JP4247705B2 - In-cylinder pressure detecting device and in-cylinder pressure sensor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an in-cylinder pressure detecting device and an in-cylinder pressure sensor for detecting an in-cylinder pressure of an engine.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, an in-cylinder pressure sensor for detecting an in-cylinder pressure of an engine includes an annular (tubular) piezoelectric element (see, for example, Patent Document 1). This type of in-cylinder pressure sensor includes a diaphragm that receives in-cylinder pressure and a transmission member that transmits the in-cylinder pressure received by the diaphragm to the piezoelectric element. A preload is applied to the piezoelectric element by a fixing screw or the like. It is common that In addition, as a piezoelectric element used for detecting the in-cylinder pressure, an element formed in an annular shape (washer shape) so as to be disposed between the cylinder head and the spark plug is also known (for example, Patent Documents). 2).
[0003]
Furthermore, a cylinder pressure sensor that includes a semiconductor element instead of a piezoelectric element is also known. In this case, a semiconductor element having a characteristic that the resistance value changes according to the applied pressure is employed. This type of in-cylinder pressure sensor generally also includes a diaphragm that receives the in-cylinder pressure and a transmission member that transmits the in-cylinder pressure received by the diaphragm to the semiconductor element. An in-cylinder pressure sensor is also known in which an amplifier is incorporated in a housing that houses a semiconductor element or the like in order to amplify the output of the semiconductor element (see, for example, Patent Document 3).
[0004]
[Patent Document 1]
JP 7-049283 A
[Patent Document 2]
Japanese Utility Model Publication No. 5-045422
[Patent Document 3]
JP-A-5-126667
[0005]
[Problems to be solved by the invention]
Here, the dynamic range (detectable pressure range) of the device that detects the in-cylinder pressure needs to correspond to a wide range of about 0 to 20 MPa, for example. However, as the dynamic range is increased, the resolution decreases. For this reason, even if the conventional in-cylinder pressure sensor as described above is used, it is difficult to detect the in-cylinder pressure with high accuracy. That is, it is not easy to make both the dynamic range and the resolution compatible in the conventional in-cylinder pressure sensor, and no in-cylinder pressure detecting device that satisfies both the conditions has been proposed.
[0006]
Therefore, an object of the present invention is to provide an in-cylinder pressure detection device and an in-cylinder pressure sensor that have a wide dynamic range and high resolution and can detect a cylinder pressure over a wide range with high accuracy.
[0007]
[Means for Solving the Problems]
An in-cylinder pressure detecting device according to the present invention is an in-cylinder pressure detecting device for detecting an in-cylinder pressure of an engine. An in-cylinder pressure sensor for detecting an in-cylinder pressure based on a change in resistance value according to an applied pressure; A power source for supplying a current to the internal pressure sensor and a current value setting means for changing the value of the current supplied from the power source to the in-cylinder pressure sensor are provided.
[0008]
In this in-cylinder pressure detecting device, when detecting the in-cylinder pressure, a current is supplied from a power source to an in-cylinder pressure sensor including a semiconductor element and the like. As a result, the in-cylinder pressure sensor outputs a voltage signal corresponding to the in-cylinder pressure based on the resistance value of the semiconductor element or the like changed according to the in-cylinder pressure and the current value from the power source. At this time, in the in-cylinder pressure detecting device according to the present invention, the value of the current supplied to the in-cylinder pressure sensor is appropriately changed by the current value setting means.
[0009]
If the current supplied to the in-cylinder pressure sensor is set to a larger value by the current value setting means, the output of the in-cylinder pressure sensor is amplified according to the value of the current from the power source. Therefore, if this in-cylinder pressure detecting device is used, even if the in-cylinder pressure to be detected is relatively low, the in-cylinder pressure can be set by appropriately setting the value of the current supplied to the in-cylinder pressure sensor. It is possible to sufficiently identify the fluctuation range (pulsation). As a result, according to the in-cylinder pressure detecting device of the present invention, it is possible to improve the resolution satisfactorily while setting a wide dynamic range of the in-cylinder pressure sensor, and to detect in-cylinder pressure over a wide range with extremely high accuracy. Can do.
[0010]
Further, in this in-cylinder pressure detecting device, the power source, the current value setting means and the like can be easily separated from the in-cylinder pressure sensor, so that the in-cylinder pressure sensor which is an element disposed close to the engine is configured to be extremely compact. It becomes possible. As a result, it is possible to prevent the in-cylinder pressure sensor and the ignition device and the fuel injection device from interfering with each other when the in-cylinder pressure detection device is installed in the engine. The presence of the in-cylinder pressure sensor increases the diameter of the valve. Can be easily avoided.
[0011]
Further, the current value setting means preferably sets the value of the current supplied from the power source to the in-cylinder pressure sensor based on the crank angle of the engine.
