represent downshift lines, which are the vehicle speeds at which a gear shift occurs from a top gear to a low gear. In accordance with this gear shift schedule, the PCM 70 controls the hydraulic control valve 123 of the automatic transmission 101 to perform the required gear shifting operation.

[0060] The indications (1) to (5) in Figure 5 indicate the gear stages when upshifting. The leftmost SU1 is the upshift line from 1st to 2nd, SU2 is the upshift line from 2nd to 3rd, and the rightmost SU5 is the upshift line from 5th to 6th. On the other hand, the indications [1] to [5] in Figure 5 indicate the gear stages when downshifting. The rightmost SD5 is the downshift line from 6th to 5th, SD4 is the downshift line from 5th to 4th, and the leftmost SD1 is the downshift line from 2nd to 1st.

[0061] In this embodiment, the gear shift schedule is changed between normal operation and when an abnormality occurs in which compression leakage is detected in combustion chamber C. The upshift lines SU2 to SU5 and downshift lines SD2 to SD5 shown in Fig. 5 each have two branched regions: a thick line portion and a thin line portion. The thin line portion represents normal operation, and when an abnormality occurs, the thin line portion becomes the upshift line or downshift line changed to the thick line portion. In other words, when an abnormality in compression leakage occurs, the gear shift vehicle speed is changed from the thin line portion to the thick line portion, where the vehicle speed is higher.

[0062] Specifically, the thin line portion SU21 of the upshift line SU2 indicates the vehicle speed at which second gear changes to third gear during normal driving, and the thick line portion SU22 indicates the vehicle speed at which second gear changes to third gear when a compression leak abnormality occurs. Similarly, the thin line portions SU31, SU41, and SU51 of the upshift lines SU3, SU4, and SU5 indicate the vehicle speeds at which a gear is changed up during normal driving, and the thick line portions SU32, SU42, and SU52 indicate the vehicle speeds at which a gear is changed up when a compression leak abnormality occurs. Furthermore, the thin line portion SD21 of the downshift line SD2 indicates the vehicle speed at which third gear changes to second gear during normal driving, and the thick line portion SD22 indicates the vehicle speed at which third gear changes to second gear when a compression leak abnormality occurs. Similarly, the thin line portions SD31, SD41, and SD51 of the downshift lines SD3, SD4, and SD5 indicate the switching vehicle speeds when changing down a gear during normal driving, and the thick line portions SD32, SD42, and SD52 indicate the switching vehicle speeds when changing down a gear when an abnormality occurs.

[0063] An example of a change in the gear shift schedule will be shown below. For example, assume that acceleration is performed with an accelerator opening of 30% during normal driving. In this case, when the vehicle speed reaches 28 km / h, the normal driving upshift line SU21 is exceeded, so the PCM 70 controls the automatic transmission 101 to change the gear from second gear to third gear. Also, when decelerating, when the vehicle speed reaches 23 km / h, the normal driving downshift line SD21 is exceeded, so the gear is changed from third gear to second gear.

[0064] In contrast, when downshifting when an abnormality occurs, the downshift line SD2 is changed to the thick line portion SD22 on the high-speed side (switching vehicle speed = 33 km / h). In this case, at the point where vehicle speed V1 = 30 km / h, the range is third gear during normal driving, but when an abnormality occurs, it is shifted down to second gear. This makes it possible to maintain the rotation speed of the engine body 2 at a higher rotation speed than during normal driving. On the other hand, at the point where vehicle speed V2 = 35 km / h, it is set to third gear. This is because the engine rotation speed can be maintained at a relatively high rotation speed even in third gear. Changing the gear shift schedule in this way is effective in removing deposits that can cause compression leakage.

[0065] Meanwhile, in the manual mode described above, the PCM 70 executes control to change the gear position of the automatic transmission 101 in response to an operation received from the driver via the operating lever 71. However, when the gear position schedule change control described above is being executed to remove deposits, the PCM 70 executes manual mode prohibition control to prohibit a change in gear position of the automatic transmission 101 in the manual mode. This is to prevent a situation in which the gear position switching vehicle speed has been changed to a higher position by the gear position schedule change control from being reset by a manual operation of the gear position.

