JPH0765559B2 - Abnormality diagnosis device for internal combustion engine - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an abnormality diagnosis device for an internal combustion engine that performs knocking control, and particularly to a device for diagnosing abnormality of engine parts (engine body, injector, etc.) other than a knocking sensor. Regarding

(Prior art) Knocking is mainly caused by compression ignition of unburned gas, and if it occurs violently, energy loss (decrease in output)
It is desirable to avoid this, as it will cause an impact on the engine and various parts of the engine, and will also cause a reduction in fuel consumption. However, the light knocking phenomenon itself does not adversely affect the engine, and even if the ignition timing is advanced to cause knocking, the combustion efficiency of the engine can be increased to improve the fuel efficiency of the vehicle. From the viewpoint of improving the fuel efficiency, allowing appropriate knocking is suitable for obtaining the operating state of the engine at the optimum efficiency. Therefore, in order to improve the operating efficiency of the engine and suppress the noise level of knocking to a predetermined value or less, it is necessary to control the knocking strength by adapting it to various operating conditions.

As a conventional knocking control device for performing such control, there is, for example, a device disclosed in Japanese Patent Publication No. 59-48308. In this device, the ignition timing is set according to the operating state, and the ignition timing is corrected based on the output of the knock sensor. That is, when knocking is occurring, the ignition timing is corrected to the retard side, and when knocking is stopped, the ignition timing is advanced to the advance side, thereby advancing the ignition timing as much as possible while enhancing the drivability of the engine. There is.

(Problems to be Solved by the Invention) By the way, the high frequency components due to such knocking include mechanical vibration of the engine and vibration components due to abnormality of the air-fuel ratio in addition to the normal knock vibration. The conventional knocking control device is configured to detect knocking vibration components of the high frequency components and control the ignition timing to suppress knocking, and to detect abnormalities of the internal combustion engine, especially engine parts other than the knocking sensor (engine main body and engine There is no function for diagnosing abnormalities in injectors, etc.).

(Object of the Invention) Therefore, an object of the present invention is to make it possible to diagnose an abnormality of an engine component (engine body, injector, etc.) other than a knocking sensor.

(Structure of the Invention) As shown in the basic conceptual diagram of FIG. 1, an abnormality diagnosing device for an internal combustion engine according to the present invention detects a knock vibration generated in an engine and a knock detecting means a for detecting an operating state of the engine. And an ignition correction amount for each cylinder that sets the basic ignition timing based on the operating state and corrects the basic ignition timing so that the knock vibration level becomes a predetermined value or less. Ignition timing setting means c for correcting the basic ignition timing according to the correction amount, and ignition means d for igniting the air-fuel mixture based on the output of the ignition timing setting means c.
And a setting means e for setting a limit value (advance limit value) of the ignition correction amount between the cylinders to the advance side and a limit value (delay limit value) of the unbalance to the retard side.
And a comparing means f for comparing the actual ignition correction amount determined by the ignition timing setting means c with the advance limit value and the retard limit value, and when the ignition correction amount is equal to or larger than the advance limit value. On the other hand, if it is judged to be too advanced, on the other hand, if it is less than the retard limit value, it is judged to be too retarded.If it is judged to be too advanced, the air-fuel ratio is controlled in the lean direction to prevent excessive advancement. If the state does not change, the first abnormal pattern is determined, if the state changes, the second abnormal pattern is determined, and if it is determined that the retard angle is too large, the air-fuel ratio is controlled in the rich direction. If the state of retarding too much does not change, the third abnormal pattern is judged, and if the state changes, a judging means g for judging the fourth abnormal pattern, and an alarm when the judging means g judges an abnormality. And an alarm means h for issuing.

(Operation) Since the present invention adopts such a configuration, it is possible to appropriately determine the imbalance between the cylinders of the ignition correction amount when the ignition timing is feedback-controlled so as to keep the knocking level at a predetermined value or less, An alarm can be issued in the case of various abnormalities of engine parts other than the knock detecting means, such as abnormal compression ratio, abnormal air-fuel ratio, or misfire. This is because the cause of the first abnormal pattern is defective (fixed open) or misfire of the injector, the cause of the second abnormal pattern is low compression ratio or overrich, and the cause of the third abnormal pattern is This is because the injector is defective (closed and fixed), the mechanical vibration is increased, etc., and the cause of the fourth abnormal pattern is a high compression ratio, over lean, etc., and at least each cause has peculiarities. Therefore, in the present invention, the abnormality of the engine component can be specified in detail for the four patterns from the first to the fourth.