[0012]
Generally, the level of in-cylinder pressure during engine operation can be grasped by monitoring the crank angle. Therefore, by adopting such a configuration, it is possible to change the value of the current supplied from the power source to the in-cylinder pressure sensor after accurately grasping the timing at which the in-cylinder pressure becomes relatively low.
[0013]
The current value setting means sets the value of the current supplied from the power source to the in-cylinder pressure sensor so that the output of the in-cylinder pressure sensor is amplified in the exhaust stroke and the intake stroke as compared with the compression stroke and the expansion stroke. preferable.
[0014]
In general, the in-cylinder pressure of the engine increases in the compression stroke and the expansion stroke, but decreases in the exhaust stroke and the intake stroke. Accordingly, by setting the value of the current to the in-cylinder pressure sensor so that the output of the in-cylinder pressure sensor is amplified in the exhaust stroke and the intake stroke as compared with the compression stroke and the expansion stroke, the in-cylinder pressure during engine operation is set. Detection accuracy can be improved.
[0015]
Furthermore, it is preferable that the current value setting means can set the value of the current supplied from the power source to the in-cylinder pressure sensor in accordance with the engine load.
[0016]
During the operation of the engine, the in-cylinder pressure also changes depending on the load factor of the engine. For example, the maximum value of the in-cylinder pressure at the time of low load is lower than that at the time of high load. Therefore, by changing the value of the current supplied from the power source to the in-cylinder pressure sensor in accordance with the engine load, the output of the in-cylinder pressure sensor can be amplified at low loads. The pressure detection accuracy can be further improved.
[0017]
An in-cylinder pressure sensor according to the present invention includes a plurality of in-cylinder pressure detecting means capable of detecting the in-cylinder pressure in the in-cylinder pressure sensor used for detecting the in-cylinder pressure of the engine. The pressure detection ranges are different from each other.
[0018]
This in-cylinder pressure sensor includes a plurality of in-cylinder pressure detecting means such as semiconductor elements and piezoelectric elements, and the plurality of in-cylinder pressure detecting means have different pressure detection ranges. Therefore, in this in-cylinder pressure sensor, the assumed range of in-cylinder pressure can be divided into a plurality of in-cylinder pressure detecting means in advance. As a result, the resolution can be set to a practically good range while ensuring a sufficiently wide dynamic range of the entire sensor, so that a wide range of in-cylinder pressure can be detected with extremely high accuracy.
[0019]
In this case, the plurality of in-cylinder pressure detecting means include a detecting means for mainly detecting the in-cylinder pressure in the compression stroke and the expansion stroke, and a detecting means for detecting the in-cylinder pressure mainly in the exhaust stroke and the intake stroke. Preferably it is included.
[0020]
The plurality of in-cylinder pressure detecting means are preferably integrated with each other. Thereby, the mounting property (attachability) of the in-cylinder pressure sensor to the engine can be improved.
[0021]
Furthermore, the plurality of in-cylinder pressure detecting means may be arranged along a direction substantially orthogonal to the respective pressure receiving surfaces, and the plurality of in-cylinder pressure detecting means correspond to the sensor pressure receiving surfaces facing the inside of the cylinder. Detection means and detection means corresponding to a sensor pressure-receiving surface that contacts a part of the engine may be included. Furthermore, the pressure receiving surface (sensor pressure receiving surface) of the in-cylinder pressure sensor corresponding to each of the plurality of in-cylinder pressure detecting means may be included in substantially the same plane.
[0022]
Further, at least one of the plurality of in-cylinder pressure detecting means is a piezoelectric element, and it is preferable to further include a spacer that is disposed so as to contact the piezoelectric element and concentrates stress on the piezoelectric element. By adopting such a configuration, the sensitivity of the piezoelectric element can be easily and reliably improved, and a preliminary load on the piezoelectric element can be easily and freely set.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of an in-cylinder pressure detecting device and an in-cylinder pressure sensor according to the present invention will be described in detail with reference to the drawings.
[0024]
[First Embodiment]
FIG. 1 is a block diagram showing an in-cylinder pressure detecting device according to the present invention, and FIG. 2 is an enlarged partial sectional view showing a part of the in-cylinder pressure detecting device of FIG. The in-cylinder pressure detection device 1 shown in these drawings is applicable to various engines such as a multi-cylinder gasoline engine, and is a cylinder that detects the in-cylinder pressure in the combustion chamber CR (see FIG. 2) of the engine. An internal pressure sensor 2 and a power source 3 for supplying current to the in-cylinder pressure sensor 2 are included. In FIG. 1, only one in-cylinder pressure sensor 2 is shown for easy understanding.
