JP7631851B2 - Internal combustion engine inspection equipment - Google Patents

Description

The present invention relates to an internal combustion engine inspection method and an internal combustion engine inspection device.

When inspecting internal combustion engines, if the engine is combusted for inspection, equipment for handling the 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 of combusting internal combustion engines for 100% inspection in mass production is enormous.

In response to this, Patent Document 1 discloses a method for inspecting an engine (internal combustion engine) in which the engine (internal combustion engine) is motored and vibrations are measured without burning the engine.

Patent No. 4073899

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

The present invention has been made in consideration of the above problems, and aims to provide an internal combustion engine inspection method and an internal combustion engine inspection device that are low-cost and fully guarantee the function and performance of the internal combustion engine.

According to one aspect of the present invention, there is provided an inspection device for an internal combustion engine for inspecting whether the internal combustion engine is normal . 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 a piston and a crankshaft, and a compression ratio control mechanism for changing the compression ratio by regulating the attitude of the link mechanism. The inspection device includes a pressurizing mechanism for pressurizing gas to be introduced into the internal combustion engine to a pressure at which the cylinder pressure in the combustion stroke of the internal combustion engine can be reproduced by motoring , and introducing the pressurized gas into the intake passage, and a vibration sensor for detecting vibration of the crank mechanism. The intake passage and the exhaust passage are connected via a surge tank so that the gas discharged into the exhaust passage is returned to the intake passage. The surge tank includes a constant pressure valve 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 is a predetermined pressure. The inspection device determines whether the compression ratio control mechanism is normal based on the output of the vibration sensor.

According to the present invention, gas pressurized to a pressure that can reproduce the 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 an internal combustion engine inspection method that is low cost and fully guarantees the function and performance of the internal combustion engine.

FIG. 1 is a schematic diagram of an internal combustion engine inspection device according to an embodiment of the present invention. 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. 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. FIG. 4 is a flowchart illustrating a method for inspecting an internal combustion engine according to an embodiment of the present invention.

The following describes an embodiment of the present invention with reference to the drawings.

Figure 1 is a schematic diagram of an internal combustion engine inspection device 100 according to an embodiment of the present invention.

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 composed of 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, and a controller 7. In addition, 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 can also be applied to multi-cylinder internal combustion engines.

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 the return passage 4 of the inspection device 100.

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

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 arranged on the inclined surface on the intake side and an exhaust valve 121 arranged on the inclined surface on the exhaust side. An ignition plug 17 is arranged 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.

The variable compression ratio mechanism (VCR) 15 is a mechanism that utilizes a multi-link piston-crank mechanism that has been made public by the applicant. The variable compression ratio mechanism 15 includes a link mechanism 15A consisting of multiple 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 the crank pin 151A of the crankshaft 151 and is connected to the piston 14 via the upper link 152. The lower link 153 is also 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.

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

The cylinder 13 of the internal combustion engine 1 is provided with an internal cylinder pressure sensor (not shown) that detects the internal cylinder pressure. Information on the internal cylinder pressure detected by the internal cylinder pressure sensor is transmitted to the controller 7.

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 via a return passage 4. That is, the intake passage 11 and the exhaust passage 12 are configured so that gas exhausted to the exhaust passage 12 returns to the intake passage 11 via the return passage 4.

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 the controller 7.

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 air supplied from the compressor 2 to the intake passage 11 via the return passage 4 falls below a certain pressure. This maintains the pressure of the air in the intake passage 11 at a predetermined pressure.

The return 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 return passage 4.

In addition, a surge tank 5 is provided in the return passage 4 to suppress air pulsation caused by pressure differences.

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

The vibration sensor (condition detection sensor) 6 is installed on the side 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 described below, when inspecting the internal combustion engine 1, when motoring begins, the vibration sensor 6 detects vibrations caused by the stroke operation of the internal combustion engine 1. The vibration information detected by the vibration sensor 6 is sent to the controller 7.

