Internal combustion engine control device

Abstract

To provide an internal combustion engine control device suppressing a determination that a hydraulic sensor is in a fixation abnormality involved in reduction in pressure of an oil supply destination.SOLUTION: An engine control device is provided with: a dry-sump type lubrication system; an oil pump disposed in an oil supply passage where oil flows toward a space housing an oil supply part from an oil tank; and a hydraulic sensor detecting hydraulic pressure in the oil supply passage. The control device includes a controller determining existence of fixation abnormality where a detection value of the hydraulic pressure sensor does not vary. The controller determines that an internal pressure in a space is a predetermined value or less (step S4), does not determine the fixation abnormality when it is determined that the internal pressure of the space is the predetermined value or less (step S2), and determines the fixation abnormality on the basis of the detection value of the hydraulic pressure sensor when the internal pressure in the space is higher than the predetermined value (step S5 or step S8).SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a control device for an internal combustion engine configured to supply oil to sliding parts and heat-generating parts provided in the internal combustion engine. [Background technology]

[0002] Patent Document 1 describes an engine control device that includes an oil pump that draws and discharges oil from an oil pan, a variable valve mechanism that operates using oil supplied from the oil pump, and a hydraulic sensor that detects the hydraulic pressure on the discharge side of the oil pump. This control device is configured to determine a sticking abnormality, in which the hydraulic sensor output remains unchanged, when the fluctuation amplitude of the hydraulic sensor output is small and the hydraulic pressure is equal to or less than a low hydraulic pressure determination value. Even when the fluctuation amplitude of the hydraulic sensor output is small and the hydraulic pressure is higher than the low hydraulic pressure determination value, the control device is configured to determine a sticking abnormality in the hydraulic sensor if the operating speed of the variable valve mechanism is not decreasing. Furthermore, when the fluctuation amplitude of the hydraulic sensor output is small, the hydraulic pressure is higher than the low hydraulic pressure determination value, and the operating speed of the variable valve mechanism is decreasing, the control device is configured to determine a hydraulic pressure drop abnormality, in which the hydraulic pressure has decreased due to some factor.

[0003] Patent Document 2 also describes an engine control device that employs a so-called dry sump lubrication system, which includes a drain passage that communicates with the lower end of the engine block and discharges oil from the lower end of the engine block, a scavenge pump provided in the drain passage, an oil tank that receives oil from the engine block via the drain passage and stores the oil, an oil passage that supplies the oil stored in the oil tank to sliding parts and heat-generating parts within the engine, a feed pump provided in the oil passage, and an oil pressure sensor that is provided in the oil passage on the discharge side of the feed pump and detects the pressure of the oil in the oil passage.The engine described in Patent Document 2 also includes a bypass passage that communicates with the drain passage on one side and the oil passage downstream of the feed pump on the other, and a switch valve that switches whether oil that flows from the engine block to the drain passage flows to the oil tank or the oil passage.

[0004] This control device is configured to determine that the feed pump has failed when it detects that the oil pressure detected by the oil pressure sensor has dropped below a predetermined threshold, and by connecting the discharge passage and the oil passage using a switching valve, pump oil from the engine block using the driving force of the scavenge pump without going through the oil tank, and supply the oil to sliding parts and heat-generating parts. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2023-022642 [Patent Document 2] Japanese Patent Application Laid-Open No. 2004-156451 Summary of the Invention [Problem to be solved by the invention]

[0006] The control device described in Patent Document 1 determines that the output of the hydraulic sensor does not change due to a sticking abnormality when the fluctuation amplitude of the output of the hydraulic sensor is small and the hydraulic pressure is equal to or less than a low hydraulic pressure determination value. Meanwhile, the hydraulic pressure on the discharge side of the oil pump is determined based on the amount of oil discharged from the oil pump and the pressure (internal pressure) at the location where the oil is supplied. In other words, even if the oil pump is operating normally and discharging a sufficient amount of oil, if the pressure at the location where the oil is supplied is low (negative pressure), the oil discharged from the oil pump or feed pump will flow smoothly through the oil passage, causing the pressure in the oil passage to drop.

