Internal combustion engine inspection equipment

Abstract

To provide an internal combustion engine inspection method and an internal combustion engine inspection apparatus, at low costs and with sufficiently secured function and performance of the internal combustion engine.SOLUTION: An internal combustion engine inspection method inspects whether an internal combustion engine 1 is normal by using an internal combustion engine inspection apparatus 100. The inspection method includes: an introduction step of introducing, into an intake channel 11 of the internal combustion engine 1, air compressed by a pressurizing mechanism 2 of the inspection apparatus 100 to pressure with which in-cylinder pressure of the internal combustion engine 1 in a combustion stroke can be reproduced; and a motoring step of motoring the internal combustion engine 1. The inspection method further included a determination step of detecting, during or after the motoring, a value of a parameter enabling determination as to whether the engine 1 is normal, and determining whether the internal combustion engine 1 is normal on the basis of the detected value of the parameter.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method and an apparatus for inspecting an internal combustion engine. [Background technology]

[0002] When inspecting an internal combustion engine by burning the engine, equipment for handling fuel, air conditioning, exhaust treatment, etc. are required. In addition, it takes time to connect the internal combustion engine to these facilities. For this reason, there is a problem that the cost is extremely high when burning the internal combustion engine and inspecting all the engines in mass production.

[0003] In response to this, Patent Document 1 discloses a method for inspecting an engine (internal combustion engine) in which vibrations are measured by motoring the engine (internal combustion engine) without burning the engine. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 4073899 Summary of the Invention [Problem to be solved by the invention]

[0005] In order to fully guarantee the function and performance of the internal combustion engine, it is preferable to inspect the internal combustion engine with the combustion chamber pressure of the internal combustion engine near the design upper limit value, that is, by reproducing the combustion pressure of the internal combustion engine. In the inspection method of the internal combustion engine described in Patent Document 1, air at atmospheric pressure is introduced into the combustion chamber and the internal combustion engine is inspected by motoring. Therefore, although the pressure in the combustion chamber rises during the compression stroke, it is not possible to reproduce a high pressure as high as that during combustion. In other words, the inspection method of the above document cannot reproduce the combustion pressure when the internal combustion engine is operating under a real environment. Therefore, there is a risk that the inspection method of the internal combustion engine described in Patent Document 1 will not be able to fully guarantee the function and performance of the internal combustion engine.

[0006] The present invention has been made in consideration of the above problems, and has an object to provide an internal combustion engine inspection method and apparatus which are low-cost and can fully guarantee the function and performance of the internal combustion engine. [Means for solving the problem]

[0007] According to one aspect of the present invention, an internal combustion engine Check whether is normal or not Internal Combustion Engine Inspection Device is provided. The internal combustion engine includes a cylinder, an intake passage and an exhaust passage connected to the cylinder, a link mechanism consisting of a plurality of links provided between the piston and the crankshaft, and a compression ratio control mechanism that changes the compression ratio by regulating the position of the link mechanism. This test The device is configured to supply gas to the internal combustion engine. In the combustion process of Cylinder Cylinder pressure By motoring Pressurize to a reproducible pressure And the intake passage Introduce to The compression ratio control mechanism includes a pressurizing mechanism and a vibration sensor that detects vibration of the crank mechanism. The intake passage and the exhaust passage are connected via a surge tank so that gas discharged to the exhaust passage is returned to the intake passage. The surge tank includes a constant pressure valve that adjusts the amount of gas introduced from the pressurizing mechanism so that the pressure of the gas introduced from the pressurizing mechanism to the intake passage becomes a predetermined pressure. The inspection device determines whether the compression ratio control mechanism is normal or not based on the output of the vibration sensor. Effect of the Invention

[0008] According to the present invention, gas pressurized to a pressure capable of reproducing the in-cylinder pressure during the combustion stroke of an internal combustion engine is drawn into the combustion chamber, so that the combustion pressure of an internal combustion engine can be reproduced and the internal combustion engine can be inspected without performing combustion in the internal combustion engine. In other words, it is possible to provide a method for inspecting an internal combustion engine at low cost and with sufficient assurance of the function and performance of the internal combustion engine. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic configuration diagram of an internal combustion engine inspection device according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a timing chart showing the relationship between the cycle and the in-cylinder pressure of the internal combustion engine in normal combustion, the present embodiment, and a comparative example. [Diagram 3] FIG. 3 is a timing chart showing the relationship between the cycle of the internal combustion engine and the in-cylinder pressure in the internal combustion engine inspection method according to the embodiment of the present invention. [Figure 4] FIG. 4 is a flowchart illustrating a method for inspecting an internal combustion engine according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0011] FIG. 1 is a schematic configuration diagram of an internal combustion engine inspection device 100 according to an embodiment of the present invention.

[0012] The internal combustion engine inspection device 100 is configured by installing the internal combustion engine 1 to be inspected in the inspection device main body. The inspection device main body is configured with a compressor (pressurizing mechanism) 2, a constant pressure valve 3, a return passage 4, a surge tank 5, a vibration sensor (condition detection sensor) 6, a controller 7, etc. Also, a motor for motoring (not shown) is connected to the internal combustion engine 1. Note that although only one cylinder is shown in FIG. 1, this embodiment is also applicable to a multi-cylinder internal combustion engine.

