Engine control device

Abstract

To provide an engine control apparatus capable of accelerating warm-up of piston while securing engine lubrication performance.SOLUTION: An engine control apparatus, which allows a lubricant to circulate through an engine in operation, the engine that includes an oil jet that jets the lubricant toward a piston, includes: a lubrication completion determination part for determining whether lubrication of the engine is completed while the engine is in the last operation before starting the engine is requested; a lubrication maintaining determination part for determining whether the engine lubrication is maintained when the starting the engine has been requested; and an execution part for executing injection suppression processing to suppress injection jetting of the lubricant from the oil jet while circulating the lubricant in the engine by starting the engine in a case where the lubrication completion determination part and lubrication maintaining determination part have made positive determination.SELECTED DRAWING: Figure 3

Description

[Technical Field]

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

[0002] By controlling the pressure of the lubricating oil circulating in the engine to be high when the engine is started, the engine can be lubricated early (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-138831 Summary of the Invention [Problem to be solved by the invention]

[0004] Some engines are equipped with oil jets that inject lubricating oil toward the pistons. In this case, the injection of lubricating oil from the oil jets at engine start-up can impair the warm-up of the pistons and cause deterioration of exhaust emissions. At the same time, it is necessary to ensure engine lubrication.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an engine control device that can promote warm-up of the pistons while ensuring lubrication of the engine. [Means for solving the problem]

[0006] The above object can be achieved by an engine control device in which lubricating oil circulates through an engine equipped with an oil jet that injects lubricating oil toward a piston while the engine is running, the engine control device comprising: a lubrication completion determination unit that determines whether lubrication of the engine was completed during the previous operation of the engine before a request to start the engine was made; a lubrication maintenance determination unit that determines whether the lubrication of the engine is maintained when the start request is made; and an execution unit that, when a positive determination is made by the lubrication completion determination unit and the lubrication maintenance determination unit, starts the engine and circulates lubricating oil through the engine while executing an injection suppression process that suppresses the spray of lubricating oil from the oil jet.

[0007] The lubrication completion determination unit may determine that lubrication of the engine has been completed when an accumulated intake air amount, which is an accumulated value of the intake air amount of the engine during the previous operation of the engine before the start request is made, is equal to or greater than a first threshold value, and the lubrication maintenance determination unit may determine that lubrication of the engine is maintained when the engine is stopped for a period of time from when the engine is stopped until the start request is made is less than a second threshold value.

[0008] The lubrication completion determination unit may determine that lubrication of the engine has been completed when an integrated rotation speed, which is an integrated value of the rotation speed of the engine during the previous operation of the engine before the start request is made, is equal to or greater than a first threshold value, and the lubrication maintenance determination unit may determine that lubrication of the engine is maintained when the engine is stopped for a period of time from when the engine is stopped until the start request is made is less than a second threshold value.

[0009] The lubrication completion determination unit may change the first threshold value to a smaller value as the temperature of the lubricating oil increases.

[0010] The injection suppression process may be a process of reducing the pressure of the lubricating oil when a positive judgment is made by the lubrication completion judgment unit and the lubrication maintenance judgment unit, more than when a negative judgment is made by at least one of the lubrication completion judgment unit and the lubrication maintenance judgment unit. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide an engine control device that can promote warm-up of the pistons while ensuring lubrication of the engine. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a schematic diagram of the engine. [Figure 2] FIG. 2 is an explanatory diagram of the distribution path of the lubricating oil. [Figure 3] FIG. 3 is a flowchart showing an example of piston warm-up control executed by the ECU. [Figure 4] FIG. 4 is a graph showing the temperature change of the piston with and without the injection of lubricating oil from the oil jet. [Figure 5] FIG. 5 is a timing chart showing an example of piston warm-up control. [Figure 6] FIG. 6 is an example of a map that defines the first threshold value. DETAILED DESCRIPTION OF THE INVENTION

[0013] [Engine outline] 1 is a schematic diagram of an engine 10. The engine 10 is mounted on an engine vehicle as a driving source, but is not limited to this. The engine 10 is a gasoline engine, but is not limited to this and may be a diesel engine. The engine 10 includes a cylinder head 11a, a cylinder block 11b provided below the cylinder head 11a, and an oil pan 11c provided below the cylinder block 11b.

[0014] Each cylinder 12 of the cylinder block 11b is provided with a piston 13. The piston 13 is connected to a crankshaft 15, which is the output shaft of the engine 10, via a connecting rod 14. The reciprocating motion of the piston 13 is converted into the rotational motion of the crankshaft 15 by the connecting rod 14.