[0007] In an engine employing a dry sump lubrication system configured as described in Patent Document 2, air may be drawn into the engine block at the same time as oil. Furthermore, a dry sump lubrication system typically includes an air passage that draws outside air into the engine block. Therefore, if the amount of air drawn into the engine block is greater than the amount of air supplied to the engine block through the air passage, the pressure inside the cylinder block may become negative, below atmospheric pressure.

[0008] In such cases, the low pressure at the oil supply point causes the oil discharged from the oil pump to be immediately output into the engine block, resulting in a drop in the oil pressure in the oil passage. That is, even if the oil pump is operating normally and discharging a sufficient amount of oil, the oil pressure in the oil passage may drop below the lower limit detectable by the oil pressure sensor or the lower limit set for control purposes. In such cases, even if the oil pressure in the oil passage fluctuates, the output of the oil pressure sensor will remain constant at the lower limit, and the oil pressure value used for control will remain constant, which may lead to an erroneous determination that the oil pressure sensor is stuck.

[0009] This invention was devised with an eye on the above-mentioned technical problems, and aims to provide a control device for an internal combustion engine that can prevent the oil pressure sensor from being judged to be stuck abnormally as the pressure of the oil supply destination decreases. [Means for solving the problem]

[0010] In order to achieve the above-mentioned object, the present invention provides an engine control device comprising: an oil tank that stores oil pumped up from a space that houses at least one of a sliding part and a heat-generating part; an oil supply passage that flows the oil stored in the oil tank into the space; an oil pump provided in the oil supply passage that pumps up the oil stored in the oil tank and pressurizes it toward the space; and a hydraulic sensor that detects the oil pressure in the oil supply passage downstream of the oil pump, wherein the control device comprises a controller that determines whether or not a sticking abnormality exists in which the detection value of the hydraulic sensor does not fluctuate, and the controller comprises an internal pressure determination unit that determines whether the internal pressure of the space is below a predetermined value, and a sticking determination unit that does not determine whether or not a sticking abnormality exists when the internal pressure determination unit determines that the internal pressure of the space is below the predetermined value, and that determines whether or not a sticking abnormality exists when the internal pressure determination unit determines that the internal pressure of the space is higher than the predetermined value.

[0011] In addition, in this invention, the oil pump may include a mechanical oil pump driven by the power of the engine, and the predetermined value may be set to a lower value as the engine rotation speed increases or the oil temperature decreases.

[0012] In this invention, the sticking determination unit may determine that the sticking abnormality has occurred when the duration during which the change in the detected value of the hydraulic sensor is less than a predetermined change amount is equal to or longer than a predetermined time. [Effects of the Invention]

[0013] The engine of the present invention is configured with a so-called dry sump lubrication system in which oil is pumped from a space accommodating sliding parts and heat-generating parts to an oil tank, and then pressure-fed by an oil pump and supplied from the oil tank to the space via an oil supply passage. When the internal pressure of the space is below a predetermined value, a determination of a sticking abnormality is not made, in which case the detection value of a hydraulic pressure sensor detecting hydraulic pressure downstream of the oil pump does not fluctuate. However, when the internal pressure of the space is higher than the predetermined value, a determination of a sticking abnormality is made. Therefore, when the internal pressure of the space drops to below the lower limit pressure detectable by the hydraulic pressure sensor or below a lower limit pressure set for control, a false determination of a sticking abnormality can be prevented, even though the hydraulic pressure sensor is operating normally. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a cross-sectional view schematically showing an example of an engine according to an embodiment of the present invention. [Figure 2] 3 is a flowchart illustrating an example of control executed by a control device according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0015] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The following embodiments of the present invention will be described with reference to the accompanying drawings. Note that the following embodiments are merely examples of specific embodiments of the present invention and are not intended to limit the scope of the present invention.