[0013] The internal combustion engine 1 is, for example, an internal combustion engine for a vehicle such as an automobile, and has an intake passage 11 and an exhaust passage 12. The intake passage 11 and the exhaust passage 12 are connected via a return passage 4 of the inspection device 100.

[0014] The internal combustion engine 1 is, for example, a direct injection type spark ignition internal combustion engine having a cylinder 13, and a piston 14 that reciprocates within the cylinder 13 and a variable compression ratio mechanism (VCR) 15 that drives the piston 14 are provided within a cylinder block 13A.

[0015] The internal combustion engine 1 also has a combustion chamber 16 in the cylinder 13. The combustion chamber 16 is configured as a so-called pent roof type, with an intake valve 111 disposed on an inclined surface on the intake side and an exhaust valve 121 disposed on an inclined surface on the exhaust side. An ignition plug 17 is disposed along the axis of the cylinder 13 at approximately the center of the combustion chamber 16 surrounded by the intake valve 111 and the exhaust valve 121.

[0016] The variable compression ratio mechanism (VCR) 15 is a mechanism that utilizes a multi-link piston-crank mechanism that has been publicly known by the applicant. The variable compression ratio mechanism 15 includes a link mechanism 15A consisting of a plurality of links 152, 153 provided between the piston 14 and the crankshaft 151, and a compression ratio control mechanism 15B that regulates (adjusts) the attitude of the link mechanism 15A to change the compression ratio. The link mechanism 15A includes an upper link 152 and a lower link 153, and the compression ratio control mechanism 15B includes a control link 154 and a control shaft 155. The lower link 153 is rotatably fixed to a crank pin 151A of the crankshaft 151, and is connected to the piston 14 via the upper link 152. The lower link 153 is connected to the control shaft 155 via the control link 154. The control link 154 is connected to a position offset from the rotation axis of the control shaft 155. The control shaft 155 is rotated by an electric motor 156 via, for example, a rack-and-pinion mechanism. The electric motor 156 is configured to be controllable by the controller 7 of the inspection device 100.

[0017] With the above configuration, when control shaft 155 rotates and control link 154 is pulled down, lower link 153 rotates about crank pin 151A as an axis and upper link 152 is pushed up. As a result, the top dead center position of piston 14 rises. Conversely, when control link 154 is pushed up, upper link 152 is pulled down and the top dead center position of piston 14 drops. In this way, variable compression ratio mechanism 15 is able to change the so-called mechanical compression ratio by changing the top dead center position of piston 14.

[0018] An internal cylinder pressure sensor (not shown) for detecting the internal cylinder pressure is provided in the cylinder 13 of the internal combustion engine 1. Information on the internal cylinder pressure detected by the internal cylinder pressure sensor is transmitted to the controller .

[0019] The intake passage 11 is a passage through which gas flows into the combustion chamber 16, and is connected to the combustion chamber 16 via an intake valve 111. The exhaust passage 12 is a passage through which exhaust gas from the combustion chamber 16 flows, and is connected to the combustion chamber 16 via an exhaust valve 121. The intake passage 11 and the exhaust passage 12 are connected to each other via a return passage 4. That is, the intake passage 11 and the exhaust passage 12 are configured such that gas exhausted to the exhaust passage 12 returns to the intake passage 11 via the return passage 4.

[0020] The compressor 2 is a pressurizing mechanism provided outside the internal combustion engine 1, which pressurizes outside air and supplies the pressurized air to the intake passage 11 via the return passage 4. The compressor 2 is controlled by a controller .

[0021] The constant pressure valve 3 is, for example, a relief valve, and is provided in a surge tank 5 between the compressor 2 and the return passage 4. The constant pressure valve 3 opens when the pressure of air supplied from the compressor 2 to the intake passage 11 via the return passage 4 falls below a certain level, thereby maintaining the pressure of the air in the intake passage 11 at a predetermined level.

[0022] The recirculation passage 4 is a passage that connects the intake passage 11 and the exhaust passage 12. The gas exhausted to the exhaust passage 12 is guided to the intake passage 11 by the recirculation passage 4.

[0023] In addition, the return passage 4 is provided with a surge tank 5 for suppressing air pulsation caused by a pressure difference.

[0024] In addition, pressure sensors (not shown) that detect the pressure of gas in the passages (intake passage 11, exhaust passage 12, and return passage 4) are provided in the passages. Pressure information detected by the pressure sensors is transmitted to the controller 7.

[0025] The vibration sensor (condition detection sensor) 6 is installed on the side surface of the outer wall of the cylinder block 13A of the cylinder 13, and detects vibrations of the main body of the internal combustion engine 1. As will be described later, when inspecting the internal combustion engine 1, when motoring starts, the vibration sensor 6 detects vibrations caused by stroke operation of the internal combustion engine 1. The vibration information detected by the vibration sensor 6 is transmitted to the controller 7.