[0025]
In the present embodiment, a so-called semiconductor pressure sensor is employed as the in-cylinder pressure sensor 2, and the in-cylinder pressure sensor 2 is a semiconductor element (in-cylinder pressure detecting means) having a characteristic that the resistance value changes according to the applied pressure. ) 20 and a casing 21 formed in a cylindrical shape with stainless steel or the like. The semiconductor element 20 includes, for example, a silicon substrate and four piezoresistors formed by a diffusion technique or the like so as to form a bridge on the substrate. As shown in FIG. 2, the semiconductor element 20 is attached to an internal fixing member 22 disposed inside the housing 21 and is housed inside the housing 21. The two lead wires of the semiconductor element 20 are inserted through holes formed in the internal fixing member 22 and are connected to terminals mounted on a connector portion (not shown).
[0026]
On the outer peripheral surface of the housing 21, a male screw is formed that is screwed into a hole of the cylinder head CH of the engine. A diaphragm 23 is fixed to the tip of the housing 21. And between the semiconductor element 20 and the diaphragm 23, the heat insulator (transmission member) 24, the hemispherical member 25, and the glass block 26 are arrange | positioned in an order from the diaphragm 23 side. The cylinder pressure sensor 2 is attached to the hole of the cylinder head CH so that the diaphragm 23 faces the inside of the combustion chamber CR for each cylinder of the engine, and the surface of the diaphragm 23 on the combustion chamber CR side is the cylinder pressure sensor 2. Pressure receiving surface (sensor pressure receiving surface).
[0027]
When the in-cylinder pressure in the combustion chamber CR acts on the diaphragm 23, the in-cylinder pressure is transmitted to the semiconductor element 20 through the heat insulator 24, the hemispherical member 25, and the glass block 26. When a current is supplied to the in-cylinder pressure sensor 2 from the power source 3, the in-cylinder pressure sensor 2 (semiconductor element 20) determines the resistance value changed according to the in-cylinder pressure in the combustion chamber CR and the current value from the power source 3. Based on the above, a voltage signal Vout corresponding to the in-cylinder pressure is output. The output of the in-cylinder pressure sensor 2 is taken out via an operational amplifier 4 as shown in FIG. During operation of the engine, heat in the combustion chamber CR is applied to the diaphragm 23, but heat transfer from the diaphragm 23 to the semiconductor element 20 is blocked by the heat insulator 24.
[0028]
On the other hand, in the present embodiment, the power source 3 that supplies current to the above-described in-cylinder pressure sensor 2 is configured as a constant voltage power source, and one terminal of the semiconductor element 20 constituting the in-cylinder pressure sensor 2 has a constant value. A voltage Vc is applied. A variable resistor 5 is connected in series to the ground side terminal of the semiconductor element 20 constituting the in-cylinder pressure sensor 2. The variable resistor 5 includes a plurality of (in this embodiment, three) resistors Rf connected in parallel.₀, Rf₁And Rf₂And transistor Tr₁And Tr₂Including. Transistor Tr₁Is the input terminal of the variable resistor 5 and the resistor Rf₁While the transistor Tr₂Is the input terminal of the variable resistor 5 and the resistor Rf₂And both function as switching elements that change the resistance value R of the variable resistor 5.
[0029]
That is, the transistor Tr₁And Tr₂When both are turned off, the total resistance value R of the variable resistor 5 becomes maximum,
R = Rf₀
It becomes. The transistor Tr₁Is turned on while the transistor Tr₂Is turned off, the total resistance value R of the variable resistor 5 is
R = Rf₀・ Rf₁/ (Rf₀+ Rf₁)
It becomes. Furthermore, the transistor Tr₁Is turned off while the transistor Tr₂Is turned on, the total resistance value R of the variable resistor 5 is
R = Rf₀・ Rf₂/ (Rf₀+ Rf₂)
It becomes.
The transistor Tr₁And transistor Tr₂When both are turned on, the total resistance value R of the variable resistor 5 is minimized,
R = Rf₀・ Rf₁・ Rf₂/ (Rf₀・ Rf₁+ Rf₁・ Rf₂+ Rf₂・ Rf₀)
It becomes. The number of resistors of the variable resistor 5 and each resistor Rf₀, Rf₁And Rf₂The value of can be arbitrarily determined.
[0030]
Such a setting of the total resistance value R of the variable resistor 5, that is, the transistor Tr₁And Tr₂The on / off control is performed by the control unit 10 included in the in-cylinder pressure detecting device 1. The control unit 10 includes a CPU, a ROM, a RAM, a storage device, etc. (not shown) and a transistor Tr of the variable resistor 5.₁And Tr₂And a pulse generator (not shown) for applying a pulse voltage signal to the gate. The control unit 10 includes a transistor Tr₁And Tr₂Is turned on / off as appropriate to change the total resistance value R of the variable resistor 5, thereby setting the value of the current supplied to the in-cylinder pressure sensor 2 (semiconductor element 20). That is, the variable resistor 5 and the control unit 10 function as a current value setting means for changing the value of the current supplied from the power source 3 to the in-cylinder pressure sensor 2.