The controller 7 is composed of a computer equipped with a central processing unit (CPU), read only memory (ROM), random access memory (RAM) and an input/output interface (I/O interface), and performs integrated control of the internal combustion engine inspection device 100. The controller 7 can 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.

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 the vibration of the internal combustion engine 1 during the stroke operation is detected by the vibration sensor 6. Then, based on the detected vibration information, it is determined whether the operating state of the variable compression ratio mechanism 15 is normal or not.

By the way, 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 close to the design upper limit. In particular, when the combustion chamber pressure of a variable compression ratio mechanism (VCR) is close to the design upper limit, the compression ratio control mechanism such as the control link is easily loaded, so it is preferable to carry out meticulous design and quality control to prevent seizure and the like, and to carry out an inspection just in case. In this case, it is desirable 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 the stroke operation to inspect the internal combustion engine, separate equipment for handling the fuel, air conditioning, and exhaust treatment equipment are required. In addition, it takes time to connect the internal combustion engine to these facilities. For this reason, when carrying out the combustion stroke and carrying out a full inspection of the internal combustion engine in mass production, the cost becomes enormous. On the other hand, when the internal combustion engine is inspected by motoring the internal combustion engine, even if the air in the combustion chamber is adiabatically compressed to increase the pressure in the combustion chamber, it is not possible to reproduce the high pressure as high as that during combustion.

In this embodiment, the outside air is pressurized to a pressure that can reproduce the in-cylinder pressure during 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, air pressurized to a pressure that can reproduce the in-cylinder pressure during the combustion stroke of the internal combustion engine 1 is drawn into the combustion chamber 16, so that 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.

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 this embodiment (this embodiment). In FIG. 2, t ₁ to t ₂ are the intake stroke, t ₂ to t ₃ are the compression stroke, t ₃ to t ₄ are the expansion stroke, and t ₄ to t ₅ are the exhaust stroke. Also, t ₁ is the timing of the top dead center in the intake stroke, t ₂ is the timing of the bottom dead center in the intake stroke (compression stroke), t ₃ is the timing of the top dead center in the compression stroke (expansion stroke), and t ₄ 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 timing t ₃ of the top dead center of the compression stroke to the timing t ₄ of the bottom dead center is referred to as the expansion stroke.

As shown in Fig. 2, in normal combustion, the intake valve 111 opens at _t1 , and as the piston 14 descends, air at atmospheric pressure Pa is drawn into the combustion chamber 16. Therefore, the cylinder pressure also becomes atmospheric pressure Pa. On the other hand, in this embodiment, air pressurized by the compressor 2 is drawn in, so the cylinder pressure becomes _P1 , which is higher than atmospheric pressure Pa. Here, _P1 is a pressure at which the cylinder pressure becomes equal to the maximum cylinder pressure _Pmax in normal combustion at timing _t3 of the top dead center in the compression stroke (expansion stroke) described later. 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 .

At the timing of bottom dead _center , the intake valve 111 is closed, and during the compression stroke, the air in the combustion chamber 16 is compressed with the rise of the piston 14, and the cylinder pressure gradually rises. In normal combustion, fuel is injected during the compression stroke, and combustion begins by spark ignition at t ₂ '. As a result, the cylinder pressure rises suddenly and reaches a maximum value P _max at t ₃ '. On the other hand, in this embodiment in which air compressed by the compressor 2 is sucked in, since the cylinder pressure at t ₂ at the start of the compression stroke is pressure P ₁ greater than atmospheric pressure Pa, the cylinder pressure reaches a pressure equivalent to the maximum value P _max in normal combustion at t ₃ at the timing of top dead center. In contrast, when air at atmospheric pressure Pa is introduced into the internal combustion engine 1 and motored, since the cylinder pressure at t ₂ at the start of the compression stroke is atmospheric pressure Pa, the cylinder pressure at the timing t ₃ of the top dead center in the compression stroke only rises to P _2, which is smaller than P _max . In normal combustion, the in-cylinder pressure reaches the maximum value _Pmax at _t3 ', which is slightly later than the timing _t3 of top dead center. In this embodiment, however, the in-cylinder pressure reaches the maximum value _Pmax at the timing _t3 of top dead center.