[0026] The controller 7 is composed of a computer equipped with a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM) and an input / output interface (I / O interface), and performs overall control of the internal combustion engine inspection device 100. The controller 7 may also be composed of multiple microcomputers. The controller 7 performs, for example, drive control of the compressor 2, the motoring motor and the electric motor 156, and judges whether the variable compression ratio mechanism 15 is normal or abnormal based on vibration information from the vibration sensor 6. The controller 7 also executes processes for controlling the internal combustion engine inspection device 100 by executing specific programs.

[0027] In the internal combustion engine inspection device 100 configured as described above, the motor for motoring is driven to perform a stroke operation of the variable compression ratio mechanism 15, i.e., motoring is performed, and vibrations of the internal combustion engine 1 during the stroke operation are detected by the vibration sensor 6. Then, based on the detected vibration information, it is determined whether or not the operating state of the variable compression ratio mechanism 15 is normal.

[0028] Incidentally, in order to fully guarantee the function and performance of an internal combustion engine, it is preferable to inspect the internal combustion engine with the combustion chamber pressure near the design upper limit. In particular, when the combustion chamber pressure of a variable compression ratio mechanism (VCR) is near the design upper limit, a load is likely to be placed on the compression ratio control mechanism such as a control link, and it is preferable to carry out a meticulous design and quality control to prevent seizure and the like, as well as to carry out an inspection just in case. In this case, it is preferable to reproduce the combustion pressure of the internal combustion engine and carry out the inspection. However, in order to actually use fuel and carry out a stroke operation to inspect the internal combustion engine, separate equipment for handling the fuel, air conditioning, and equipment for exhaust treatment are required. In addition, it takes time to connect the internal combustion engine to these facilities. For this reason, when carrying out a combustion stroke and carrying out a full inspection of internal combustion engines in mass production, the cost becomes extremely high. On the other hand, when the internal combustion engine is inspected by motoring the internal combustion engine, even if the pressure in the combustion chamber is increased by adiabatically compressing the air in the combustion chamber, it is not possible to reproduce a high pressure as high as that during combustion.

[0029] Therefore, in this embodiment, the outside air is pressurized to a pressure that can reproduce the in-cylinder pressure in the combustion stroke of the internal combustion engine 1 by a compressor (pressurizing mechanism) 2 outside the internal combustion engine 1, and the pressurized air is introduced into the intake passage 11. As a result, when the pressurized air is drawn into the combustion chamber 16 of the internal combustion engine 1 by motoring and compressed by the rise of the piston 14, the pressure in the combustion chamber 16 rises to a pressure equivalent to the combustion pressure of the internal combustion engine 1. In this way, since the air pressurized to a pressure that can reproduce the in-cylinder pressure in the combustion stroke of the internal combustion engine 1 is drawn into the combustion chamber 16, it is possible to reproduce the combustion pressure of the internal combustion engine 1 and inspect the internal combustion engine 1 without performing combustion in the internal combustion engine 1.

[0030] FIG. 2 is a timing chart showing the relationship between the cycle of the internal combustion engine 1 and the cylinder pressure. In FIG. 2, the cylinder pressure when combustion is performed in the internal combustion engine 1 (normal combustion) is compared with the cylinder pressure during motoring in the inspection method of the present embodiment (this embodiment). In FIG. 2, t1 to t2 are the intake stroke, t2 to t3 are the compression stroke, t3 to t4 are the expansion stroke, and t4 to t5 are the exhaust stroke. Also, t1 is the timing of the top dead center in the intake stroke, t2 is the timing of the bottom dead center in the intake stroke (compression stroke), t3 is the timing of the top dead center in the compression stroke (expansion stroke), and t4 is the timing of the bottom dead center in the expansion stroke. Note that, during motoring, gas expansion due to combustion does not occur, but for convenience, the period from the timing t3 of the top dead center of the compression stroke to the timing t4 of the bottom dead center is referred to as the expansion stroke.

[0031] As shown in FIG. 2, in normal combustion, when the intake valve 111 opens at t1 and the piston 14 descends, air at atmospheric pressure Pa is drawn into the combustion chamber 16. Therefore, the in-cylinder pressure also becomes atmospheric pressure Pa. On the other hand, in this embodiment, since air pressurized by the compressor 2 is drawn in, the in-cylinder pressure becomes P1, which is higher than atmospheric pressure Pa. Here, P1 is the maximum in-cylinder pressure P in normal combustion at timing t3 of top dead center in the compression stroke (expansion stroke) described later. max The compressor 2 pressurizes outside air and supplies it to the intake passage 11 so that the pressure of the air drawn into the combustion chamber 16 becomes P1.