[0016] The internal combustion engine in an embodiment of the present invention can be configured as a gasoline engine, a diesel engine, or the like. Fig. 1 shows a schematic diagram of an example of a gasoline engine. The gasoline engine (hereinafter simply referred to as engine) 1 shown in Fig. 1 includes a cylinder block 2, a cylinder head 3 provided at the upper end of the cylinder block 2, and a crankcase 4 connected to the lower end of the cylinder block 2. The cylinder block 2 is formed with a cylinder 2a that penetrates in the vertical direction in the drawing, and a piston 5 is provided inside the cylinder 2a so as to move up and down, and a crankshaft 7 is connected to the piston 5 via a connecting rod 6.

[0017] The cylinder head 3 is configured to close the opening on the upper side of the cylinder 2a, and is provided with an intake port (not shown) that takes in fresh air into the cylinder 2a, an exhaust port (not shown) that discharges exhaust gas generated in the cylinder 2a, and a spark plug (not shown) that ignites the mixture of air and fuel in the cylinder 2a.

[0018] The crankcase 4 is formed with a crank chamber 4a that communicates with an opening below the cylinder 2a. This crank chamber 4a is configured to accommodate the lower end of the connecting rod 6 and the crankshaft 7. The lower end of the crank chamber 4a is configured to function as a space to accommodate sliding parts and heat-generating parts provided in the engine 1, specifically as an oil pan 4b that temporarily stores oil O supplied to the space inside the cylinder head 3, the cylinder 2a, or the crank chamber 4a. Because the internal combustion engine in this embodiment of the present invention is equipped with an oil tank 8, which will be described later, the capacity of this oil pan 4b is configured to be smaller than the capacity that can store the entire amount of oil to be supplied to the sliding parts and heat-generating parts.

[0019] Any one of the cylinder head 3, the cylinder block 2, and the crankcase 4 is provided with an intake passage (not shown) for taking in outside air into the crank chamber 4a.

[0020] 1 is configured to supply oil O to sliding parts and heat-generating parts by a so-called dry sump lubrication system. That is, an oil tank 8 that stores the oil O to be supplied to the sliding parts and heat-generating parts is provided in a position independent of the cylinder block 2, cylinder head 3, and crankcase 4 described above.

[0021] The oil tank 8 is formed of a sealed container, and an oil discharge passage 9 communicating with the oil pan 4b is provided at its upper end. A scavenge pump (S / P) 10 is provided in the oil discharge passage 9 for pumping the oil O temporarily stored in the oil pan 4b up to the oil tank 8, and a strainer 11 is provided at the suction port (opening on the oil pan 4b side) of the oil discharge passage 9 for removing foreign matter contained in the oil O stored in the oil pan 4b. The scavenge pump 10 may be a mechanical pump driven by power from the engine 1, or may be an electric pump.

[0022] The oil tank 8 is also provided with an oil supply passage 12 for causing the oil O stored in the oil tank 8 to flow toward a space that houses sliding parts and heat-generating parts provided in the engine 1. That is, one end of the oil supply passage 12 opens to the lower end of the oil tank 8, and the other end opens to, for example, the cylinder head 3. The oil supply passage 12 is provided with an oil pump (O / P) 13 for pumping up and pressure-feeding the oil O stored in the oil tank 8. The oil pump 13 is configured as a mechanical pump that is driven by the power of the engine 1. Note that, although the oil pump 13 is provided in the crankcase 4 in FIG. 1, the location where the oil pump 13 is disposed is not particularly limited.

[0023] Therefore, oil O pumped up from the oil tank 8 by the oil pump 13 and pumped out is supplied to the cylinder head 3 via the oil supply passage 12, flows through sliding parts and heat-generating parts provided in the cylinder head 3, and then drips into the cylinder 2a. Next, the oil flows through the sliding part between the outer circumferential surface of the piston 5 and the wall surface of the cylinder 2a, and then drips into the oil pan 4b. The oil O stored in the oil pan 4b is then pumped up by the scavenge pump 10 and supplied to the oil tank 8 via the oil discharge passage 9. In other words, the oil O is configured to circulate through the cylinder head 3, the cylinder block 2, the crankcase 4, and the oil tank 8.