[0031]
Further, as shown in FIG. 1, a crank angle sensor 6 and an air flow meter 7 provided for the engine are connected to the control unit 10. Further, when the engine to which the in-cylinder pressure detecting device 1 is applied is provided with a variable valve timing mechanism, the cam angle sensor 8 included in the variable valve timing mechanism is connected to the control unit 10.
[0032]
Next, the operation of the above-described in-cylinder pressure detecting device 1 will be described.
[0033]
While the engine is operating, the crank angle sensor 6 detects the crank angle of the engine for each cylinder and gives a signal indicating the crank angle to the control unit 10. Based on the signal from the crank angle sensor 6, the control unit 10 obtains the timing at which the piston is located at the bottom dead center BDC and the timing at which the piston is located at the top dead center TDC for each cylinder. It is determined whether the stroke is in expansion or exhaust.
[0034]
Here, as shown in FIG. 3, the in-cylinder pressure generally increases in the compression stroke and the expansion stroke, but decreases in the exhaust stroke and the intake stroke (see the two-dot chain line in FIG. 3), and the exhaust stroke and the intake stroke. Then, pulsation of in-cylinder pressure is also observed. Therefore, it is possible to accurately grasp the timing at which the in-cylinder pressure is relatively lowered during engine operation by determining whether each piston is in the intake, compression, expansion, or exhaust stroke based on the crank angle. Can do.
[0035]
The control unit 10 determines whether each piston is in an intake stroke, compression stroke, expansion stroke, or exhaust stroke, and sets the current supplied from the power source 3 to the in-cylinder pressure sensor 2 in accordance with the determined stroke. In the case of this embodiment, if the resistance value of the semiconductor element 20 is Rs, the value Is of the current flowing through the semiconductor element 20 of the in-cylinder pressure sensor 2 is
Is = Vc / (Rs + R)
The output Vout of the in-cylinder pressure sensor 2 (semiconductor element 20) is
Vout = Rs · Is = Vc · Rs / (Rs + R)
It becomes. For this reason, the control unit 10 determines, for example, that the transistor Tr of the variable resistor 5 when each piston is in the exhaust stroke and the intake stroke.₁And Tr₂By turning on one or all of these, the total resistance value R of the variable resistor 5 is set to a smaller value than the compression stroke and the intake stroke.
[0036]
As a result, in the in-cylinder pressure detecting device 1, the current supplied to the in-cylinder pressure sensor 2 (semiconductor element 20) is set to a larger value in the exhaust stroke and the intake stroke than in the compression stroke and the expansion stroke. Therefore, in the exhaust stroke and the intake stroke, as indicated by a solid line in FIG. 3, the output Vout of the in-cylinder pressure sensor 2 constantly supplies a constant current from the power source 3 to the in-cylinder pressure sensor 2 (in FIG. 3). It is amplified in comparison with the two-dot chain line).
[0037]
As a result, if the in-cylinder pressure detecting device 1 is used, even if the in-cylinder pressure to be detected becomes relatively low, such as in the exhaust stroke and the intake stroke, the value of the current supplied to the in-cylinder pressure sensor 2. By appropriately setting the value, it is possible to sufficiently identify the pulsation of the in-cylinder pressure in the exhaust stroke and the intake stroke. Therefore, according to the in-cylinder pressure detecting device 1, it is possible to improve the resolution satisfactorily while setting a wide dynamic range of the in-cylinder pressure sensor 2, and it is possible to detect the in-cylinder pressure over a wide range with extremely high accuracy. .
[0038]
Further, in the in-cylinder pressure detecting device 1, the power source 3, the operational amplifier 4, the variable resistor 5, the control unit 10 and the like can be easily separated from the in-cylinder pressure sensor 2. Therefore, the in-cylinder pressure sensor 2 itself, which is an element disposed close to the engine, can be configured extremely compactly. As a result, it is possible to prevent the in-cylinder pressure sensor 2 from interfering with the ignition device or the fuel injection device when the in-cylinder pressure detecting device 1 is installed in the engine. It is possible to easily avoid a situation where the increase in diameter is hindered.
[0039]
By the way, the level of the in-cylinder pressure of the engine can be basically grasped from the crank angle. However, during the operation of the engine, the in-cylinder pressure also changes depending on the load factor of the engine. The maximum value of in-cylinder pressure is lower than that at high load. For this reason, unless any countermeasure is taken, the output Vout of the in-cylinder pressure sensor at the time of low load also decreases as compared with that at the time of high load, as indicated by a broken line in FIG. In view of this point, the control unit 10 of the in-cylinder pressure detecting device 1 is configured to change (correct) the value of the current supplied from the power source 3 to the in-cylinder pressure sensor 2 in accordance with the engine load. .