[0032] At the bottom dead center timing t2, the intake valve 111 is closed, and during the compression stroke, the air in the combustion chamber 16 is compressed as the piston 14 rises, causing the cylinder pressure to gradually rise. In normal combustion, fuel is injected during the compression stroke, and combustion begins with a spark ignition at t2'. This causes the cylinder pressure to rise suddenly, reaching a maximum value P max On the other hand, in the present embodiment in which air compressed by the compressor 2 is sucked in, the cylinder pressure at time t2 when the compression stroke starts is a pressure P1 that is greater than the atmospheric pressure Pa, so that at time t3, which is the timing of the top dead center, the cylinder pressure reaches the maximum value Pmax In contrast, when air at atmospheric pressure Pa is introduced into the internal combustion engine 1 and motored, the cylinder pressure at time t2 when the compression stroke starts is atmospheric pressure Pa, so the cylinder pressure at time t3 of the top dead center in the compression stroke is P max In normal combustion, the cylinder pressure reaches its maximum value P at t3', which is slightly later than t3, the timing of the top dead center. max In this embodiment, the maximum value P max reaches.

[0033] During the expansion stroke from t3 to t4, as the piston 14 descends and the air in the combustion chamber 16 expands, the cylinder pressure gradually decreases. As described above, in normal combustion, the cylinder pressure reaches a maximum value P max In order to reach this, the in-cylinder pressure decreases from t3' to t4.

[0034] At t4, which is the timing of bottom dead center, the in-cylinder pressure becomes P3 in both normal combustion and this embodiment. Here, the in-cylinder pressure P3 is higher than the atmospheric pressure Pa, but due to gas leakage (blow-by) from the gap between the piston and the cylinder wall (piston-bore), it is a lower value than the pressure P1 at the time of air intake into the combustion chamber 16 in this embodiment.

[0035] When the exhaust valve 121 opens at t4, in normal combustion, the in-cylinder pressure becomes atmospheric pressure Pa. On the other hand, in this embodiment, exhaust gas from the combustion chamber 16, which has a pressure higher than the atmospheric pressure Pa, is recirculated from the exhaust passage 12 to the intake passage 11 via the recirculation passage 4. Therefore, even during the exhaust stroke when the exhaust valve 121 is open, the in-cylinder pressure is maintained at P3, which is higher than the atmospheric pressure Pa. Also, as will be described later, in this embodiment, air pressurized by the compressor 2 is introduced into the intake passage 11 together with the recirculated air (exhaust gas) so that the in-cylinder pressure becomes P1 at the start of the intake stroke of the next cycle.

[0036] In this manner, in this embodiment, the air compressed by the compressor 2 is drawn into the combustion chamber 16, so that the maximum value P max It is possible to reproduce the same in-cylinder pressure as above.

[0037] Fig. 3 is a timing chart showing the relationship between the cycle and the cylinder pressure of the internal combustion engine 1 in the inspection method for an internal combustion engine according to an embodiment of the present invention. Fig. 3 shows the n-1th cycle and the nth cycle of the internal combustion engine 1. In Fig. 3, t1-t2, t2-t3, t2-t3, and t3-t4 respectively represent the intake stroke (t1-t2), compression stroke (t2-t3), expansion stroke (t3-t4), and exhaust stroke (t4-t5) of the n-1th cycle. Also, t5-t6, t6-t7, t7-t8, and t8-t9 respectively represent the intake stroke (t5-t6), compression stroke (t6-t7), expansion stroke (t7-t8), and exhaust stroke (t8-t9) of the nth cycle. In addition, t1, t3, t5, t7, and t9 are the timings of the top dead center, and t2, t4, t6, and t8 are the timings of the bottom dead center.

[0038] The intake stroke (t1 to t2), compression stroke (t2 to t3), and expansion stroke (t3 to t4) of the (n-1)th cycle are the same as those in FIG. 2, and therefore description thereof will be omitted.

[0039] As described above, during the expansion stroke from t3 to t4, gas leaks (blow-by) from the gap between the piston 14 and the cylinder wall (piston-bore), so the in-cylinder pressure drops to P3, which is lower than P1.

[0040] When the exhaust valve 121 opens at t4, in the exhaust stroke from t4 to t5, gas (air) in the combustion chamber 16 is exhausted to the exhaust passage 12. Because the exhaust passage 12 is connected to the intake passage 11, the air exhausted to the exhaust passage 12 is returned to the intake passage 11. For this reason, in this embodiment, in the exhaust stroke, the in-cylinder pressure does not drop to atmospheric pressure Pa, and the in-cylinder pressure P3 at the start of the exhaust stroke is maintained.

[0041] During the exhaust stroke (t4 to t5), outside air pressurized by the compressor 2 is supplied to the intake passage 11 via the constant pressure valve 3. That is, the air pressurized by the compressor 2 is introduced into the intake passage 11 together with the recirculated air (exhaust air) from the exhaust passage 12.

[0042] Here, the constant pressure valve 3 is configured to open when the air sent from the compressor 2 to the intake passage 11 falls below a certain pressure, thereby maintaining the pressure of the gas introduced into the intake passage 11 at a predetermined pressure. That is, the constant pressure valve 3 maintains the pressure of the mixture of the recirculated gas introduced into the intake passage 11 and the gas supplied from the compressor 2 at a predetermined pressure. Note that the predetermined pressure here is a pressure that can reproduce the in-cylinder pressure during combustion in the internal combustion engine 1.