[0024] 1, a blow-by gas pipe 14 for discharging blow-by gas from the oil tank 8 is provided so as to open at the upper end of the oil tank 8, and the other end of the blow-by gas pipe 14 is connected between an air cleaner 16 provided in an intake pipe 15 for allowing fresh air to flow toward the cylinder 2a and a throttle valve 17. The blow-by gas pipe 14 is provided with a PCV valve 18 for controlling the flow rate of blow-by gas flowing through the blow-by gas pipe 14.

[0025] 1 further includes an oil pressure sensor 19 that detects the oil pressure on the output side (downstream side) of the oil pump 13 in the oil supply passage 12, an internal pressure sensor 20 that detects the pressure inside the cylinder head 3, the cylinder block 2, and the crankcase 4, and an electronic control device (hereinafter referred to as a controller) 21 that determines whether a sticking abnormality occurs when the detected value of the oil pressure sensor 19 does not fluctuate. In the following explanation, the oil pressure on the output side of the oil pump 13 will be referred to simply as the oil pressure without specifying its location, the inside of the cylinder head 3, the cylinder block 2, and the crankcase 4 will be collectively referred to as the oil supply section, and the pressure in the oil supply section will be referred to as the crankcase internal pressure for convenience.

[0026] The controller 21 may be configured to receive signals from various sensors, such as a crank angle sensor 22 that detects the rotation speed of the crankshaft 7 and an oil temperature sensor 23 that detects the temperature of the oil O stored in the oil tank 8. For convenience, FIG. 1 shows an example in which signals are input to the controller 21 from the crank angle sensor 22 and the oil temperature sensor 23 in addition to the oil pressure sensor 19 and the internal pressure sensor 20.

[0027] This controller 21 is mainly composed of a microcomputer, and is configured to receive signals from the oil pressure sensor 19, internal pressure sensor 20, crank angle sensor 22, and oil temperature sensor 23, and to determine whether or not the oil pressure sensor 19 has become stuck based on these input signals and pre-stored arithmetic equations, etc.

[0028] Fig. 2 shows a flowchart for explaining an example of this control. In the control example shown in Fig. 2, first, it is determined whether or not a condition for determining a drop in oil pressure is met (step S1). This step S1 is a step for determining whether or not oil O is being steadily discharged from the oil pump 13, and therefore, for example, it may be determined whether or not a predetermined time has elapsed since the engine 1 was started.

[0029] If the answer in step S1 is negative because the oil pressure drop judgment condition is not met, the oil pressure in the oil supply passage 12 has not increased and it is not possible to judge whether there is a sticking abnormality, so the counter for judging whether there is a sticking abnormality (sticking abnormality judgment counter) is cleared (step S2) and this routine is temporarily terminated.

[0030] On the other hand, if the hydraulic pressure drop determination condition is met and the result of step S1 is affirmative, it is determined whether the detection permission condition is met (step S3). This step S3 is a step for determining whether the condition for determining a sticking abnormality is met, and therefore, it is determined whether the sensors for determining a sticking abnormality have failed due to factors other than a sticking abnormality, such as whether the communication line connecting the hydraulic sensor 19 and the controller 21 has been disconnected.

[0031] If the detection permission condition is not satisfied and the result of step S3 is negative, it is not possible to determine whether a sticking abnormality has occurred. Therefore, the sticking abnormality determination counter is cleared (step S2), and this routine is temporarily terminated.

[0032] On the other hand, if the detection permission condition is met and the answer in step S3 is affirmative, it is determined whether the detected value (internal pressure) of the internal pressure sensor 20 is equal to or less than a predetermined value (step S4). This step S4 is a step for determining whether the internal pressure of the oil supply unit has excessively decreased, causing the oil pressure in the oil supply passage 12 to fall below the lower limit detectable by the oil pressure sensor 19 or below the lower limit set for control, making it impossible to determine whether a sticking abnormality has occurred.