During the expansion stroke from _t3 to _t4 , the cylinder pressure gradually decreases as the air in the combustion chamber 16 expands with the downward movement of the piston 14. As described above, in normal combustion, the cylinder pressure reaches its maximum value _Pmax at _t3 ', which is slightly later than _t3 , so the cylinder pressure decreases from t3 _' to _t4 .

At the timing _t4 of the bottom dead center, the cylinder pressure becomes _P3 in both normal combustion and this embodiment. Here, the 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 smaller value than the pressure _P1 at the time of air intake into the combustion chamber 16 in this embodiment.

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 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 atmospheric pressure Pa. In addition, 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.

In this manner, in this embodiment, air compressed by the compressor 2 is drawn into the combustion chamber 16, so that an in-cylinder pressure equivalent to the maximum value P _max of the in-cylinder pressure during normal combustion can be reproduced.

Fig. 3 is a timing chart showing the relationship between the cycle and the in-cylinder pressure of the internal combustion engine 1 in the internal combustion engine inspection method according to the embodiment of the present invention. Fig. 3 shows the in-cylinder pressure in the n-1th cycle and the nth cycle of the internal combustion engine 1. In Fig. 3, _t1 to _t2 , _t2 to _t3 , _t2 to _t3 , and _t3 to _t4 respectively represent the intake stroke ( _t1 to _t2 ), compression stroke ( _t2 to _t3 ), expansion stroke ( _t3 to _t4 ), and exhaust stroke ( _t4 to _t5 ) of the n-1th cycle. Also, _t5 - _t6 , _t6 - _t7 , _t7 - _t8 , and _t8 - _t9 are the intake stroke ( _t5 - _t6 ), compression stroke ( _t6 - _t7 ), expansion stroke ( _t7 - _t8 ), and exhaust stroke ( _t8 - _t9 ) of the nth cycle, respectively. Also, _t1 , _t3 , _t5 , _t7 , and _t9 are the timings of top dead center, and _t2 , _t4 , _t6 , and _t8 are the timings of bottom dead center.

The intake stroke (t ₁ to t ₂ ), compression stroke (t ₂ to t ₃ ), and expansion stroke (t ₃ to t ₄ ) of the (n−1)th cycle are the same as those in FIG. 2, and therefore description thereof will be omitted.

As described above, during the expansion stroke from t ₃ to t ₄ , gas leaks (blow-by) from the gap between the piston 14 and the cylinder wall (piston-bore), so the in-cylinder pressure drops to P _{3 ,} which is lower than P ₁ .

When the exhaust valve 121 opens at _t4 , the gas (air) in the combustion chamber 16 is exhausted to the exhaust passage 12 during the exhaust stroke from _t4 to _t5 . 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, the in-cylinder pressure does not drop to atmospheric pressure Pa during the exhaust stroke, and the in-cylinder pressure _P3 at the start of the exhaust stroke is maintained.

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.

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. In other words, 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. The predetermined pressure here is a pressure that can reproduce the in-cylinder pressure during combustion in the internal combustion engine 1.

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 P ₁ that reaches a pressure equivalent to the combustion pressure of the internal combustion engine 1 at the timing t ₇ 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 the gas leak (blow-by) is compensated for. Therefore, the in-cylinder pressure during the intake stroke (t ₁ to t ₂ ) of the n-1th cycle becomes equal to the in-cylinder pressure during the intake stroke (t ₅ to t ₆ ) of the n-th cycle.