[0066] [Countermeasures against deposit adhesion] Deposits (foreign matter) may adhere to the valve seats of the intake valve 13 or the exhaust valve 14. For example, deposits adhering to the inner wall of the intake passage 30 may break off and flow downstream, becoming trapped between the head portion 13b of the intake valve 13 and the valve seat 11a. Alternatively, deposits flowing into the combustion chamber C may become trapped between the head portion 14b of the exhaust valve 14 and the valve seat 12a. This trapping, which occurs when deposits adhere to the valve seats 11a, 11b or the head portions 13b, 14b, can lead to compression leakage, a phenomenon in which compressed air leaks from the combustion chamber C through the intake port 11 or the exhaust port 12 during the compression stroke. When compression leakage occurs, the fuel-air mixture injected into the combustion chamber C may not burn properly, and even misfires may occur, resulting in poor ignition. Therefore, in this embodiment, as a countermeasure against deposits on the valve seats, the PCM 70 executes control as shown in FIG. 6. This control will be described in detail below.

[0067] 6 is a flowchart showing details of the control executed by the PCM 70 while the engine 1 is operating and the crankshaft 7 is rotating. When the control starts, the PCM 70 reads information output from each of the sensors SN1 to SN7 (step S1).

[0068] Next, the PCM 70 calculates a compression state index value V, which is an index value representing the compression state of the cylinder 2a (step S2). Specifically, the PCM 70 calculates the ratio (T1 / T2) of a first time T1 to a second time T2 shown in FIG. 7 as the compression state index value V. The first time T1 is the time required for the crankshaft 7 to pass through a first crank angle range ΔC1 that spans from the compression stroke to the expansion stroke. The second time T2 is the time required for the crankshaft 7 to pass through a second crank angle range ΔC2 that is included in the expansion stroke immediately following the compression stroke. The PCM 70 calculates the compression state index value V (=T1 / T2), which is a value obtained by dividing the former by the latter, for each combustion cycle of each cylinder 2a. The compression state index value V can be calculated based on input information from the crank angle sensor SN1.

[0069] The first crank angle range ΔC1 is set to a predetermined angle range including compression top dead center (TDC), which is the boundary between the compression stroke and the expansion stroke. The second crank angle range ΔC2 is set to a predetermined angle range separated from the first crank angle range ΔC1 on the retard side and included in the expansion stroke. The first crank angle range ΔC1 and the second crank angle range ΔC2 are set to have the same width (for example, a width of 30° CA) in FIG. 7.

[0070] The speed at which the piston 5 moves through the second crank angle range ΔC2 is faster than the speed at which the piston 5 moves through the first crank angle range ΔC1. This is because the compression reaction force acting on the piston 5 is maximized at compression top dead center and because an expansion force acts to accelerate the piston 5 during the expansion stroke. The fact that the speed at which the piston passes through the second crank angle range ΔC2 is faster than the speed at which the piston passes through the first crank angle range ΔC1 means that the second time T2, which is the time it takes to pass through the second crank angle range ΔC2, is shorter than the first time T1, which is the time it takes to pass through the first crank angle range ΔC1. Therefore, the compression state index value V, calculated as T1 / T2 as described above, is usually calculated as a value significantly greater than 1.

[0071] However, if compressed air leaks from the combustion chamber C through the intake port 11 or the exhaust port 12 during the compression stroke, that is, if compression leakage occurs, the compression reaction force acting on the piston 5 during the compression stroke becomes smaller, so the difference between the first time T1 and the second time T2 decreases. This means that the compression state index value V = T1 / T2 approaches 1. In other words, the compression state index value V is a parameter that varies depending on the presence or absence of compression leakage. The PCM 70 estimates the compression state (the presence or absence of compression leakage) of each cylinder 2a by calculating the compression state index value V having such a property for each combustion cycle of each cylinder 2a. Thus, in the present embodiment, the compression state index value V is calculated by the PCM 70 based on the input information from the crank angle sensor SN1. Therefore, the combination of the crank angle sensor SN1 and the PCM 70 corresponds to the "compression leakage detection unit" in the present invention.

[0072] Subsequently, the PCM 70 determines whether or not a deposit is attached to the valve seat portion based on the calculated compression state index value V (step S3). Specifically, the PCM 70 compares the compression state index value V with a predetermined threshold value Vx for each combustion cycle of each cylinder 2a, and determines whether the former is less than the latter, that is, whether V<Vx holds. When the state where V<Vx holds occurs continuously for a predetermined number of cycles n1 for the same cylinder 2a, the PCM 70 determines that a deposit is attached to the valve seat portion of the cylinder 2a. The continuous cycle number n1 can be set to, for example, "2". Note that the valve seat portion is between the intake valve 13 and the valve seat 11a, or between the exhaust valve 14 and the valve seat 12a.