[0033] Here, the principle behind the decrease in the internal pressure of the oil supply section causing the oil pressure in the oil supply passage 12 to decrease, and the reason why a sticking abnormality cannot be determined, will be explained.

[0034] The oil pressure in the oil supply passage 12 described above is determined based on the amount of oil discharged from the oil pump 13 and the internal pressure of the oil supply section. Since the oil pump 13 is a mechanical oil pump, the amount of oil discharged from the oil pump 13 increases as the rotation speed of the crankshaft 7 (engine rotation speed) increases, and the oil pressure increases. Also, the lower the temperature (oil temperature) of the oil O, the higher the flow resistance of the oil O and the higher the oil pressure.

[0035] On the other hand, because the oil pan 4b has a small capacity as described above, air inside the crank chamber 4a may be sucked in at the same time as the oil O when the oil O is pumped up from the oil pan 4b. Therefore, if the amount of air sucked in from the crank chamber 4a is greater than the amount of air introduced from the intake passages provided in any of the cylinder head 3, the cylinder block 2, and the crankcase 4, the internal pressure of the oil supply section drops. Therefore, even if an appropriate amount of oil O is being discharged from the oil pump 13, the discharged oil O quickly flows into the oil supply section, causing a drop in the hydraulic pressure inside the oil supply passage 12.

[0036] The amount of oil pressure drop increases as the crank pressure decreases. Therefore, a decrease in crank pressure may cause the oil pressure in the oil supply passage 12 to drop below the lower limit pressure detectable by the oil pressure sensor 19, or may even drop below a lower limit pressure set for control. In such a case, the oil pressure signal input to the controller 21 and the oil pressure used by the controller 21 do not fluctuate from the lower limit value, so that a sticking abnormality may be determined even though the oil pump 13 operates normally and discharges an appropriate amount of oil O and the oil pressure sensor 19 is normal.

[0037] Therefore, in step S4, it is determined whether a sticking abnormality can be determined by determining whether the detection value of internal pressure sensor 20 is equal to or less than a predetermined value. As described above, the oil pressure detected by oil pressure sensor 19 is based on the amount of oil discharged from oil pump 13 and the internal pressure of the oil supply section, and the amount of oil discharged from oil pump 13 varies depending on engine speed and oil temperature. In other words, if the engine speed is high or the oil temperature is low, the oil pressure detected by oil pressure sensor 19 will be equal to or greater than the above-mentioned lower limit pressure, even if the crankshaft internal pressure is low. Therefore, the predetermined value in step S4 may be set lower as the engine speed is higher or the oil temperature is lower.

[0038] If the result of step S4 is affirmative because the detected value of the internal pressure sensor 20 is equal to or less than the predetermined value, the decrease in the crankshaft internal pressure causes the oil pressure in the oil supply passage 12 to fall below the lower limit pressure detectable by the oil pressure sensor 19, or to fall below the lower limit pressure set for control. In other words, it is not possible to determine whether or not the oil pressure is fluctuating. Therefore, if the result of step S4 is affirmative, the sticking abnormality determination counter is cleared (step S2), and this routine is temporarily terminated. In other words, the sticking abnormality determination is not performed or the determination of the sticking abnormality is prohibited.

[0039] On the other hand, if the detection value of the internal pressure sensor 20 is higher than the predetermined value and therefore a negative determination is made in step S4, the oil pressure can be detected by the oil pressure sensor 19, or the oil pressure is a pressure that can be used for control, and therefore a determination is made as to whether a sticking abnormality has occurred. Specifically, if a negative determination is made in step S4, it is determined whether or not a sticking abnormality has occurred. Specifically, first, it is determined whether or not the amount of change in the signal input from the oil pressure sensor 19 to the controller 21 (amount of change in oil pressure), i.e., the difference between the oil pressure value detected in the previous routine and the oil pressure value detected in the current routine, is less than a predetermined amount of change (step S5).