[0040]
That is, while the engine is operating, the control unit 10 obtains the load factor of the engine from the air filling rate in each combustion chamber CR based on the signal received from the air flow meter 7. Then, the control unit 10 is based on the obtained engine load factor, a map showing the relationship between the engine load factor and the value of the current supplied to the in-cylinder pressure sensor 2 as shown in FIG. The total resistance value R of the variable resistor 5 is changed to adjust the current value to the in-cylinder pressure sensor 2.
[0041]
The current value setting map shown in FIG. 5 reduces the value of the current from the power source 3 to the in-cylinder pressure sensor 2 stepwise with a predetermined width as the engine load factor increases, and decreases the engine load factor. It was created so as to increase step by step. As a result, in the in-cylinder pressure detecting device 1, as indicated by the solid line in FIG. 4, the output Vout of the in-cylinder pressure sensor is amplified at the time of low load. In this way, the accuracy of detecting the in-cylinder pressure during engine operation is further improved by changing the value of the current supplied from the power source 3 to the in-cylinder pressure sensor 2 while also taking into account the engine load factor. Is possible.
[0042]
Further, when the variable valve timing mechanism (VVT) is provided for the engine, the timing of changing the value of the current supplied from the power source 3 to the in-cylinder pressure sensor 2 is the overlap between the exhaust valve and the intake valve ( It is preferable to correct based on the advance angle. That is, when the opening timing of the intake valve is advanced by the variable valve timing mechanism, the end timing of the intake stroke changes according to the overlap between the exhaust valve and the intake valve, and the compression stroke and the expansion stroke are accordingly changed. The end timing will also change. Therefore, in such a case, in order to improve the detection accuracy of the in-cylinder pressure by the in-cylinder pressure sensor 2, it is necessary to consider the overlap between the exhaust valve and the intake valve.
[0043]
For this reason, when the in-cylinder pressure detecting device 1 is applied to an engine having a variable valve timing mechanism, as shown in FIG. 1, the cam angle sensor included in the variable valve timing mechanism with respect to the control unit 10. The signal from 8 is given. Then, the control unit 10 obtains the advance angle between the exhaust valve and the intake valve based on the signal from the cam angle sensor 8, and as shown in FIG. The timing of switching (increasing) the total resistance value R of the variable resistor 5 (timing of decreasing the value of the current supplied from the power source 3 to the in-cylinder pressure sensor 2) as compared with the non-operating time (see the broken line in FIG. 6). Advance. As a result, the accuracy of detecting the in-cylinder pressure during the operation of the engine having the variable valve timing mechanism can be further improved.
[0044]
FIG. 7 is a schematic configuration diagram showing a modification of the first embodiment of the in-cylinder pressure detecting device according to the present invention. In the in-cylinder pressure detecting device 1A shown in the figure, a constant current power source capable of supplying a constant current Ic is employed as the power source 3 for supplying current to the in-cylinder pressure sensor 2. In this case, the variable resistor 5 is connected in parallel with the in-cylinder pressure sensor 2 and controlled by the control unit 10A. When the control unit 10A determines that the piston is in the exhaust stroke and the intake stroke based on the signal from the crank angle sensor 6, the total resistance value of the variable resistor 5 is amplified so that the output Vout of the in-cylinder pressure sensor 2 is amplified. R is set to a large value compared to the compression and expansion strokes.
[0045]
Further, like the in-cylinder pressure detection device 1B shown in FIG. 8, the D / A is connected to the control unit 10B (or included in the control unit 10B) as a power source for supplying current to the in-cylinder pressure sensor 2. A converter 9 may be employed. In this case, the control unit 10B determines a current value to be supplied to the in-cylinder pressure sensor 2 based on the crank angle, and provides a digital signal indicating the current value to the D / A converter 9. The D / A converter 9 as a power source converts the digital signal from the control unit 10B into an analog signal (current) and applies the analog signal to the in-cylinder pressure sensor 2.
[0046]
Even if these configurations are adopted, the value of the current supplied to the in-cylinder pressure sensor 2 can be appropriately changed. Also in these in-cylinder pressure detection devices 1A and 1B, it is preferable that the value of the current supplied from the power source 3 or the D / A converter 9 to the in-cylinder pressure sensor 2 is adjusted according to the engine load. Further, when these in-cylinder pressure detection devices 1A and 1B are applied to an engine having a variable valve timing mechanism, the timing at which the value of the current supplied to the in-cylinder pressure sensor 2 is changed is an excess between the exhaust valve and the intake valve. It is preferable to correct based on the lap (advance angle).