[0073] The threshold value Vx used in the determination of step S3 is determined from the average value of the compression state index values V of all the cylinders 2a calculated one cycle before. That the compression state index value V of a specific cylinder 2a is smaller than the threshold value Vx means that there is a high possibility that compression leakage has occurred in the specific cylinder 2a. That is, it means that there is a high possibility that compressed air is leaking from the combustion chamber C due to deposits adhering to the valve seat portion of the specific cylinder 2a. Therefore, when the state of V<Vx described above occurs continuously for n1 cycles in the same cylinder 2a, the PCM 70 determines that deposits are adhering to the cylinder 2a.

[0074] When it is confirmed that no deposits are adhering to the valve seat portion of any of the cylinders 2a (NO in step S3), the PCM 70 executes normal engine control (step S11). Here, since no deposit countermeasures are required, the controls corresponding to steps S6, S7, S9, S10, S13, and S14 described later are not executed.

[0075] On the other hand, when it is confirmed that deposits are adhering to the valve seat portion of any of the cylinders 2a (YES in step S3), the PCM 70 determines whether or not the engine 1 is in deceleration fuel cut (step S4). Deceleration fuel cut is an operation mode in which fuel injection from the fuel injection valve 9 is stopped during deceleration of the vehicle, or in other words, an operation mode in which the rotation of the crankshaft 7 is maintained by using the rotation of the wheel W1. Deceleration fuel cut is permitted, for example, when all of the conditions that the accelerator opening is zero, the vehicle speed is higher than a predetermined reference speed, and the engine speed is higher than a predetermined reference speed are satisfied. The PCM 70 determines whether or not the permission conditions for such deceleration fuel cut are satisfied based on the input information from the crank angle sensor SN1, the accelerator sensor SN5, and the vehicle speed sensor SN6, and executes deceleration fuel cut when the conditions are satisfied.

[0076] If it is determined that deceleration fuel cut is being performed (YES in step S4), the PCM 70 changes the opening degree of the intake shutter valve 33 to a value larger than normal (step S5). During normal deceleration fuel cut operation, the opening degree of the intake shutter valve 33 is set to a relatively small value for the purpose of applying engine braking, etc. In contrast, in step S5, the intake shutter valve 33 is controlled so that the opening degree of the intake shutter valve 33 is set to a value larger than the opening degree during normal deceleration fuel cut. This is to increase the in-cylinder pressure, which is the internal pressure of the cylinder 2a (combustion chamber C), and increase the possibility that deposits adhering to the valve seat portion will be crushed.

[0077] On the other hand, if it is confirmed that deceleration fuel cut is not being performed (NO in step S4), the PCM 70 executes suppression control to suppress a decrease in engine speed. First, as one of the suppression controls, the PCM 70 prohibits idle stop control of the engine 1 (step S6). Idle stop is a control that automatically stops the engine 1 when predetermined idle stop conditions are met, such as when the vehicle speed is zero and the accelerator opening is zero. In step S6, the PCM 70 turns on the idle stop prohibition flag so that the engine 1 is not automatically stopped even when the idle stop conditions are met. This is to prevent failure of restarting the engine 1 due to deposit buildup.

[0078] Next, as another type of suppression control, the PCM 70 executes idle speed increase control, which sets the idle speed of the engine 1 to a higher speed than normal (step S7). Increasing the idle speed increases the rotational inertia of the engine 1 during idle operation. This makes it less likely for the engine to stall even if the engine is switched to idle operation with deposits still present.

[0079] Next, the PCM 70 determines whether the engine speed is equal to or less than a predetermined threshold value Nx based on input information from the crank angle sensor SN1 (step S8). The threshold value Nx is set to an appropriate value higher than the idle speed after the increase in step S7. For example, the threshold value Nx can be set to approximately 1200 rpm.