[0015] The cylinder block 11b is provided with an oil jet 26. The oil jet 26 injects a portion of the lubricating oil pumped up from the oil pan 11c by an oil pump 52 (described later) toward the back surface of the piston 13. This promotes lubrication between the piston 13 and the inner wall surface of the cylinder bore of the cylinder 12. The oil jet 26 is provided with an on-off valve that opens and closes in response to the pressure of the lubricating oil.

[0016] A combustion chamber 16 is formed in the cylinder head 11a above the piston 13, and a spark plug 18 that ignites a mixture of fuel and air is attached to this combustion chamber 16. The timing at which the spark plug 18 ignites the mixture is adjusted by an igniter 19 provided above the spark plug 18. Lubricating oil is stored in the oil pan 11c.

[0017] The cylinder head 11a is provided with an intake valve 24 that opens and closes the intake passage 20 and the combustion chamber 16, and similarly, an exhaust valve 25 that opens and closes the exhaust passage 21 and the combustion chamber 16. The intake passage 20 is provided with a throttle valve 23 that adjusts the amount of air introduced into the combustion chamber 16.

[0018] Each intake port 20a constituting a part of the intake passage 20 is provided with a port injection valve 22 for injecting fuel into the intake port 20a for each cylinder 12. The engine 10 is also provided with an in-cylinder injection valve 17 for injecting fuel into each combustion chamber 16.

[0019] In the exhaust passage 21, a three-way catalyst 41 and a GPF (Gasoline Particulate Filter) 42 are provided in this order from the upstream side. The three-way catalyst 41 contains catalytic metals such as platinum (Pt), palladium (Pd), and rhodium (Rh), has oxygen storage capacity, and purifies NOx, HC, and CO. The GPF 42 is a porous ceramic structure in which the front and rear ends of adjacent cells are alternately sealed. Exhaust gas flows into cells with open upstream ends of the GPF 42 and passes through the porous walls between adjacent cells, capturing PM (particulate matter) in the exhaust gas.

[0020] The ECU (Electronic Control Unit) 100 is an electronic control unit that performs control processing related to the engine 10. The ECU 100 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 100 executes various control processing related to the engine 10 by running programs installed in the memory on the CPU. Various sensors are connected to the ECU 100, which will be described in detail later. The ECU 100 is an example of an engine control device, and functionally implements a lubrication completion determination unit, a lubrication maintenance determination unit, and an execution unit, which will be described in detail later.

[0021] An ignition switch 31, an oil temperature sensor 32, an air flow meter 33, and a crank angle sensor 34 are connected to the ECU 100, and output signals from these various sensors are input to the ECU 100. The ignition switch 31 detects the on / off state of the ignition. The oil temperature sensor 32 detects the temperature of the lubricating oil that lubricates the engine 10. The air flow meter 33 detects the amount of intake air. The crank angle sensor 34 detects the rotation angle of the crankshaft 15.

[0022] The ECU 100 calculates the engine speed based on the detection value of the crank angle sensor 34, and calculates the engine load based on the engine speed and the intake air amount. The ECU 100 calculates the target engine speed and target load based on the accelerator opening, and controls the fuel injection amount, intake air amount, ignition timing, port injection rate, and in-cylinder injection rate so that the engine speed and load become the target engine speed and target load, respectively.

[0023] 2 is an explanatory diagram of the lubricating oil distribution path. Lubricating oil stored in the oil pan 11c is sucked from the oil pan 11c through the oil strainer 50 by the suction force of the oil pump 52. The sucked lubricating oil passes through the oil filter 56, then passes through the main gallery 11d formed in the engine 10, and flows through the cylinder head 11a and cylinder block 11b. A portion of the engine oil that flows through the cylinder block 11b is supplied to the oil jet 26. The lubricating oil is then collected again in the oil pan 11c.

[0024] The oil pump 52 is a known variable displacement type that can change the amount of oil discharged. The oil pump 52 and the main gallery 11d are connected by an oil passage 60. An oil passage 61 branches off from the oil passage 60 between the oil filter 56 and the main gallery 11d. The oil passage 61 is connected to an oil inlet of an oil control valve (hereinafter referred to as OCV) 54, which is a linear solenoid valve. The oil outlet of the OCV 54 is connected to the oil pump 52 via an oil passage 62. The OCV 54 opens and closes under the control of the ECU 100. The opening and closing of the OCV 54 changes the flow rate of lubricating oil introduced into the pressure chamber of the oil pump 52, thereby changing the oil pressure in the pressure chamber. This changes the capacity of the oil pump 52, and changes the amount of lubricating oil discharged. As a result, the pressure in the lubricating oil distribution path (hereinafter referred to as oil pressure) is adjusted.

