Control device for engine system

Abstract

To provide a control device for an engine system that can suppress inflow of oil into an oil tank at a stop of an engine with a simple structure.SOLUTION: A control device for an engine system that comprises: an engine with a throttle valve arranged on an intake pipe; an oil tank storing lubrication oil for the engine; first piping to feed oil and blow-by gas from the engine to the oil tank; and second piping to feed blow-by gas from the oil tank to a portion downstream from the throttle valve of the intake pipe. The control device for the engine system comprises: an execution unit for, when there is a stop request for the engine, executing a negative pressure alleviation operation, which alleviates negative pressure in the oil tank by continuing the rotation of the engine with an increased opening of the throttle valve relative to that of the throttle valve immediately before the stop request; and a stop unit for stopping the rotation of the engine after the execution of the negative pressure alleviation operation.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a control device for an engine system. [Background technology]

[0002] When the engine is stopped, the pressure in the oil tank may become negative, causing oil to flow into the oil tank. In order to prevent oil from flowing into the oil tank when the engine is stopped, there is a technique for supplying gas into the oil tank when the engine is stopped to eliminate the negative pressure in the oil tank (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2018-044448 A Summary of the Invention [Problem to be solved by the invention]

[0004] The above technology requires the installation of new piping for supplying gas into the oil tank and new valves for opening and closing the piping, which makes the structure more complicated.

[0005] SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to provide an engine system control device that has a simple structure and is capable of suppressing the inflow of oil into an oil tank when the engine is stopped. [Means for solving the problem]

[0006] The above object can be achieved by a control device for an engine system including an engine having an engine with a throttle valve provided in an intake pipe, an oil tank for storing oil for lubricating the engine, a first piping for flowing oil and blow-by gas from the engine to the oil tank, and a second piping for flowing blow-by gas from the oil tank to a portion of the intake pipe downstream of the throttle valve, the control device for the engine system including: an execution unit that, when a request to stop the engine is made, executes a negative pressure reduction operation to reduce the negative pressure in the oil tank by increasing the opening of the throttle valve more than the opening of the throttle valve immediately before the stop request and continuing the rotation of the engine; and a stopping unit that stops the rotation of the engine after the negative pressure reduction operation is executed. Effect of the Invention

[0007] According to the present invention, it is possible to provide a control device for an engine system that has a simple structure and is capable of suppressing the inflow of oil into an oil tank when the engine is stopped. [Brief description of the drawings]

[0008] [Figure 1] FIG. 2 is a schematic configuration diagram of an engine system. [Diagram 2] 4 is a flowchart showing an example of engine stop control executed by the ECU. [Diagram 3] 10 is a flowchart showing a modified example of the engine stop control. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] FIG. 1 is a schematic diagram of an engine system A. The engine system A is mounted on, for example, an engine vehicle. The engine system A includes an engine 1, an oil tank 7, and an ECU (Electronic Control Unit) 20. The engine 1 includes a pair of banks 2L and 2R and a cylinder block 3. That is, the engine 1 is a so-called V-type engine, but may also be an in-line engine. Furthermore, the engine 1 is a gasoline engine, but may also be a diesel engine. A crankshaft 3a is rotatably provided in the cylinder block 3.

[0010] Each of the banks 2L and 2R has a plurality of cylinders. An intake pipe 4L is connected to the bank 2L via an intake manifold 5L. An intake pipe 4R is connected to the bank 2R via an intake manifold 5R. A throttle valve 6L is provided in the intake pipe 4R. An exhaust passage is connected to each of the pair of banks 2L and 2R via an exhaust manifold (not shown).

[0011] The ECU 20 is mainly composed of a computer including a CPU (Central Processing Unit), and volatile and non-volatile memories such as RAM (Random Access Memory) and ROM (Read Only Memory). The ECU 20 is an example of a control device for the engine system A. The ECU 20 functionally realizes an execution unit and a stop unit, which will be described in detail later.

[0012] An ignition switch S1 and a pressure sensor S2 are connected to the ECU 20. The ignition switch S1 detects the on / off state of the ignition. The pressure sensor S2 detects the pressure in the space filled with gas in the oil tank 7, which will be described in detail later. The ECU 20 also adjusts the opening of the throttle valves 6L and 6R according to the operating state of the engine 1. The display unit 21 is controlled by the ECU 20 and is provided on the instrument panel of the vehicle.