[0080] If it is determined that the engine speed is equal to or lower than the threshold value Nx (YES in step S8), more rigorous deposit removal measures are taken. In this case, the PCM 70 changes the opening of the EGR valve 53 to a value smaller than normal (step S9). During combustion operation of the engine 1, the opening of the EGR valve 53 is normally controlled so that an appropriate amount of EGR gas depending on the operating conditions is introduced into the combustion chamber C of each cylinder 2a, for the purpose of reducing the amount of NOx generated by combustion. In contrast, in step S9, the EGR valve 53 is controlled so that the opening of the EGR valve 53 is reduced to a value smaller than the normal opening determined depending on the operating conditions. The reduced opening of the EGR valve 53 may be set to an appropriate value within a range in which the amount of recirculation of EGR gas is reduced compared to normal. Note that the opening of the EGR valve 53 may also be reduced to an opening equivalent to a fully closed position, at which the recirculation of EGR gas is substantially stopped. By restricting the EGR gas, the amount of intake air supplied through the second turbine 62b increases, increasing the intake pressure and making it easier to remove deposits.

[0081] Next, the PCM 70 changes the amount of fuel injected by the fuel injector 9 to a value greater than normal (step S10). During normal operation, the fuel injector 9 of each cylinder 2a is controlled so that an appropriate amount of fuel corresponding to the required torque of the engine 1, which is determined based on the accelerator pedal position, vehicle speed, etc., is supplied to the combustion chamber C of each cylinder 2a. In contrast, in step S10, the fuel injector 9 is controlled so that more fuel is injected than the normal injection amount determined based on the required torque. Note that this control to increase the injection amount may be performed at least on the fuel injector 9 of the cylinder 2a for which deposits have been confirmed in the determination of step S3, but it is also possible to increase the injection amount of the fuel injector 9 of all cylinders 2a. By increasing the fuel injection amount, it is possible to burn off the deposits.

[0082] Next, the control when the engine speed is greater than the threshold value Nx (NO in step S8) will be described. In this case, the PCM 70 determines whether the deposit adhesion continues (step S12). For the cylinder 2a where deposit adhesion was determined in step S3, the PCM 70 determines whether a state where the compression state index value V is less than the threshold value Vx (V<Vx) has occurred continuously for a further predetermined number of cycles n2. After the deposit adhesion is determined, the fact that the state of V<Vx has occurred continuously for a further n2 cycles means that compression leakage has occurred continuously for n1 + n2 cycles for the same cylinder 2a, which means that it is highly likely that the deposit has not been removed yet. Note that the continuous cycle number n2 here is preferably larger than the continuous cycle number n1 used in the determination in step S3. For example, the continuous cycle number n2 can be set to "5".

[0083] When it is determined NO in step S14 and it is confirmed that the deposit adhesion does not continue (NO in step S12), the PCM 70 executes normal shift control for the automatic transmission 101 (step S17). Here, since deposit countermeasures are not required, the controls corresponding to steps S13 and S14 described later are not executed.

[0084] On the other hand, when compression leakage is still detected after the execution of the control for suppressing the decrease in the engine speed in steps S6 and S7, that is, when continuous deposit adhesion is confirmed (YES in step S12), the PCM 70 executes shift schedule change control, lock-up speed reduction control, and manual mode prohibition control.

[0085] Specifically, as illustrated in FIG. 5, the PCM 70 executes gear shift schedule change control to change the gear shift speed set in the gear shift schedule to a higher speed (step S13). The gear shift schedule change control can change the gear shift speed applied at a certain vehicle speed to a lower speed than that during normal driving when a compression leak is detected. As illustrated in FIG. 5, for example, at a point where the accelerator opening is less than approximately 35% and the vehicle speed V1 is 30 km / h, the shift speed from third gear to second gear is changed to a higher speed from the normal downshift line SD21 to SD22. In other words, while third gear is set during normal driving, second gear is set when a compression leak is detected. This expands the range in which the engine speed is maintained at a high speed, increasing the possibility of deposit removal by the high-speed operation of the intake valve 13 or exhaust valve 14 itself.

[0086] Next, the PCM 70 executes control to reduce the lockup speed. The PCM 70 changes the lockup release speed so that the lockup region, which is the range of engine speeds at which lockup clutch 115 is engaged, expands toward lower engine speeds (step S14). That is, the PCM 70 changes the lockup release speed, which is the engine speed at which lockup clutch 115 is released during deceleration, to a value lower than normal. This expands the lockup region toward lower engine speeds, and the locked-up state is maintained down to engine speeds lower than normal. This control to reduce the lockup speed expands the region in which crankshaft 7 rotates in synchronization with drive wheels W1, thereby increasing the possibility of deposit removal by the operation of intake valve 13 or exhaust valve 14 itself.