[0025] [Piston warm-up control] Next, the piston warm-up control executed by the ECU 100 will be described. Fig. 3 is a flowchart showing an example of the piston warm-up control executed by the ECU 100. This flowchart is repeatedly executed while the ignition is on. The ECU 100 determines whether or not there is a request to start the engine 10 (step S1). If the answer is No in step S1, this control ends.

[0026] If the answer to step S1 is Yes, the ECU 100 determines whether engine lubrication was completed during the previous operation of the engine 10 (step S2). Specifically, if the cumulative intake air amount during the previous operation of the engine 10 is equal to or greater than the first threshold, it is determined that lubrication has been completed. This is because the larger the cumulative intake air amount during the previous operation, the higher the cumulative rotation speed of the engine 10, which in turn increases the cumulative discharge amount of the oil pump 52 linked to the rotation of the engine 10. Therefore, the first threshold is set to a lower limit value at which it is determined that lubrication of the engine 10 has been completed by lubricating oil having been distributed to each sliding part of the engine 10. The first threshold is set in advance based on experimental results and simulation results. Note that while the engine 10 is operating, the ECU 100 constantly calculates the cumulative intake air amount, which is the cumulative value of the amount of air taken into the engine 10, based on the detection value of the air flow meter 33. Step S2 is an example of processing executed by the lubrication completion determination unit.

[0027] If the answer is Yes in step S2, the ECU 100 determines whether the lubrication of the engine 10 is maintained (step S3). Specifically, if the stop time of the engine 10 from when the engine 10 is stopped until a start request is made is less than the second threshold, it is determined that the lubrication of the engine 10 is maintained. This is because the shorter the stop time of the engine 10, the more sufficiently the oil film is maintained on each sliding part of the engine 10. Therefore, the second threshold is set to a maximum value at which it can be considered that a sufficient oil film remains on each sliding part of the engine 10 and that the lubrication is maintained when the lubricated engine 10 is stopped. The second threshold is set in advance based on experimental results and simulation results. The ECU 100 calculates the stop time of the engine 10 using a soak timer. Step S3 is an example of processing executed by the lubrication maintenance determination unit.

[0028] If the answer is No in step S2 or S3, the ECU 100 starts the engine 10 without executing the injection suppression process described below (step S4). When the engine 10 starts, the oil pump 52 is driven, and lubricating oil is circulated through the engine 10 and injected from the oil jet 26 toward the piston 13.

[0029] If the answers in steps S2 and S3 are Yes, while starting the engine 10 (step S5), the oil pressure is controlled to be lower than the valve opening pressure of the on-off valve of the oil jet 26 so as to suppress the injection of lubricating oil from the oil jet 26 (step S6). Specifically, the ECU 100 controls the OCV 54 to control the capacity of the oil pump 52, thereby lowering the oil pressure below that in the case of No in step S2. As a result, the injection of lubricating oil from the oil jet 26 toward the piston 13 is suppressed, but the oil pump 52 is driven so that the lubricating oil circulates through the engine 10.

[0030] 4 is a graph showing the temperature change of the piston 13 with and without injection of lubricating oil from the oil jet 26. When injection from the oil jet 26 is present from the start of the engine 10, the temperature of the piston 13 rises gradually. In contrast, when injection from the oil jet 26 is not present, the temperature of the piston 13 rises significantly from the start of the engine 10, and remains higher than when injection from the oil jet 26 is present. In this way, by suppressing injection of lubricating oil from the oil jet 26, it is possible to promote warming up of the piston 13.

[0031] As described above, if lubrication has been completed during the previous operation of the engine 10 and lubrication is maintained when a request to start the engine 10 is made, the engine 10 is started and lubricating oil is circulated in the engine 10 while suppressing injection of lubricating oil from the oil jet 26. This ensures lubrication of the engine 10 while promoting warm-up of the piston 13.

[0032] FIG. 5 is a timing chart showing an example of piston warm-up control. This diagram shows the transitions of the cumulative intake air volume, soak timer, and oil pressure. When the engine 10 starts, the oil pressure is controlled to a high pressure to promote lubrication of the engine 10, and the cumulative intake air volume increases (time t1). The oil pressure is then returned to normal control (time t2), and the cumulative intake air volume becomes equal to or greater than the first threshold (time t3). Note that under normal control, the oil pressure continues to inject lubricating oil from the oil jet 26.