[0043] In this way, during the exhaust stroke, the air pressurized by the compressor 2 is introduced into the intake passage 11 together with the recirculated air. The constant pressure valve 3 adjusts the amount of air introduced from the compressor 2 into the intake passage 11 so that the pressure of the gas introduced into the intake passage 11 is a pressure that can reproduce the in-cylinder pressure during combustion in the internal combustion engine 1. Therefore, the in-cylinder pressure during the intake stroke of the next cycle (n-th cycle) of the internal combustion engine 1 becomes a pressure P1 that reaches a pressure equivalent to the combustion pressure of the internal combustion engine 1 at the timing t7 of the top dead center of the compression stroke (expansion stroke). In other words, during the exhaust stroke, the air pressurized by the compressor 2 is introduced into the intake passage 11, and the pressure reduced by gas leakage (blow-by) is compensated for. Therefore, the in-cylinder pressure during the intake stroke (t1 to t2) of the n-1th cycle becomes equal to the in-cylinder pressure during the intake stroke (t5 to t6) of the n-th cycle.

[0044] In addition, since the exhaust pressure in the exhaust stroke is reduced due to gas leakage (blow-by), when pressurized air is introduced into the intake passage 11, a pressure difference occurs in the passages (intake passage 11, exhaust passage 12, and return passage 4), and there is a risk of pulsation occurring. In addition, there is a risk of pulsation occurring due to a reduction in the pressure in the intake passage 11 caused by air being drawn into the combustion chamber 16 in the intake stroke. If this pulsation is not absorbed, a case may occur in which the in-cylinder pressure in the intake stroke does not reach the expected pressure P1 due to resonance or the like. In contrast, in this embodiment, the exhaust passage 12 and the intake passage 11 are connected via the surge tank 5 provided in the return passage 4, and the pulsation in the passage is absorbed by the surge tank 5. In addition, when the internal combustion engine 1 has a plurality of cylinders, the pulsation between the cylinders is also eliminated by the surge tank 5. Therefore, the reduction in pressure in the intake stroke is suppressed.

[0045] As described above, the cylinder pressure during the intake stroke (t5 to t6) of the nth cycle is P1, which is equal to the cylinder pressure during the intake stroke (t1 to t2) of the n-1th cycle. Therefore, when the piston 14 rises during the compression stroke (t6 to t7) of the nth cycle, the cylinder pressure at the timing t7 of the top dead center becomes the maximum cylinder pressure P max That is, at the timing t7 of the top dead center, the combustion pressure of the internal combustion engine 1 is reproduced.

[0046] As in the n-1th cycle, in the nth cycle, the cylinder pressure drops from P1 to P3, which is a pressure drop due to gas leakage (blow-by), during the expansion stroke (t7 to t8). During the exhaust stroke (t8 to t9), pressurized air is introduced from the compressor 2 into the intake passage 11, compensating for the pressure drop due to gas leakage (blow-by).

[0047] In this way, the combustion pressure is reproduced in each cycle during motoring in the internal combustion engine 1. The vibration sensor 6, which detects the vibration of the main body of the internal combustion engine 1, detects the vibration caused by the stroke operation of the internal combustion engine 1 during motoring, and the detected vibration data can be used to predict abnormalities such as seizure in the variable compression ratio mechanism 15.

[0048] 4 is a flowchart illustrating a method for inspecting the internal combustion engine 1 according to this embodiment. In this embodiment, the compression ratio control mechanism 15B of the variable compression ratio mechanism 15 in the internal combustion engine 1, which is particularly susceptible to seizure and the like, is inspected.

[0049] 4, the method for inspecting the internal combustion engine 1 according to this embodiment includes an introduction step (S101) for introducing outside air, a motoring step (S102), and a determination step (S103) for determining whether the compression ratio control mechanism 15B to be inspected is normal or not. Note that the following processes in the introduction step (S101), motoring step (S102), and determination step (S103) are all executed by the controller 7 simultaneously and continuously for a predetermined time.

[0050] When the internal combustion engine 1 is installed in the inspection device main body and the inspection device 100 for the internal combustion engine 1 is started, the controller 7 starts the inspection process for the internal combustion engine 1. During the inspection period, the controller 7 constantly receives information on the pressure of gas in the passages (the intake passage 11, the exhaust passage 12, and the return passage 4), the in-cylinder pressure of the internal combustion engine 1, and the vibration of the main body of the internal combustion engine 1.

[0051] Step S101 is an introduction step of introducing outside air into the internal combustion engine 1 to be inspected. In the introduction step (S101), the controller 7 pressurizes the outside air (air) to a predetermined pressure by the compressor 2, and introduces the pressurized air into the intake passage 11 via the return passage 4. The air in the intake passage 11 is maintained at a predetermined pressure by the action of the constant pressure valve 3 between the compressor 2 and the intake passage 11. Note that the predetermined pressure here is a pressure at which the cylinder pressure of the internal combustion engine 1 becomes equal to the cylinder pressure during combustion of the internal combustion engine 1 under an actual environment in the motoring step (S102). As described above, the introduction step (S101) is performed continuously for a predetermined time, and pressurized air is constantly sent from the compressor 2 to the intake passage 11 during the inspection period.