[0087] Figures 8 and 9 are charts showing the relationship between engine speed, gear position, and lockup release speed, with Figure 8 being the chart during normal driving and Figure 9 being the chart when a compression leakage abnormality is detected. First, referring to Figure 8, it is assumed that the lockup release speed (vehicle speed) during normal driving is set to LR1 (e.g., 25 km / h), the downshift switch vehicle speed from third gear to second gear is set to SD21 (23 km / h), and the downshift switch vehicle speed from second gear to first gear is set to SD1 (7 km / h).

[0088] In this case, when the vehicle speed becomes slower than LR1, the lockup is released. In other words, the lockup clutch 115 is released, and the crankshaft 7 and the turbine shaft 114 of the automatic transmission 101 are disconnected. As a result, the rotation of the wheel W1 is not directly transmitted to the crankshaft 7, and the engine speed remains constant at the idle speed in the speed range slower than LR1. When the shift speeds SD21 and SD1 are reached, where the gears are shifted from third gear to second gear and from second gear to first gear, the rotation speed of the turbine shaft 114 increases, but this is not reflected in the engine speed.

[0089] In contrast, suppose that a compression leakage abnormality is detected at a vehicle speed at time t1 during a downshift. Then, suppose that the flow of FIG. 6 is executed, and the actions of steps S13 and S14 are performed. Referring to FIG. 9, when a compression leakage abnormality is detected, the shift speed from third gear to second gear is changed from the normal SD21 to SD22 (33 km / h), a higher speed, by the gear stage schedule change control, as described above. Furthermore, the lockup release rotation speed (vehicle speed) is changed from LR1 to LR2 (e.g., 16 km / h) by the lockup rotation speed reduction control.

[0090] In this case, the lockup is not released even if the vehicle speed drops below LR1. On the other hand, when the vehicle speed drops to SD22, the automatic transmission 101 shifts from third gear to second gear. This shift to a lower gear allows the engine speed to be maintained at a speed higher than that suitable for deposit removal (for example, 1500 rpm). In other words, because the lockup is not released, the rotation of the wheel W1 is transmitted directly to the crankshaft 7, so the engine speed can be increased by shifting down. This can therefore improve the deposit removal effect.

[0091] Next, the PCM 70 determines whether or not the manual mode is selected based on the detection result of the shift position sensor SN7 (step S15). When the manual mode is selected, the driver can freely change the gear position of the automatic transmission 101 through the operation lever 71. However, if the driver applies the manual mode and changes the gear position while the gear position schedule change control of step S13 is being executed, the effect of maintaining the engine speed at a high speed may be lost, and the deposit removal effect may be reduced.

[0092] Therefore, when the gear stage schedule change control of step S13 is being executed, even if the manual mode is selected, manual mode prohibition control is executed to prohibit changing the gear stage of the automatic transmission 101 in the manual mode. That is, when the manual mode is selected (YES in step S15), the PCM 70 prohibits manual operation of the gear stage of the automatic transmission 101 via the operation lever 71 (step S16). Execution of the manual mode prohibition control allows the gear stage schedule change control to satisfactorily achieve the deposit removal effect that is originally expected from the gear stage schedule change control.

[0093] When the manual mode prohibition control is executed, the PCM 70 displays information on the display unit 72 indicating that shifting of the automatic transmission 101 in the manual mode is prohibited (step S17). The displayed information may be a message such as "Manual shifting is currently not possible," or an indicator indicating that manual operation is prohibited is illuminated. This display can notify the driver that the manual mode prohibition control is being executed. This can encourage the driver to avoid using the manual mode or can help the driver recognize the cause of a malfunction in manual operation and prevent distrust.

[0094] [Variations] Although the embodiments of the present invention have been described above, the present invention is not limited to these and can take the following modified embodiments, for example.

[0095] (1) In the above embodiment, after a compression leak is detected (YES in step S3), suppression control (steps S6 and S7) is executed to suppress a decrease in engine speed, and if a compression leak is still detected after the suppression control is executed (YES in step S12), the gear stage schedule change control, lockup speed reduction control, and manual mode prohibition control in steps S13, S14, and S16 are executed. Alternatively, steps S13, S14, and S16 may be executed immediately after a compression leak is detected in step S3.