[0047]
[Second Embodiment]
FIG. 9 is an enlarged partial cross-sectional view showing a main part of an in-cylinder pressure sensor according to the present invention. The in-cylinder pressure sensor 2A shown in the figure is basically similar to the in-cylinder pressure sensor 2 of FIG. 2, but has a plurality (two bodies) of semiconductor elements 20a and 20b as means for detecting the in-cylinder pressure. This is different from the in-cylinder pressure sensor 2 of FIG. Of the two semiconductor elements 20 a and 20 b, the first semiconductor element 20 a is attached to the internal fixing member 22 </ b> A disposed inside the housing 21. The second semiconductor element 20b is fixed to the pressure receiving surface (the lower surface in FIG. 9) of the first semiconductor element 20a via the glass block 26a.
[0048]
Thus, in the in-cylinder pressure sensor 2A, the two semiconductor elements (in-cylinder pressure detecting means) 20a and 20b are arranged in a direction substantially orthogonal to the respective pressure receiving surfaces (a direction substantially orthogonal to the surface of the diaphragm 23). And integrated with each other. As a result, the outer diameter of the casing 21 can be reduced, the in-cylinder pressure sensor 2A can be made compact, and the mountability (attachability) to the engine can be improved. The lead wires of the respective semiconductor elements 20a and 20b are respectively inserted into the corresponding hole portions of the internal fixing member 22A and are connected to terminals mounted on a connector portion (not shown). Further, between the second semiconductor element 20b and the diaphragm 23, a heat insulator 24, a hemispherical member 25, and a glass block 26b are sequentially arranged.
[0049]
Here, the first semiconductor element 20a and the second semiconductor element 20b included in the in-cylinder pressure sensor 2A have different pressure detection ranges. That is, the first semiconductor element (high-pressure side semiconductor element) 20a is mainly used to detect a high in-cylinder pressure (for example, approximately 10 to 20 MPa) in the compression stroke and the expansion stroke, and from the first semiconductor element 20a. The second semiconductor element (low pressure side semiconductor element) 20b disposed on the combustion chamber CR side is mainly used to detect a low in-cylinder pressure (for example, approximately 0 to 300 kPa) in the exhaust stroke and the intake stroke.
[0050]
The in-cylinder pressure sensor 2A configured as described above is attached to the hole of the cylinder head CH so that the diaphragm 23 faces the inside of the combustion chamber CR. When a current is supplied to the semiconductor elements 20a and 20b from a power source (not shown) and the in-cylinder pressure in the combustion chamber CR acts on the diaphragm 23, either one of the semiconductor elements 20a and 20b becomes a cylinder in the combustion chamber CR. Based on the resistance value changed according to the internal pressure and the value of the supplied current, a voltage signal corresponding to the detected in-cylinder pressure is output.
[0051]
That is, the in-cylinder pressure acting on the diaphragm 23 is transmitted to the low-pressure side semiconductor element 20b via the heat insulator 24, the hemispherical member 25 and the glass block 26b, and further, the high-pressure side semiconductor element via the glass block 26a. 20a, but when the in-cylinder pressure is low as in the exhaust stroke or the intake stroke (when the in-cylinder pressure is within the detection range of the semiconductor element 20b on the low pressure side), the voltage signal corresponding to the in-cylinder pressure is Then, it is taken out from the semiconductor element 20b on the low pressure side. On the other hand, when the in-cylinder pressure is high as in the compression stroke or the expansion stroke (when the in-cylinder pressure is within the detection range of the semiconductor element 20a on the high pressure side), the voltage signal corresponding to the in-cylinder pressure is It is taken out from the element 20a.
[0052]
In this way, in the in-cylinder pressure sensor 2A, the plurality of semiconductor elements (in-cylinder pressure detecting means) 20a and 20b have different pressure detection ranges, so that the assumed in-cylinder pressure range is set to the plurality of semiconductor elements 20a. And 20b can be divided and assigned in advance. Therefore, since the resolution can be set to a practically good range while ensuring a sufficiently wide dynamic range of the entire sensor, it is possible to detect in-cylinder pressure over a wide range with extremely high accuracy.