[0052] Step S102 is a motoring step for motoring the internal combustion engine 1. In the motoring step (S102), the controller 7 drives a motor for motoring outside the internal combustion engine 1 to motor the internal combustion engine 1. As described above, in the intake stroke of motoring, air pressurized by the compressor 2 is sucked in, and at the timing of the top dead center in the compression stroke, the in-cylinder pressure is the maximum in-cylinder pressure P during combustion in the internal combustion engine 1. max That is, the cylinder pressure during combustion is reproduced.

[0053] At the bottom dead center of the expansion stroke during motoring, the cylinder pressure is lower than that during the intake stroke by the amount of gas leakage (blow-by). During the exhaust stroke during motoring, the air in the cylinder is exhausted to the exhaust passage 12, and the exhausted air is returned from the exhaust passage 12 to the intake passage 11 via the surge tank 5.

[0054] When exhaust gas is being recirculated, in the introduction step (S101), air pressurized by the compressor 2 is introduced into the intake passage 11 together with the recirculated exhaust gas (air), compensating for the pressure drop caused by gas leakage (blow-by).

[0055] Step S103 is a judgment step for judging whether the compression ratio control mechanism 15B to be inspected is normal or not. In the judgment step (S103), the controller 7 judges whether the compression ratio control mechanism 15B is normal or not from vibration information of the body of the internal combustion engine 1 detected by the vibration sensor 6 during motoring. The correlation between the vibration of the body of the internal combustion engine 1 and whether the compression ratio control mechanism 15B is normal or abnormal can be obtained in advance by experiments or the like. Therefore, from the vibration information of the body of the internal combustion engine 1, it is possible to predict an abnormality such as seizure in the control link 154 of the compression ratio control mechanism 15B. Note that the abnormality here includes not only a case where an abnormality such as seizure actually occurs in the compression ratio control mechanism 15B, but also a case where an abnormality such as seizure is predicted to occur if motoring is continued (when there is a sign of an abnormality).

[0056] In the determination step (S103), the controller 7 determines that an abnormality has occurred when an abnormality such as seizure of the compression ratio control mechanism 15B is predicted from the vibration information of the main body of the internal combustion engine 1. When an abnormality has been determined, the controller 7 notifies an operator or the like of the abnormality through a monitor or the like.

[0057] On the other hand, when it is predicted that the internal combustion engine 1 is normal, the controller 7 continues to execute the introduction step (S101), the motoring step (S102), and the determination step (S103).

[0058] The controller 7 continues the processes in the introduction step (S101), the motoring step (S102), and the determination step (S103) until a predetermined time has elapsed since the start of the inspection of the internal combustion engine 1, or until the inspection target (compression ratio control mechanism 15B) is determined to be abnormal in the determination step (S103). Note that the predetermined time here is a time that is sufficient for an abnormality or a sign of an abnormality to appear when the inspection target (compression ratio control mechanism 15B) is not normal, and can be set in advance by experiment or the like.

[0059] According to the inspection method for the internal combustion engine 1 and the inspection device 100 for the internal combustion engine of the above-described embodiment, the following effects can be obtained.

[0060] According to the method for inspecting the internal combustion engine 1, air (gas) pressurized by the compressor (pressurizing mechanism) 2 to a pressure capable of reproducing the in-cylinder pressure in the combustion stroke of the internal combustion engine 1 is introduced into the intake passage 11, and the internal combustion engine 1 is motored to draw the pressurized air (gas) into the combustion chamber 16 of the internal combustion engine 1. In this way, since the air (gas) pressurized to a pressure capable of reproducing the in-cylinder pressure in the combustion stroke of the internal combustion engine 1 is drawn into the combustion chamber 16, the combustion pressure of the internal combustion engine 1 can be reproduced and the internal combustion engine 1 can be inspected without performing combustion in the internal combustion engine 1. That is, it is possible to provide a method for inspecting the internal combustion engine 1 at low cost and with sufficient assurance of the function and performance of the internal combustion engine 1.

[0061] According to the method for inspecting the internal combustion engine 1, during the exhaust stroke of motoring, the air (gas) exhausted to the exhaust passage 12 of the internal combustion engine 1 is returned to the intake passage 11. This makes it possible to prevent the in-cylinder pressure of the internal combustion engine 1 during the exhaust stroke from dropping to atmospheric pressure Pa. Therefore, by increasing the pressure by the amount of pressure drop due to air (gas) leakage (blow-by), it is possible to reproduce an in-cylinder pressure equivalent to the in-cylinder pressure during the combustion stroke of the internal combustion engine 1 by motoring even in the second and subsequent cycles of the internal combustion engine 1. In other words, it is possible to reduce power consumption for pressurization, and to provide a method for inspecting the internal combustion engine 1 at lower cost.