(Example) Hereinafter, the present invention will be described with reference to the drawings.

2 to 7 are views showing an embodiment of the present invention. First, the configuration will be described.

In FIG. 2, reference numeral 1 is an in-cylinder pressure sensor, and the in-cylinder pressure sensor 1 converts the combustion pressure in the cylinder into an electric charge by a piezoelectric element and outputs an electric charge output S ₁ . As shown in detail in FIGS. 3A and 3B, the in-cylinder pressure sensor 1 is screwed to the cylinder head 2 and is formed as a washer of the ignition plug 3, and the outer recess of the cylinder head 2 is formed. The ignition plug 3 is pressed and fixed to the place by the tightening portion 3a of the spark plug 3.

The sensor output S ₁ is input to the charge amplifier 4, and the charge amplifier 4 constitutes a so-called charge-voltage conversion amplifier including an operational amplifier OP, resistors R ₁ and R ₂ and a capacitor C, and the sensor output S ₁ is converted into a voltage signal S. _It is converted to ₂ and output to the bandpass filter 5. Band-pass filter 5 is a frequency band corresponding to knocking vibration of the signal S ₂ (e.g. 6KHz~
Only the signal of 17 KHz) is passed and output to the signal processing circuit 6 as the signal S ₃ .

The signal from the crank angle sensor 7 is input to the signal processing circuit 6, and the crank angle sensor 7 detects the crank angle of the engine. For example, in the case of a 6-cylinder engine, the reference signal Ci is output every 120 ° of the crank angle. The position signal C ₁ is output every 1 ° of the crank angle.

The signal processing circuit 6 is a circuit that detects vibration energy at the time of knocking, and integrates the absolute value of the output signal S ₃ of the bandpass filter 5 and holds and resets the integrated value by the reference signal C ₁ A value corresponding to a predetermined crank angle is preset, and the count of the position signal C ₁ is preset according to the reference signal C ₁ according to the presettable counters 9 and 10 and the outputs of the presettable counters 9 and 10. It is composed of a flip-flop 11 which controls the operation of the absolute value integrator 8.

In this embodiment, the present invention is applied to a 6-cylinder engine, and the compression top dead center is set after the crank angle reference signal Ci is generated.
When the vibration energy at knock is detected at 70 degrees and between 10 degrees and 45 degrees after the compression top dead center, the presettable counters 9 and 10 have crank angles of 80 degrees and 115 degrees, respectively. Make sure that the value corresponding to is preset.

The in-cylinder pressure sensor 1, charge amplifier 4, band pass filter 5, signal processing circuit 6 and crank angle sensor 7 constitute knock detection means 12.

Output S ₄ of absolute value integrator 8 and presettable counter
The output S ₅ of 10 is input to the control unit 13, and the control unit 13 is further input with the signal S ₆ from the operating state detecting means 14. The operating state detecting means 14 detects a parameter indicating the operating state of the engine (for example, intake pipe pressure, engine speed, throttle valve opening, starter motor operation, etc.) and outputs a signal S ₆ . The control unit 13 performs ignition timing control and arithmetic processing for abnormality diagnosis based on each input signal, outputs an ignition signal Sp corresponding to the optimum ignition timing to the ignition means 15, and displays an alarm signal Sa abnormally during abnormality diagnosis. Output to lamp 16. Ignition means 15
Generates a high voltage at this optimum ignition timing to ignite the air-fuel mixture, and the abnormality display lamp 16 is composed of, for example, a light emitting diode and lights up when an abnormality signal Sa is input to display an abnormality of the engine.

The control unit 13 has functions as an ignition timing setting means, a setting means, a comparing means, and a judging means, and the MPU2
1, ROM22, RAM23 and I / O interface 24. The MPU21 fetches the external data required from the I / O interface 24 according to the program written in the ROM22, and also, while exchanging data with the RAM23, calculates the processing value required for knocking control, I / O interface 2 for data processed as required
Output to 4. The I / O interface 24 receives the absolute value integrator 8, the signal from the operating state detecting means 14 and the interrupt signal S ₅ , and the I / O interface 24 outputs the ignition signal Sp and the alarm signal Sa. It The ROM 22 stores a calculation program or the like in the MPU 21, and the RAM 23 is composed of, for example, a non-volatile memory (NVM) and stores data used for calculation in the form of a map and holds the stored content even after the engine is stopped.