In addition, since the exhaust pressure during 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 of the intake passage 11 caused by air being drawn into the combustion chamber 16 during the intake stroke. If this pulsation is not absorbed, a case may occur in which the in-cylinder pressure during the intake stroke does not reach the expected pressure P ₁ 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 within the passage is absorbed by the surge tank 5. In addition, when the internal combustion engine 1 has multiple cylinders, the pulsation between the cylinders is also eliminated by the surge tank 5. Therefore, the reduction in pressure during the intake stroke is suppressed.

As described above, the in-cylinder pressure during the intake stroke ( _t5 to _t6 ) of the nth cycle is _P1 , which is equal to the in-cylinder pressure during the intake stroke ( _t1 to _t2 ) of the (n-1)th cycle. Therefore, when the piston 14 rises during the compression stroke ( _t6 to _t7 ) of the nth cycle, the in-cylinder pressure reaches a pressure equal to the maximum in-cylinder pressure _Pmax during combustion in the internal combustion engine 1 at the timing _t7 of the top dead center. In other words, the combustion pressure of the internal combustion engine 1 is reproduced at the timing _t7 of the top dead center.

As in the (n-1)th cycle, in the nth cycle, during the expansion stroke ( _t7 to _t8 ), the in-cylinder pressure drops from _P1 to _P3 , which is a drop by the amount of gas leakage (blow-by). 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).

In this way, the internal combustion engine 1 reproduces the combustion pressure in each cycle during motoring. 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.

Figure 4 is a flowchart explaining a method for inspecting an 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 other problems, is inspected.

As shown in FIG. 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 judgment step (S103) for judging 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 judgment step (S103) are all executed by the controller 7 simultaneously and continuously for a predetermined time.

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 the gas in the passages (intake passage 11, exhaust passage 12, 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.

Step S101 is an introduction step in which outside air is introduced 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. In addition, 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 the 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.

Step S102 is a motoring step for motoring the internal combustion engine 1. In the motoring step (S102), the controller 7 drives a motoring motor external to 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 becomes equal to the maximum in-cylinder pressure P _max during combustion in the internal combustion engine 1. That is, the in-cylinder pressure during combustion is reproduced.

In addition, at the timing of bottom dead center in the expansion stroke of motoring, the pressure inside the cylinder is lower than during the intake stroke by the amount of gas leakage (blow-by). During the exhaust stroke of motoring, the air inside 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.

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 loss caused by gas leakage (blow-by).

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 the vibration information of the main body of the internal combustion engine 1 detected by the vibration sensor 6 during motoring. The correlation between the vibration of the main 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, etc. Therefore, from the vibration information of the main 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 has actually occurred 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).

In the judgment step (S103), if 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, the controller 7 judges that an abnormality has occurred. If an abnormality has been determined, the controller 7 notifies an operator, etc., of the abnormality via a monitor, etc.

On the other hand, if the internal combustion engine 1 is predicted to be normal, the controller 7 continues to execute the introduction process (S101), the motoring process (S102), and the determination process (S103).

The controller 7 continues the processing in the introduction step (S101), motoring step (S102), and judgment 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 judged to be abnormal in the judgment step (S103). Note that the predetermined time here is a time sufficient for an abnormality or a sign of an abnormality to appear if the inspection target (compression ratio control mechanism 15B) is not normal, and can be set in advance by experiment, etc.

The above-described embodiment of the internal combustion engine 1 inspection method and internal combustion engine inspection device 100 can provide the following effects.

According to the method for inspecting an internal combustion engine 1, air (gas) pressurized by a compressor (pressurizing mechanism) 2 to a pressure capable of reproducing the in-cylinder pressure during 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 air (gas) pressurized to a pressure capable of reproducing the in-cylinder pressure during 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. In other words, it is possible to provide a method for inspecting an internal combustion engine 1 at low cost and with sufficient assurance of the function and performance of the internal combustion engine 1.

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

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 during 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.