[0062] According to the inspection method for the internal combustion engine 1, the constant pressure valve 3 between the compressor 2 and the intake passage 11 adjusts the amount of air (gas) introduced from the compressor (pressurizing mechanism) 2 so that the pressure of the air (gas) introduced into the intake passage 11 is maintained at a pressure (predetermined pressure) that can reproduce the in-cylinder pressure in the combustion stroke of the internal combustion engine 1. In this way, the amount of air (gas) introduced from the compressor (pressurizing mechanism) 2 is adjusted so that the pressure of the air in the intake passage 11 is always at a predetermined pressure, so that the in-cylinder pressure equivalent to the in-cylinder pressure during combustion of the internal combustion engine 1 can be reproduced by motoring no matter how many cycles of the internal combustion engine 1 are performed. In addition, in the second and subsequent cycles of the internal combustion engine 1, the pressure is increased by the amount of pressure reduction due to air (gas) leakage (blow-by), so that the power consumption for pressurization can be suppressed, and a lower-cost inspection method for the internal combustion engine 1 can be provided.

[0063] According to the inspection method for the internal combustion engine 1, it is determined whether or not the compression ratio control mechanism 15B is normal. In this manner, since the compression ratio control mechanism 15B, which is particularly susceptible to seizure and the like, is the subject of inspection, the function and performance of the internal combustion engine 1 can be sufficiently guaranteed by the inspection.

[0064] According to the inspection method for the internal combustion engine 1, the vibration sensor 6 detects vibrations of the main body of the internal combustion engine 1 during motoring, and it is determined whether the compression ratio control mechanism 15B is normal or not from the detection information. In this way, since it is determined whether the compression ratio control mechanism 15B is normal or not by detecting vibrations during motoring without performing combustion in the internal combustion engine 1, it is possible to inspect the internal combustion engine 1 at low cost.

[0065] The internal combustion engine inspection device 100 includes a compressor (pressurizing mechanism) 2 that pressurizes the air (gas) to be introduced into the internal combustion engine 1 to a pressure that allows the cylinder pressure in the combustion stroke of the internal combustion engine 1 to be reproduced by motoring, and supplies the compressed air (gas) to the intake passage 11. As a result, even if combustion is not performed in the internal combustion engine 1, the combustion pressure of the internal combustion engine 1 can be reproduced in the compression stroke by motoring the internal combustion engine 1 and drawing the pressurized air (gas) into the combustion chamber 16. That is, the internal combustion engine 1 can be inspected by reproducing the combustion pressure of the internal combustion engine 1 by motoring. Therefore, the internal combustion engine 1 can be inspected at low cost with the function and performance of the internal combustion engine 1 fully guaranteed.

[0066] According to the internal combustion engine inspection device 100, the intake passage 11 and the exhaust passage 12 of the internal combustion engine 1 are connected. As a result, during the exhaust stroke of motoring, the air (gas) exhausted to the exhaust passage 12 of the internal combustion engine 1 is returned to the intake passage 11, so that the cylinder pressure of the internal combustion engine 1 during the exhaust stroke can be prevented from dropping to atmospheric pressure Pa. Therefore, if the pressure is increased by the amount of pressure drop due to air (gas) leakage (blow-by), the cylinder pressure equivalent to the cylinder pressure during the combustion stroke of the internal combustion engine 1 can be reproduced by motoring even in the second and subsequent cycles of the internal combustion engine 1. That is, the power consumption for pressurization can be suppressed, and the internal combustion engine 1 can be inspected at a lower cost.

[0067] According to the internal combustion engine inspection device 100, a constant pressure valve 3 is provided between the compressor (pressurizing mechanism) 2 and the intake passage 11. The constant pressure valve 3 adjusts the amount of air (gas) introduced from the compressor (pressurizing mechanism) 2 so that the pressure of the air (gas) introduced from the compressor (pressurizing mechanism) 2 to the intake passage 11 is maintained at a predetermined pressure. As a result, the pressure of the air (gas) in the intake passage 11 is always at a predetermined pressure, so that the cylinder pressure equivalent to the cylinder pressure in the combustion process of the internal combustion engine 1 can be reproduced by motoring no matter how many cycles of the internal combustion engine 1 are performed. In addition, in the second and subsequent cycles of the internal combustion engine 1, the pressure is increased by the amount of pressure reduction due to air (gas) leakage (blow-by), so that the power consumption for pressurization can be suppressed and the internal combustion engine 1 can be inspected at a lower cost.

[0068] According to the internal combustion engine inspection device 100, the exhaust passage 12 and the intake passage 11 are connected via a surge tank 5. This absorbs pulsation caused by the pressure difference between the exhaust passage 12 and the intake passage 11 and pulsation between the cylinders, and suppresses a drop in pressure during the intake stroke. Therefore, it is possible to reproduce an internal cylinder pressure equivalent to the internal cylinder pressure during the combustion stroke of the internal combustion engine 1 by motoring, and it is possible to inspect the internal combustion engine 1 at low cost while fully ensuring the function and performance of the internal combustion engine 1.

[0069] According to the internal combustion engine inspection device 100, the inspection target is the compression ratio control mechanism 15B of the variable compression ratio mechanism 15. In this way, since the inspection target is the compression ratio control mechanism 15B, which is particularly susceptible to seizure and the like, the function and performance of the internal combustion engine 1 can be sufficiently guaranteed by the inspection.