FIG. 4 shows an example of the signal waveform of each part at a crank angle of 0 to 120 degrees.

That is, FIG. 4 (A) is a reference signal Ci (120 ° signal in the case of a 6-cylinder engine) generated from the crank angle sensor 7, and FIG. 4 (B) is a position signal C ₁ similarly generated for each crank angle 1 °. (C) is the output signal S ₂ of the charge amplifier 4,
(D) is the output signal S ₃ of the bandpass filter 5, (E) is the output signal S ₇ of the flip-flop 11, and (F) is the absolute value integrator (hereinafter simply referred to as “integrator”) 8 of the signal processing circuit 8 The output signals S ₄ of are shown respectively.

Next, the operation of the signal processing circuit 6 in FIG. 2 will be described.

The integrator 8 is reset by the reference signal Ci at 70 degrees before the compression top dead center, and the preset values (80 °, 115 °) are preset in the presettaple counters (hereinafter simply referred to as “counters”) 9 and 10. It Then, each of these counters starts counting the crank angle position signal C ₁ and the output of the counter 9 is inverted at a crank angle of 80 °, and accordingly the output signal S ₇ of the flip-flop 11 is changed as shown in FIG. ), The reset state of the integrator 8 is released, and the integrator 8 outputs the output signal S _{3 of the} bandpass filter 5.
Start the integration of. Further, since the output of the counter 10 is inverted at the crank angle of 115 °, the output signal S ₇ of the flip-flop 11 becomes high level [H], and the integrator 8 holds the integrated value at that time. Therefore, the integrator 8
The output signal S _{4 of} is changed as shown in FIG.

In this way, the signal processing circuit 6 in FIG. 2 can obtain an integrated value from 10 ° after top dead center to 45 ° after top dead center, that is, a signal value corresponding to a physical quantity related to vibration energy at knocking. it can.

The output S ₅ of the counter 10 at a crank angle of 115 degrees is used as an interrupt signal for the control unit 13,
In response to this, the control unit 13 schedules A / D conversion start described later.

Next, the contents of the program executed by the control unit 13 will be described. FIG. 5 is a flow chart showing a program written in the ROM 22, and P _{1 to} P _{34 in the} figure show respective steps of the flow. In addition,
In FIG. 5, the abnormality determination of the knocking sensor and the abnormality determination of the engine parts other than the knocking sensor are shown together, but the point of the present invention is the portion for performing the abnormality determination of the engine parts other than the knocking sensor, That is, the knocking abnormality display step (P ₉ , P ₁₂ ) in FIG.
This is the part included below.

FIG. 5 is a flow chart of a program for diagnosing an abnormality. When an interrupt request for the signal S ₅ is issued, the control unit 13 starts executing this program.

First, as shown in FIG. 6, the lower limit value Smin of the physical quantity S related to the combustion vibration energy at knocking at P ₁ is Smin = f (N)
Look up from the table map that has the functional relationship. Note that S is A / D converted from the output signal S ₄ of the integrator 8 as shown in step P ₆ described later. Similarly, P ₂
Then, the upper limit value Smax {Smax = f (N)} of S is looked up. The value of Smax may be fixed to a value near the maximum value (usually 5V) that can be A / D converted (for example, 4.9V), but the upper limit value that can be taken by normal S for each rotation speed is checked beforehand. It is preferable to give it as a function of N because an abnormality such as noise can be easily detected.

Then, the slice level SL {SL = f (N)} of the knock level parameter when performing feedback control to the target knock level (trace knock) at P ₃ is looked up,
The base ignition timing B represented by the following functional form is looked up at P ₄ .

B = f (Q, N) However, Q: intake air amount or fuel injection amount Next, at P ₅ , cylinder determination is performed based on the reference signal Ci. That is, it is determined whether or not it is the first cylinder, and if it is the first cylinder, the program proceeds to P ₆ to continue this program, and if it is not the first cylinder, the processing corresponding to each cylinder is performed in another program. . In this case, the contents of the program are the same.