[0040] If the amount of change in the signal input from the hydraulic sensor 19 to the controller 21 is equal to or greater than the predetermined amount of change and therefore the determination in step S5 is negative, the sticking abnormality determination counter is cleared (step S2), and this routine is temporarily terminated. Conversely, if the amount of change in the signal input from the hydraulic sensor 19 to the controller 21 is less than the predetermined amount of change and therefore the determination in step S5 is positive, the sticking abnormality determination counter is counted up (step S6), and then it is determined whether the sticking abnormality determination counter is equal to or greater than a predetermined value (step S7). Steps S6 and S7 are steps for preventing a sticking abnormality from being determined when the hydraulic pressure temporarily does not fluctuate even though the hydraulic sensor 19 is operating normally. Therefore, the predetermined value in step S7 can be set to a value obtained by dividing a predetermined time for determining a sticking abnormality by the cycle time of this control cycle.

[0041] If the determination in step S7 is negative because the sticking abnormality determination counter is less than the predetermined value, this routine is immediately terminated. Note that it is sufficient to be able to determine whether or not a sticking abnormality has occurred, and if the determination in step S7 is negative, the routine may return to step S5.

[0042] On the other hand, if the determination in step S7 is affirmative because the sticking abnormality determination counter is equal to or greater than the predetermined value, a sticking abnormality determination is made (step S8), and this routine is temporarily terminated. In this case, it is possible that the oil pump 13 is not discharging an appropriate amount of oil O toward the oil supply unit, which may result in a decrease in the lubrication of the sliding parts of the engine 1 or a decrease in the cooling performance of heat-generating parts. Therefore, as a fail-safe control, for example, the upper limit of the output torque of the engine 1 or the rotation speed of the engine 1 may be set lower than normal. Also, because it is not desirable to continue driving the engine 1 and there is a high possibility that maintenance will be required, a warning may be issued to the driver.

[0043] As described above, by determining whether or not there is a sticking abnormality when the crank pressure is higher than a predetermined value, when the crank pressure drops and the oil pressure in the oil supply passage 12 drops to below the lower limit pressure that can be detected by the oil pressure sensor 19 or below the lower limit pressure set for control, it is possible to prevent an erroneous determination of a sticking abnormality even though the oil pressure sensor 19 can operate normally.

[0044] It should be noted that the above step S4 functions as an "internal pressure determination unit" in the embodiment of the present invention, and steps S5 to S8 function as a "sticking determination unit" in the embodiment of the present invention. [Explanation of symbols]

[0045] 1 engine 2a Cylinder 4a crankcase 4b Oil pan 8 Oil Tank 12 Oil supply passage 13 Oil pump 19 Oil pressure sensor 20 Internal pressure sensor 21 Electronic control device (controller) 23 Oil temperature sensor O Oil

Claims

1. An engine control device comprising: an oil tank that stores oil pumped up from a space that houses at least one of a sliding part and a heat generating part; an oil supply passage that causes the oil stored in the oil tank to flow into the space; an oil pump that is provided in the oil supply passage and pumps up the oil stored in the oil tank and pressure-feeds it toward the space; and an oil pressure sensor that detects oil pressure in the oil supply passage downstream of the oil pump, a controller for determining whether or not there is a sticking abnormality in which the detection value of the hydraulic pressure sensor does not fluctuate; The controller an internal pressure determination unit that determines whether the internal pressure of the space is equal to or less than a predetermined value; a sticking determination unit that does not determine whether a sticking abnormality has occurred when the internal pressure determination unit determines that the internal pressure of the space is equal to or lower than the predetermined value, and that determines whether a sticking abnormality has occurred based on the detection value of the hydraulic sensor when the internal pressure determination unit determines that the internal pressure of the space is higher than the predetermined value. An engine control device characterized by:

2. The engine control device according to claim 1, The oil pump includes a mechanical oil pump driven by power of the engine, The predetermined value is set to a lower value as the engine speed increases or the oil temperature decreases. An engine control device characterized by:

3. The engine control device according to claim 1, The sticking determination unit determines that the sticking abnormality has occurred when the duration during which the change in the detected value of the hydraulic sensor is less than a predetermined change amount is equal to or longer than a predetermined time. An engine control device characterized by:

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