[0070] The internal combustion engine inspection device 100 includes a vibration sensor 6 that detects vibrations of the body of the internal combustion engine 1. This makes it possible to detect vibrations of the body of the internal combustion engine 1 during motoring and to determine whether the compression ratio control mechanism 15B is normal or not from the detection information. Therefore, even if combustion is not performed in the internal combustion engine 1, it is possible to determine whether the compression ratio control mechanism 15B is normal or not from the vibrations during motoring, and therefore it is possible to inspect the internal combustion engine 1 at low cost.

[0071] In this embodiment, the compressor 2 is used as a pressurizing mechanism for pressurizing the air to be introduced into the intake passage 11, but the pressurizing mechanism is not limited to this as long as it can pressurize the gas to be introduced into the intake passage 11. Also, the gas to be introduced into the intake passage 11 is not limited to air. For example, an inert gas such as nitrogen or argon may be introduced into the intake passage 11 from a pressurizing cylinder.

[0072] In addition, in this embodiment, the internal combustion engine 1 uses the variable compression ratio mechanism 15 that utilizes a multi-link piston crank mechanism, but this is not necessarily limited to this, and the internal combustion engine may use another crank mechanism. In this case, the crank mechanism can be the object of inspection, and it can be determined whether the crank mechanism is normal or not from vibration information of the main body of the internal combustion engine 1.

[0073] Furthermore, the object of inspection is not limited to the crank mechanism, and the inspection items are not limited to the presence or absence of seizure, etc. For example, it may be possible to perform abnormality determination for piston slap sound of the piston 14, or abnormality determination for hitting sound caused by vibration of the main body of the internal combustion engine 1.

[0074] In addition, in this embodiment, whether the compression ratio control mechanism 15B is normal or not is determined during motoring, but whether the compression ratio control mechanism 15B is normal or not may be determined after motoring is performed. That is, the controller 7 may perform motoring for a predetermined time, and then, after motoring ends, determine whether the compression ratio control mechanism 15B is normal or not based on data of vibrations detected during motoring.

[0075] In this embodiment, the vibration sensor 6 detects the vibration of the body of the internal combustion engine 1 as a parameter for determining whether the compression ratio control mechanism 15B, which is the part to be inspected, is normal or not, but the parameter is not limited to this. For example, after motoring for a predetermined time, a contamination detection sensor may detect foreign matter in the oil in the cylinder block, and based on the detection information, it may be determined whether the part to be inspected is normal or not. As long as it is possible to determine whether the part to be inspected is normal or not, the parameter to be detected is not particularly limited.

[0076] In addition, in order to suppress a decrease in the cylinder pressure of the internal combustion engine 1 during the exhaust stroke, it is preferable to connect the intake passage 11 and the exhaust passage 12 and recirculate the exhaust gas as in this embodiment, but this is not necessarily limited to this. Even if the intake passage 11 and the exhaust passage 12 are not connected, the combustion pressure of the internal combustion engine 1 can be reproduced by motoring as long as gas pressurized by the pressurizing mechanism 2 is supplied to the intake passage 11. In other words, it is possible to provide a method for inspecting the internal combustion engine 1 at low cost and with sufficient assurance of the function and performance of the internal combustion engine 1.

[0077] Although the embodiments of the present invention have been described above, the above-mentioned embodiments merely show some of the application examples of the present invention, and it is not intended that the technical scope of the present invention be limited to the specific configurations of the above-mentioned embodiments. [Explanation of symbols]

[0078] 1. Internal combustion engine 2. Compressor 3 Constant Pressure Valve 4 Reflux passage 5. Surge Tank 6 Vibration Sensor 7 Controller 11 Intake passage 12 Exhaust passage 13 Cylinder 14 Piston 15 Variable compression ratio mechanism 16 Combustion chamber 100 Internal combustion engine inspection device

Claims

[Claim 1] An inspection device for an internal combustion engine for inspecting whether an internal combustion engine is normal or not, the internal combustion engine includes a cylinder, an intake passage and an exhaust passage connected to the cylinder, a link mechanism including a plurality of links provided between a piston and a crankshaft, and a compression ratio control mechanism that changes a compression ratio by regulating a position of the link mechanism, The inspection device includes: a pressurizing mechanism that pressurizes gas to be introduced into the internal combustion engine to a pressure that can reproduce the internal pressure of the cylinder during a combustion stroke of the internal combustion engine by motoring, and supplies the gas to the intake passage; a vibration sensor that detects vibration of the crank mechanism, the intake passage and the exhaust passage are connected via a surge tank so that gas discharged to the exhaust passage returns to the intake passage, a constant pressure valve disposed within the surge tank for adjusting the amount of gas introduced from the pressurizing mechanism so that the pressure of the gas introduced from the pressurizing mechanism into the intake passage becomes a predetermined pressure; the inspection device determines whether the compression ratio control mechanism is normal or not based on an output of the vibration sensor. Inspection equipment for internal combustion engines.

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