[0013] The oil tank 7 is a dry sump tank that stores oil for lubricating the engine 1. The oil tank 7 is connected to the cylinder block 3 of the engine 1 via an oil pipe 11. When the scavenging pump P is driven, the oil used in the engine 1 flows into the oil tank 7 via the oil pipe 11. In addition, blow-by gas generated in the engine 1 also flows into the oil tank 7 via the oil pipe 11. The scavenging pump P is a mechanical oil pump that is driven in conjunction with the rotation of the crankshaft 3a of the engine 1. The oil pipe 11 is an example of a first pipe that flows oil from the engine 1 to the oil tank 7. The oil stored in the oil tank 7 is pressure-fed to the lubrication parts of the engine 1 by a feed pump (not shown).

[0014] An oil separator 8 is provided on the upper part of the oil tank 7. The oil separator 8 separates oil from the blow-by gas introduced into the oil tank 7. The oil separated from the blow-by gas is stored in the oil tank 7. The oil separator 8 is provided with two check valves 9L and 9R. The blow-by gas pipe 12L connects the oil separator 8 to the intake manifold 5L via the check valve 9L. The blow-by gas pipe 12R connects the oil separator 8 to the intake manifold 5R via the check valve 9R. The check valve 9L allows gas to flow from the oil separator 8 to the intake manifold 5L, but restricts gas to flow from the intake manifold 5L to the oil separator 8. The check valve 9R allows gas to flow from the oil separator 8 to the intake manifold 5R, but restricts gas to flow from the intake manifold 5R to the oil separator 8.

[0015] When the check valve 9L opens, the blow-by gas in the oil separator 8 is supplied to the intake manifold 5L via the blow-by gas pipe 12L. When the check valve 9R opens, the blow-by gas in the oil separator 8 is supplied to the intake manifold 5R via the blow-by gas pipe 12R. This allows the blow-by gas to be used for combustion in the engine 1. The blow-by gas pipe 12L is an example of a second pipe that allows the blow-by gas to flow from the oil tank 7 to a portion downstream of the throttle valve 6L in the intake pipe 4L. The blow-by gas pipe 12R is an example of a second pipe that allows the blow-by gas to flow from the oil tank 7 to a portion downstream of the throttle valve 6R in the intake pipe 4R.

[0016] In this way, the oil used in the engine 1 is recovered by the scavenging pump P, the oil piping 11, and the oil tank 7. In addition, the blow-by gas generated within the engine 1 is returned to the engine 1 by the scavenging pump P, the oil piping 11, the oil tank 7, the oil separator 8, and the blow-by gas piping 12L and 12R. Therefore, these mechanisms are mechanisms for achieving the recovery of oil and the return of blow-by gas.

[0017] When there is a request to stop the engine 1, the operation state of the engine 1 is an idle operation state. Therefore, the opening degree of each of the throttle valves 6L and 6R is relatively small. Therefore, the pressure in the intake manifolds 5L and 5R is negative. Accordingly, the pressure in the oil tank 7, which is connected to the intake manifolds 5L and 5R via the blow-by gas pipes 12L and 12R, respectively, is also negative. When the engine 1 is stopped in this state, the negative pressure in the oil tank 7 may cause oil to flow into the oil tank 7 from the cylinder block 3 through the oil pipe 11. If oil flows into the oil tank 7 when the engine 1 is stopped, an oil inflow sound may be generated, which may cause a driver to feel uncomfortable. In this embodiment, the ECU 20 executes the following engine stop control. As a result, the inflow of oil into the oil tank 7 when the engine 1 is stopped is suppressed.

[0018] [Engine stop control] 2 is a flowchart showing an example of engine stop control executed by the ECU 20. This control is repeatedly executed while the ignition is on. The ECU 20 determines whether or not there is an engine stop request based on, for example, the on / off state of the ignition switch S1 (step S1). If the answer is No in step S1, this control ends.

[0019] If the result in step S1 is Yes, the ECU 20 determines whether the pressure in the oil tank 7 is equal to or lower than a threshold value based on the detection value of the pressure sensor S2 (step S2). The threshold value is set to a negative pressure value at which oil flows into the oil tank 7 through the oil piping 11 when the engine 1 is stopped. That is, the ECU 20 determines whether oil flows into the oil tank 7 when the engine 1 is stopped.

[0020] If the answer is Yes in step S2, the ECU 20 executes a negative pressure reduction operation (step S3). The negative pressure reduction operation is an operation of the engine 1 for reducing the negative pressure in the oil tank 7. Specifically, the ECU 20 increases the opening degree of each of the throttle valves 6L and 6R from the opening degree immediately before a request to stop the engine 1 is made, and allows the engine 1 to continue rotating. By increasing the opening degree of each of the throttle valves 6L and 6R, the negative pressure in the intake manifolds 5L and 5R is reduced. Accordingly, the negative pressure in the oil tank 7, which is connected to the intake manifolds 5L and 5R via the blow-by gas pipes 12L and 12R, respectively, is also reduced. Step S3 is an example of a process executed by the execution unit.