[0096] (2) In the above embodiment, the compression state index value V representing the compression state of cylinder 2a was calculated as the ratio (T1 / T2) of the first time T1 required for the cylinder to pass through a first crank angle range ΔC1 that spans the compression top dead center to the second time T2 required for the cylinder to pass through a second crank angle range ΔC2 that is included in the expansion stroke. The compression state index value V may be any value that varies depending on the presence or absence of compression leakage, and various modifications are possible within that range. For example, the difference between the first time T1 and the second time T2 may be used as the compression state index value V. Furthermore, the first time T1 may be the time required for the cylinder to pass through a predetermined crank angle range that is more advanced than ΔC1 in FIG. 7 and is included in the compression stroke, and the second time T2 may be the time required for the cylinder to pass through a predetermined crank angle range that is more advanced or retarded than ΔC2 in FIG. 6 and is included in the expansion stroke. Furthermore, the average moving speed of the piston 5 may be calculated from the time required to pass through a specific crank angle range in each of the compression stroke and the expansion stroke, and the ratio of the two speeds may be used as the compression state index value V.

[0097] (3) In the above embodiment, compression leakage is detected based on the compression state index value V calculated by the PCM 70 from the input information of the crank angle sensor SN1. However, the means for detecting compression leakage is not limited to this. For example, an in-cylinder pressure sensor may be provided to detect the in-cylinder pressure, which is the internal pressure of the cylinder 2a (combustion chamber C), and compression leakage may be detected based on the detected value of the in-cylinder pressure sensor.

[0098] (4) In the above embodiment, an example was shown in which both the gear stage schedule change control in step S13 and the lockup rotation speed reduction control in step S14 were executed. Instead of this, only the gear stage schedule change control may be executed. [Explanation of symbols]

[0099] 1 engine 2 Engine body 11 Intake port 12 Exhaust port 13 Intake valve 14 Exhaust valve 30 intake passage 40 Exhaust passage 70 PCM70 (control unit / compression leak detection unit) 71 Operating lever 72 Display section 101 Automatic Transmission C. Combustion chamber SN1 Crank angle sensor (compression leak detection part)

Claims

1. A control device for an automatic transmission connected to an engine including a combustion chamber, an intake passage connected to the combustion chamber via an intake port, an exhaust passage connected to the combustion chamber via an exhaust port, and an intake valve and an exhaust valve that open and close the intake port and the exhaust port, an operation lever that accepts a selection operation of a manual mode and an operation of a gear position of the automatic transmission in the manual mode from a driver; a control unit that controls the gear positions of the automatic transmission in accordance with a preset gear position schedule and changes the gear positions of the automatic transmission in response to an operation received by the operating lever in the manual mode; a compression leakage detection unit that detects a compression leakage, which is a phenomenon in which air leaks from the combustion chamber through the intake port or the exhaust port during a compression stroke, The control unit a gear shift schedule change control that changes a gear shift vehicle speed set in the gear shift schedule to a higher speed when a compression leak is detected by the compression leak detection unit; a manual mode prohibition control that prohibits a change of the gear position of the automatic transmission in the manual mode even if the manual mode is selected when the gear position schedule change control is executed; A control device for an automatic transmission that performs the above.

2. 2. The automatic transmission control device according to claim 1, Further, a display unit is provided to display information for the driver, When the control unit executes the manual mode prohibition control, the control unit causes the display unit to display information indicating that operation of the gear position of the automatic transmission in the manual mode is prohibited.

3. 3. The automatic transmission control device according to claim 1, The control unit is a control device for an automatic transmission that, when executing the gear stage schedule change control, changes the engine speed to a lower speed, which releases lockup, a state in which the engine output is directly transmitted to the drive wheels via the automatic transmission.

4. The automatic transmission control device according to any one of claims 1 to 3, The control unit When the compression leakage detection unit detects a compression leakage, the control unit executes a suppression control to suppress a decrease in engine rotation speed. A control device for an automatic transmission that, when the compression leakage is still detected after the suppression control is executed, executes the gear stage schedule change control and the manual mode prohibition control.

5. 5. The automatic transmission control device according to claim 4, The control device for an automatic transmission, wherein the inhibiting control is a prohibition of an idle stop control that stops the engine when a predetermined idle stop condition is met, or an idle speed increase control that sets the idle speed of the engine to a higher speed than normal.

Images