[0033] When engine 10 is stopped, the oil pressure is controlled to zero, the value of the cumulative intake air volume is stored as history in non-volatile memory, the cumulative intake air volume is reset to its initial value, and the soak timer starts counting the time engine 10 is stopped (time t4). If engine 10 is started while the soak timer is below the second threshold, the soak timer is reset to its initial value. Furthermore, because the cumulative intake air volume during the previous operation of engine 10 read from memory is equal to or greater than the first threshold, the oil pressure is controlled to a level that allows lubricating oil to circulate through engine 10 but inhibits injection of lubricating oil from oil jet 26 (time t5). Note that when engine 10 is subsequently started, calculation of the cumulative intake air volume is similarly started, and when engine 10 is stopped, the soak timer similarly starts counting the time engine 10 is stopped.

[0034] In the above embodiment, the first threshold value is shown as a fixed value, but is not limited to this and may be a variable value that varies depending on the temperature of the lubricating oil. FIG. 6 is an example of a map that defines the first threshold value. As shown in FIG. 6, the higher the temperature of the lubricating oil, the lower the first threshold value. This is because the higher the temperature of the lubricating oil, the lower the viscosity of the lubricating oil, and the shorter the time required to lubricate the engine 10 while it is running.

[0035] In the above embodiment, the cumulative rotation speed, which is the cumulative value of the rotation speed of the engine 10 while it is running, may be used instead of the cumulative intake air amount. This is because the operation of the oil pump 52 is linked to the rotation of the engine 10, and the higher the cumulative rotation speed of the engine 10, the greater the cumulative discharge amount of lubricating oil from the oil pump 52. This makes it possible to accurately determine whether lubrication of the engine 10 has been completed.

[0036] In the above embodiment, the ECU 100 that controls the engine 10 mounted on a vehicle has been described as an example of an engine control device, but the present invention is not limited to this. For example, the contents of the above embodiment can also be applied to engine control devices mounted on motorcycles, etc., and engine control devices mounted on things other than vehicles, such as ships and construction machinery. Furthermore, the vehicle on which such an ECU is mounted may be an engine vehicle equipped with only an engine as a power source for running, or may be a hybrid vehicle equipped with an engine and a motor as power sources for running.

[0037] 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 as defined in the claims. [Explanation of symbols]

[0038] 10 Engine 13 Piston 26 Oil Jet 52 Oil pump 100 ECU (engine control device, lubrication completion determination unit, lubrication maintenance determination unit, execution unit)

Claims

[Claim 1] A control device for an engine in which lubricating oil circulates through an engine that is equipped with an oil jet that injects lubricating oil toward a piston while the engine is running, a lubrication completion determination unit that determines whether lubrication of the engine has been completed during the previous operation of the engine before a start request for the engine is received; a lubrication maintenance determination unit that determines whether lubrication of the engine is maintained when the start request is received; an execution unit that, when a positive determination is made by the lubrication completion determination unit and the lubrication maintenance determination unit, starts the engine and circulates lubricating oil through the engine while executing an injection suppression process that suppresses injection of lubricating oil from the oil jet, the lubrication completion determination unit determines that lubrication of the engine has been completed when an integrated intake air amount, which is an integrated value of an intake air amount of the engine during the previous operation of the engine before the start request is received, is equal to or greater than a first threshold value; the lubrication maintenance determination unit determines that lubrication of the engine is maintained when a stop time of the engine from when the engine is stopped until the start request is made is less than a second threshold value; the lubrication completion determination unit changes the first threshold value to a smaller value as the temperature of the lubricating oil increases, the injection suppression process is a process of reducing the pressure of the lubricating oil when a positive determination is made by the lubrication completion determination unit and the lubrication maintenance determination unit, compared to when a negative determination is made by at least one of the lubrication completion determination unit and the lubrication maintenance determination unit; The oil jet is provided with an on-off valve that opens and closes according to the pressure of the lubricating oil, The injection suppression process is a process of controlling the pressure of the lubricating oil to be lower than the valve opening pressure of the on-off valve of the oil jet so as to suppress the injection of the lubricating oil from the oil jet, the execution unit executes the injection suppression process immediately after the engine starts when the lubrication completion determination unit and the lubrication maintenance determination unit make affirmative determinations, An engine control device, wherein if a negative judgment is made by at least one of the lubrication completion judgment unit and the lubrication maintenance judgment unit, the injection suppression process is not executed, and the lubricating oil pressure is controlled to high pressure, and then normal control is performed in which the lubricating oil pressure is controlled at a pressure lower than the high pressure control, and the lubricating oil pressure in the normal control is a pressure at which the injection of lubricating oil from the oil jet continues.

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