[0053]
The configuration described in relation to the first embodiment is applied to the in-cylinder pressure sensor 2A according to the second embodiment, and supplied to one or both of the semiconductor elements 20a and 20b of the in-cylinder pressure sensor 2A. The current value may be changed based on the crank angle or the load factor of the engine. Thereby, the detection accuracy of the in-cylinder pressure by the in-cylinder pressure sensor 2A can be further improved. When the in-cylinder pressure sensor 2A is applied to an engine having a variable valve timing mechanism, the timing for changing the value of the current supplied to the in-cylinder pressure sensor 2A is corrected based on the overlap between the exhaust valve and the intake valve. It is preferred if
[0054]
FIG. 10 is an enlarged partial cross-sectional view of a main part showing a modification of the in-cylinder pressure sensor according to the present invention. The in-cylinder pressure sensor 30 shown in the figure has a plurality of (two in this example) in-cylinder pressure detecting means, and the resistance value corresponding to the applied pressure changes as the two in-cylinder pressure detecting means. A semiconductor element 31 having such characteristics and a piezoelectric element 32 that generates an electrostatic charge according to an applied pressure are employed. Further, the semiconductor element 31 and the piezoelectric element 32 have different pressure detection ranges, and the semiconductor element 31 is mainly used for detecting a low in-cylinder pressure in the exhaust stroke and the intake stroke. Is mainly used to detect a high in-cylinder pressure in the compression stroke and the expansion stroke.
[0055]
The semiconductor element 31 is attached to an internal fixing member (not shown) disposed inside the housing 33. A diaphragm 34 is fixed to the front end of the housing 33, and the surface of the diaphragm 34 on the combustion chamber CR side serves as a first pressure receiving surface (sensor pressure receiving surface) of the in-cylinder pressure sensor 30. And between the semiconductor element 31 and the diaphragm 34, the heat insulator 35, the hemispherical member 36, and the glass block 37 are arrange | positioned in order.
[0056]
On the other hand, as the piezoelectric element 32, an element formed in an annular shape (washer shape) so as to be mounted on the outer periphery of the housing 33 is employed. By fixing the piezoelectric element 32 to the outer periphery of the casing 33, the piezoelectric element 32 and the semiconductor element 31 in the casing 33 are in a direction substantially orthogonal to the respective pressure receiving surfaces (a direction orthogonal to the surface of the diaphragm 34). They are integrated with each other in a line. Thereby, the mountability with respect to the engine of the in-cylinder pressure sensor 30 can be improved. Further, the pressure receiving surface (the lower surface in FIG. 10) of the piezoelectric element 32 is in contact with the surface of the stepped portion CHS formed in the cylinder head CH, and the pressure receiving surface of the piezoelectric element 32 is the second pressure receiving surface of the in-cylinder pressure sensor 30. (Sensor pressure receiving surface). A preliminary load is applied to the piezoelectric element 32 by a tightening member 38 screwed into the cylinder head CH.
[0057]
In the in-cylinder pressure sensor 30 configured as described above, the in-cylinder pressure acting on the diaphragm 34 that defines the first sensor pressure-receiving surface is applied to the semiconductor element 31 via the heat insulator 35, the hemispherical member 36, and the glass block 37. It is transmitted to the piezoelectric element 32 through the cylinder head CH constituting the engine. When the in-cylinder pressure is low as in the exhaust stroke or the intake stroke (when the in-cylinder pressure is within the detection range of the semiconductor element 31), a voltage signal corresponding to the in-cylinder pressure is extracted from the semiconductor element 31. On the other hand, when the in-cylinder pressure is high as in the compression stroke or the expansion stroke (when the in-cylinder pressure is within the detection range of the piezoelectric element 32), a signal corresponding to the in-cylinder pressure is extracted from the piezoelectric element 32.
[0058]
As described above, in the in-cylinder pressure sensor 30, the semiconductor element 31 and the piezoelectric element 32 have different pressure detection ranges. Therefore, the assumed in-cylinder pressure range is changed between the semiconductor element 31 and the piezoelectric element 32. It can be divided and assigned in advance. Therefore, since the resolution can be set to a practically good range while ensuring a sufficiently wide dynamic range of the entire sensor, it is possible to detect in-cylinder pressure over a wide range with extremely high accuracy.
[0059]
The semiconductor element 31 of the in-cylinder pressure sensor 30 is supplied with a current from a power source (not shown). The value of the current supplied to the semiconductor element 31 is changed based on the crank angle and the engine load factor. Also good. Thereby, the detection accuracy of the in-cylinder pressure by the in-cylinder pressure sensor 30 can be further improved. When the in-cylinder pressure sensor 30 is applied to an engine having a variable valve timing mechanism, the timing for changing the value of the current supplied to the semiconductor element 31 is corrected based on the overlap between the exhaust valve and the intake valve. Good.
[0060]
In the in-cylinder pressure sensor 30 shown in FIG. 10, the piezoelectric element 32 is included as one of the in-cylinder pressure detecting means. In such a case, as shown in FIG. 39 is preferably provided. The spacer 39 in FIG. 11 is disposed so as to contact the piezoelectric element 32, and concentrates stress on the piezoelectric element 32. As shown in FIG. 11, the spacer 39 may be formed as an annular member on a flat plate, or may be integrated with the cylinder head CH or the like or the fastening member 38.