At P ₆ , the physical quantity S related to the combustion vibration energy at knocking
As a result, the output signal S ₄ of the integrator 8 is A / D converted and stored in the memory, and the physical quantity S is compared with the lower limit value Smin and the upper limit value Smax at P ₇ and P ₈ , respectively. When S <Smin, it is determined that the value of S is abnormally small and the sensor signal system is abnormal. The cause may be an open state or a short state of the sensor signal system. In this case, since the charge does not remain in the charge amplifier 4, the signal S ₂ is zero, but the output of the bandpass filter 5
Since a small amount of noise is present on S ₃ , the noise component is integrated by the integrator 8 and a non-zero value is output as the signal S ₄ . It should be noted that Smin corresponds to the value of S in no-load operation, which is a small mechanical vibration detected by the in-cylinder pressure sensor 1 of the plug washer type, and is smaller than the integrated value of noise except for extremely low rotation. Has a large value. Therefore, S
The state of <Smin means that the value of S is abnormally small.

On the other hand, when S> Smax, it is determined that the value of S is abnormally large and the sensor signal system is abnormal. Possible causes are a very large noise on the sensor signal system, a high voltage (several V) in the control unit 13 contacting the line of the signal S ₄ , or an offset of the zero point of the integrator 8. To be

Since the case of the sensor signal system such as described above abnormality it is expected that an error is generated in the knocking determination based on the value of S, P ₉
Displays an abnormality of the sensor signal system in, the process proceeds to P ₁₀ and stored in non-volatile memory (NVM). The abnormal display is not limited to the simple lighting display, and the content may be displayed by the number of times of blinking or the like. That is, two abnormalities of S <Smin and S> Smax are collectively displayed as 1 as an abnormality of the sensor signal system, but the abnormality is not necessarily limited to this, and for example, S <Smin
When it is, the abnormality indicating that the sensor signal is not input (short or open state) is displayed, and when S> Smax, the abnormality indicating that the noise is large or the control unit 13 is abnormal is displayed individually. You may By doing so, maintainability is further improved.
The abnormality display is displayed for each cylinder and is used as a self-diagnosis process.

In P ₁₀ , the cylinder with the abnormal sensor signal system (here, the first
Cylinder) ignition timing correction amount (hereinafter referred to as ignition correction amount) D _1
Is made equal to the ignition correction amount D _r of the most retarded cylinder among other normal cylinders, and the routine proceeds to P ₁₁ . As a result, it is possible to avoid excessive retardation processing of the ignition timing based on the erroneous determination of knocking caused by the abnormality of the sensor signal system.

On the other hand, when S ≧ Smin and S ≦ Smax in P _{7 to} P ₈ , respectively, it is judged that the sensor signal system is normal, and in P ₁₂ , the abnormal display of the sensor signal system is stopped and the data is stored in the nonvolatile memory. To cancel. Next, at P ₁₃ , a knock parameter KN indicating the knock level is calculated according to the following equation.

KN = S- ▲ ▼ However, ▲ ▼: The average value of S at the previous non-knock period P ₁₄ compares the knock parameter KN with the slice level SL, and when KN> SL, it is determined that knock occurs and P _{At 15} , the knock correction amount D ₁ of the first cylinder is increased to the retard side for knock control. In this retard processing, for example, the ignition correction amount D ₁ is calculated according to the following equation.

D ₁ = D ₁ old−α …… However, in the formula of α: retardation correction amount, α is set to α = 1.0 to 2.0 ° CA. D ₁
Is a signed value and can be negative.

On the other hand, when KN ≦ SL in P ₁₄ , it is determined that there is no knock, and in P ₁₆ , the current value is updated according to the following equation.

= K ₁ × ▲ ▼ + k ₂ × S ...... In the formula, k ₁ and k ₂ are constants, but if the operating conditions are almost steady, k ₁ = 15/16, k ₂ = 1/16 is appropriate. Is. Under transient operating conditions, (i) when S> ▲ ▼, k ₁ = 31/32, k ₂ = 1/32 (ii) when S ≦ ▲ ▼, k ₁ = 3/4, k ₂ = 1/4 The degree is reasonable.