The inspection method for the internal combustion engine 1 determines whether the compression ratio control mechanism 15B is normal or not. In this way, the compression ratio control mechanism 15B, which is particularly susceptible to seizure and other problems, is inspected, so the function and performance of the internal combustion engine 1 can be fully guaranteed through the inspection.

According to the inspection method for the internal combustion engine 1, the vibration sensor 6 detects the vibration of the main body of the internal combustion engine 1 during motoring, and the detected information is used to determine whether the compression ratio control mechanism 15B is normal or not. In this way, the internal combustion engine 1 can be inspected at low cost because it is possible to determine whether the compression ratio control mechanism 15B is normal or not by detecting the vibration during motoring without performing combustion in the internal combustion engine 1.

The internal combustion engine inspection device 100 is equipped with a compressor (pressurizing mechanism) 2 that pressurizes the air (gas) introduced into the internal combustion engine 1 to a pressure that allows the cylinder pressure during 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 during the compression stroke by motoring the internal combustion engine 1 and drawing the pressurized air (gas) into the combustion chamber 16. In other words, 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 sufficient assurance of the function and performance of the internal combustion engine 1.

According to the internal combustion engine inspection device 100, the intake passage 11 and 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 can be reproduced by motoring in the second and subsequent cycles of the internal combustion engine 1 to be equivalent to the cylinder pressure during the combustion stroke of the internal combustion engine 1. In other words, the power consumption for pressurization can be suppressed, and the internal combustion engine 1 can be inspected at a lower cost.

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. 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.

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 pulsations caused by the pressure difference between the exhaust passage 12 and the intake passage 11 and pulsations between the cylinders, and suppresses the drop in pressure during the intake stroke. Therefore, by motoring, it is possible to reproduce the same in-cylinder pressure as during the combustion stroke of the internal combustion engine 1, and it is possible to inspect the internal combustion engine 1 at low cost while fully guaranteeing the function and performance of the internal combustion engine 1.

The internal combustion engine inspection device 100 inspects the compression ratio control mechanism 15B of the variable compression ratio mechanism 15. In this way, the compression ratio control mechanism 15B, which is particularly susceptible to seizure and other problems, is inspected, so the function and performance of the internal combustion engine 1 can be fully guaranteed through the inspection.

The internal combustion engine inspection device 100 is equipped with a vibration sensor 6 that detects vibrations of the main body of the internal combustion engine 1. This makes it possible to detect vibrations of the main 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.

In this embodiment, the compressor 2 is used as a pressurizing mechanism for pressurizing the air introduced into the intake passage 11, but the pressurizing mechanism is not necessarily limited to this as long as it is possible to pressurize the gas introduced into the intake passage 11. Furthermore, the gas 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.

In addition, in this embodiment, the internal combustion engine 1 uses a 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 type of crank mechanism. In this case, the crank mechanism can be the subject 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.

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 determine whether there is an abnormality in the piston slap sound of the piston 14, or to determine whether there is an abnormality in the hammering sound caused by vibration of the main body of the internal combustion engine 1.

In addition, in this embodiment, the compression ratio control mechanism 15B is judged to be normal or not during motoring, but the judgment of whether the compression ratio control mechanism 15B is normal or not may be performed after motoring is performed. In other words, the controller 7 may perform motoring for a predetermined time, and then judge whether the compression ratio control mechanism 15B is normal or not after motoring ends based on the vibration data detected during motoring.

In addition, in this embodiment, the vibration sensor 6 detects the vibration of the main 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.

In addition, in order to suppress the drop 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 an inspection method for the internal combustion engine 1 that is low cost and fully guarantees the function and performance of the internal combustion engine 1.

Although the embodiments of the present invention have been described above, the above embodiments merely show some of the application examples of the present invention, and are not intended to limit the technical scope of the present invention to the specific configurations of the above embodiments.

Reference Signs List 1 Internal combustion engine 2 Compressor 3 Constant pressure valve 4 Return 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 (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 in the surge tank for adjusting an 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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