[0021] In order to quickly reduce the negative pressure in the oil tank 7, it is preferable that the openings of the throttle valves 6L and 6R during the negative pressure reduction operation are maximum. However, if these openings are too large, the amount of intake air increases, which may increase the rotation speed of the engine 1 and increase the driving noise. Therefore, it is preferable to determine the openings of the throttle valves 6L and 6R during the negative pressure reduction operation by taking into consideration the speed at which the negative pressure is reduced and the increase in the driving noise of the engine 1. For example, the openings of the throttle valves 6L and 6R during the negative pressure reduction operation may be set to the openings during cold fast idle operation, which promotes the warm-up of the engine 1 during cold start.

[0022] Next, the ECU 20 notifies the driver that the negative pressure reduction operation is being performed (step S4). Specifically, the ECU 20 causes the display unit 21 to display that the negative pressure reduction operation is being performed. This can alleviate the driver's anxiety about the continued operation of the engine 1. The method of notification is not limited to this. For example, the above notification may be made by sound through a speaker of the vehicle's audio system, navigation system, or the like.

[0023] Next, the ECU 20 executes step S2 again. If the result of step S2 is No, the ECU 20 stops fuel injection in the engine 1 to stop the engine 1 (step S5). Step S5 is an example of a process executed by the stopping unit.

[0024] As described above, by performing the negative pressure reduction operation, the mechanism for recovering oil and returning blow-by gas can be used to suppress the inflow of oil into the oil tank 7. Therefore, without providing new piping or valves, the inflow of oil into the oil tank 7 when the engine 1 is stopped can be suppressed with a simple structure.

[0025] [Variations] In the above embodiment, the engine system A is installed in an internal combustion engine vehicle. In this modified example, engine stop control will be described for a hybrid vehicle equipped with the engine system A. A hybrid vehicle includes an engine 1 and a motor (not shown), and the crankshaft 3a can be rotated by the motor.

[0026] 3 is a flowchart showing a modified example of the engine stop control. In the engine stop control of this modified example, the same processes as those in the above-mentioned embodiment are designated by the same reference numerals and will not be described again. The ECU 20 determines whether or not there is an engine stop request based on whether or not a ready-off signal has been received (step S1a).

[0027] If the answer is Yes in step S2, the ECU 20 executes the negative pressure reduction operation (step S3a). In the negative pressure reduction operation in this modification, the opening degree of each of the throttle valves 6L and 6R is increased from the opening degree immediately before the stop request of the engine 1 is made, fuel injection in the engine 1 is stopped, and the engine 1 continues to rotate by the motor. This makes it possible to control the rotation speed of the engine 1 independently of the opening degree of each of the throttle valves 6L and 6R. For example, fuel injection in the engine 1 can be stopped while the rotation speed of the engine 1 is maintained at an idle rotation speed by the motor. This makes it possible to execute the negative pressure reduction operation without causing a large change in the rotation speed from the rotation speed immediately before the stop request of the engine 1 is made. This makes it possible to avoid giving a sense of discomfort to the driver due to a change in the rotation speed of the engine 1. After that, if the answer is No in step S2, the ECU 20 stops the rotation of the engine 1 by stopping the motor (step S5a).

[0028] In the above embodiment and modified example, the pressure sensor S2 detects the pressure in the oil tank 7, but is not limited to this. For example, the pressure sensor S2 may detect the pressure downstream of the throttle valve 6L or the pressure downstream of the throttle valve 6R. This is because these pressures are correlated with the pressure in the oil tank 7.

[0029] Although the embodiments of the present invention have been described in detail above, the present invention is not limited to such specific embodiments, and various modifications and variations are possible within the scope of the gist of the present invention described in the claims. [Explanation of symbols]

[0030] A. Engine system 1 Engine 4L, 4R intake pipe 6L, 6R throttle valve 7. Oil Tank 11 Oil piping (first piping) 12L, 12R Blow-by gas piping (second piping) 20 ECU (control unit)

Claims

[Claim 1] An engine having a throttle valve provided in an intake pipe; an oil tank that stores oil for lubricating the engine; a first pipe for passing oil and blow-by gas from the engine to the oil tank; a second pipe for allowing blow-by gas to flow from the oil tank to a portion of the intake pipe downstream of the throttle valve; A control device for an engine system comprising: an execution unit that, when a request to stop the engine is received, executes a negative pressure reduction operation to reduce the negative pressure in the oil tank by increasing an opening degree of the throttle valve to a value greater than the opening degree of the throttle valve immediately before the request to stop the engine and continuing the rotation of the engine; a stop unit that stops rotation of the engine after the negative pressure reduction operation is performed.

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