Then, on P ₁₇ , replace this time with ▲ ▼, and change to P ₁₈
Then, hold the ignition correction amount D ₁ or make an advance angle correction, and proceed to P ₁₁ . Hold means to hold the ignition correction amount D ₁ at the present value. The reason why such a hold or advance angle correction is performed is that it is desirable to advance the ignition timing as close as possible to near the MBT when there is no knock. Since the resolution of the crank angle sensor 7 is 1 ° CA, the advance angle correction of 1 ° or less is meaningless and is the same as the hold. But,
When retarding, for example, α = 1 ° / 1 knock, but when advancing, if the advance correction amount β is β = 0.1 ° / ignition, the ignition correction amount D ₁ (D ₁ = previous D _The ignition timing will be held until the change of ₁ + β) becomes 1 degree. The number of holds in this case is determined by the ratio of α / β.

Next, at P ₁₁ , the final ignition timing C is calculated according to the following equation, and the ignition signal is output at the timing corresponding to this final ignition timing.
Output Sp to ignite the mixture.

C = B + D _{1 In} this way, when there is no abnormality in the sensor signal system, feedback control of the ignition timing is executed so that knocking is suppressed. Such ignition timing control is executed similarly for the cylinders other than the first cylinder, the ignition correction amount D ₁ to D ₆ of each cylinder is determined.

Next, in P ₁₉ , the average value AVE of the remaining four values except the maximum value and the minimum value among D _{1 to} D ₆ is obtained. At P ₂₀ , the deviation ΔD ₁ of the ignition correction amount D ₁ of the first cylinder from the average value AVE is calculated according to the following equation.

ΔD ₁ = D ₁ −AVE ... Then, in P ₂₁ , the deviation ΔD ₁ is compared with a predetermined value a. “A” corresponds to a limit value of unbalance between the ignition correction amount D ₁ and another cylinder, that is, a limit value of excessive advance (hereinafter referred to as advance limit value). When ΔD ₁ <a, the deviation ΔD ₁ is similarly compared with the retard limit value r at P ₂₂ .

The discrimination results in each step of P ₂₁ and P ₂₂ are as follows.
It can be divided into two modes, which will be described sequentially below.

(I) When ΔD ₁ ≧ a (When the lead angle is too advanced) The cause of the excessive lead angle is considered to be a low compression ratio, an excessive air-fuel ratio, and a small S value due to misfire. Therefore, even if the air-fuel ratio is once diluted, if the determination result that the advance angle is still too advanced appears, it is considered that the cause is as described above.

Therefore, first, to determine the lean flag FL with P _23. The lean flag FL indicates whether or not the air-fuel ratio has been diluted, and indicates that the air-fuel ratio has been diluted when FL = 1 and that it has not been diluted when FL = 0. When FL = 0, after setting the lean flag FL at P ₂₄ , the air-fuel ratio of the first cylinder is diluted at P ₂₅ , and this routine is ended. Then, since the determination result of [Delta] D ₁ ≧ a when the FL = 1 without generating knocking despite the lean of at P ₂₃ has appeared in the next routine, the first cylinder in the P ₂₆ misfire Or the malfunction of the injector (for example, fuel injection of a quantity larger than the required value is being performed) is abnormal (hereinafter,
Error 1) is displayed and stored in the memory.

(II) When ΔD ₁ ≦ r (when retarded too much) First, the rich flag FR is determined in P ₂₇ . Rich flag F
R indicates whether or not the air-fuel ratio is over-enriched, and FR =
When it is 1, it indicates that it is over-enriched, and when FR = 0, it is not over-enriched. FR = 0 rich flag FR at P ₂₈ when the
After setting, the air-fuel ratio of the first cylinder is made rich at P ₂₉ , the routine of this time is ended, and the movement of ΔD ₁ is monitored. In the next routine, if ΔD ₁ is ΔD ₁ ≤r, it means that the knock level will not decrease despite the air-fuel ratio being over-enriched. Therefore, the mechanical vibration is abnormally large at P ₂₉ and the knocking error is incorrect. Or an abnormality indicating that the injector is malfunctioning (for example, a fuel injection amount smaller than a required value is being performed) (hereinafter referred to as abnormality II) is displayed and stored in the memory.

(III) When r <ΔD ₁ <a At this time, it is determined whether or not the transition to the state of r <ΔD ₁ <a is the action result of the air-fuel ratio, that is, the air-fuel ratio is diluted or enriched. To determine. That is, the lean flag FL and the rich flag FR are determined in P ₃₁ and P ₃₂ , respectively. FL = 1
It means that results knocking that lean the air-fuel ratio is changed to the normal correction amount generated when the, low compression ratio P ₃₃ (the case of air leakage is also) or the air-fuel ratio rich An abnormality (hereinafter referred to as abnormality III-1) indicating that the injector is one having a smaller air distribution or a larger injection flow rate than the normal one is displayed and stored in the memory.

Also, since when in P ₃₂ of FR = 1 means that the results knocking was too rich air-fuel ratio is changed to the normal correction amount occurs, a high compression ratio with P ₃₄ (machining mistakes heads )
Alternatively, an abnormality (hereinafter referred to as abnormality III-2) indicating that the air-fuel ratio is lean (the injector has a larger air distribution or a smaller injection flow rate than the normal one) is displayed and stored in the memory.

On the other hand, in the cases other than the above, since it is normal, the routine of this time is ended through P ₃₁ -P ₃₂ without going to P ₃₃ and P ₃₄ .

In this way, by properly determining the imbalance between the cylinders of the ignition correction amount when the ignition timing is feedback-controlled so as to keep the knocking level below a predetermined value, various abnormalities of the engine are individually diagnosed and displayed, Remembered. Therefore, based on this diagnosis result, maintenance of the engine,
The repairability can be greatly improved. Further, in the present embodiment, the physical quantity S can be compared with the lower limit value to determine the abnormality of the sensor signal system.

(Effect) According to the present invention, it is possible to appropriately determine the imbalance between the cylinders of the ignition correction amount when the ignition timing is feedback-controlled so that the knocking level is maintained at a predetermined value or less, and an engine other than the knock detecting means is provided. A remarkable effect is obtained in that various abnormalities of parts, for example, abnormal compression ratio, abnormal air-fuel ratio, misfire, etc. can be specified in detail and an alarm can be issued.

[Brief description of drawings]

FIG. 1 is a basic conceptual diagram of the present invention, FIGS. 2 to 6 are diagrams showing an embodiment of the present invention, FIG. 2 is a circuit configuration diagram thereof, and FIG.
FIG. 1A is a cross-sectional view showing how the cylinder pressure sensor is attached.
FIG. 3 (B) is a plan view of only the in-cylinder pressure sensor, and FIGS. 4 (A) to 4 (F) are waveform diagrams showing signal waveforms of respective parts, and FIG.
FIG. 6 is a flow chart showing a program for performing the abnormality diagnosis, and FIG. 6 is a view showing the relationship between the lower limit value Smin of the physical quantity and the rotation speed N. 12 ... Knock detection means, 13 ... Control unit (ignition timing setting means, setting means, comparison means, determination means), 14 ... Operating state detection means, 15 ... Ignition means, 16 ... Abnormality display lamp (alarm) means).

Claims (1)

[Claims] 1. A knock detecting means for detecting knock vibration generated in an engine, (b) an operating state detecting means for detecting an operating state of the engine, and (c) a basic ignition timing based on the operating state. An ignition timing setting unit that sets an ignition correction amount for each cylinder that corrects the basic ignition timing so that the knock vibration level becomes a predetermined value or less, and corrects the basic ignition timing according to the ignition correction amount, (D) Ignition means for igniting the air-fuel mixture based on the output of the ignition timing setting means, (e) Limit value (advance limit value) of the unbalance of the ignition correction amount between the cylinders toward the advance side, and Setting means for setting a limit value (delay angle limit value) of unbalance to the retard side, and (f) the actual ignition correction amount determined by the ignition timing setting means, the advance limit value and the retard angle. Comparison to compare with limit value (G) When the ignition correction amount is equal to or more than the advance angle limit value, it is determined that the advance angle is excessively advanced. In this case, the air-fuel ratio is controlled in the lean direction to judge the first abnormal pattern if the state of excessive advance does not change, the second abnormal pattern if the state changes, and the retard angle When it is determined that the engine speed is excessive, the air-fuel ratio is controlled in the rich direction to determine the third abnormality pattern if the retarded state does not change, and the fourth abnormality pattern is determined if the state changes. An abnormality diagnosis device for an internal combustion engine, comprising: a determining unit; and (h) an alarm unit that issues an alarm when an abnormality is determined by the determining unit.