[0061]
In the in-cylinder pressure sensor 30 </ b> A shown in FIG. 11, the spacer 39 is disposed between the cylinder head CH and the piezoelectric element 32 and between the tightening member 38 and the piezoelectric element 32. Thus, by arranging the spacer 39 between the cylinder head CH and the piezoelectric element 32, the sensitivity of the piezoelectric element 32 can be improved easily and reliably. Further, by arranging the spacer 39 between the tightening member 38 and the piezoelectric element 32, a preliminary load on the piezoelectric element 32 can be set easily and freely.
[0062]
In the in-cylinder pressure sensor 30A shown in FIG. 11, a flange 33f that abuts the stepped portion CHS of the cylinder head CH and receives the piezoelectric element 32 is fixed to the housing 33 that accommodates the semiconductor element 31. 11 is a second pressure receiving surface (sensor pressure receiving surface) of the in-cylinder pressure sensor 30A. Under such a configuration, the spacer 39 disposed between the cylinder head CH and the piezoelectric element 32 may be integrated with the flange 33f.
[0063]
In the in-cylinder pressure sensor 30 in FIG. 10 and the in-cylinder pressure sensor 30A in FIG. 11, the semiconductor element 31 and the piezoelectric element 32 are combined as the in-cylinder pressure detecting means. However, like the in-cylinder pressure sensor 30B shown in FIG. As the in-cylinder pressure detecting means, a plurality (two bodies) of piezoelectric elements 32a and 32b having different pressure detection ranges may be used. In this case, the in-cylinder pressure is transmitted to the piezoelectric elements 32 a and 32 b by the transmission member 40. The transmission member 40 includes a main body 41 having one end facing the inside of the combustion chamber CR, and flanges 42a and 42b fixed to the main body 41. In this example, the piezoelectric element 32a sandwiched between the outer flange 42a and the fastening member 38B is used to detect a low in-cylinder pressure, and is sandwiched between the outer flange 42a and the flange 42b on the combustion chamber CR side. The piezoelectric element 32b positioned on the combustion chamber CR side is used for detecting a high in-cylinder pressure. The tightening member 38B is formed in a bottomed cylindrical shape that can accommodate both the piezoelectric elements 32a and 32b.
[0064]
Also with the in-cylinder pressure sensor 30B configured in this way, it is possible to detect in-cylinder pressure over a wide range with extremely high accuracy. In addition, when only a piezoelectric element is used as a plurality of in-cylinder pressure detecting means like the in-cylinder pressure sensor 30B, each piezoelectric element can be used for improving the sensitivity of the piezoelectric element and facilitating setting of a preload for the piezoelectric element. It is effective to provide a spacer 39 for the elements 32a and 32b. As the transmission member 40, a heater housing of a glow plug or an insulator of a spark plug may be used.
[0065]
FIG. 13 is an enlarged partial cross-sectional view of a main part showing another modification of the in-cylinder pressure sensor according to the present invention. The in-cylinder pressure sensor 50 shown in the figure has a configuration substantially equal to a configuration in which a plurality (two bodies) of semiconductor pressure sensors having different pressure detection ranges are aligned in parallel (lateral direction) and integrated. That is, two diaphragms 52 a and 52 b are attached to the tip of the casing 51 of the in-cylinder pressure sensor 50. The diaphragms 52a and 52b are attached to the casing 51 so that their outer surfaces (surfaces on the combustion chamber side) are included in the same plane. The outer surfaces of the diaphragms 52a and 52b are pressure receiving surfaces of the in-cylinder pressure sensor 50, respectively. (Sensor pressure receiving surface).
[0066]
In the cylinder pressure sensor 50, semiconductor elements 53a and 53b having different pressure detection ranges are provided for the diaphragms 52a and 52b. Each of the semiconductor elements 53a and 53b is attached to an internal fixing member 54 disposed inside the housing 51, and heat is applied between the semiconductor element 53a and the diaphragm 52a and between the semiconductor element 53a and the diaphragm 52a. An insulator 55, a hemispherical member 56, and a glass block 57 are arranged in order.
[0067]
The in-cylinder pressure sensor 50 configured in this way also has a plurality of semiconductor elements (in-cylinder pressure detecting means) 53a and 53b having pressure detection ranges different from each other. The elements 53a and 53b can be divided and held in advance. Therefore, since the resolution can be set to a practically good range while ensuring a sufficiently wide dynamic range of the entire sensor, it is possible to detect in-cylinder pressure over a wide range with extremely high accuracy.
[0068]
Further, instead of using a plurality of semiconductor elements as in-cylinder pressure detecting means as in the in-cylinder pressure sensor 50 in FIG. 13, at least one of in-cylinder pressure detecting means as in the in-cylinder pressure sensor 50A shown in FIG. As an example, an optical fiber sensor 58 may be used. In this case, the optical fiber sensor 58 includes a light emitting element and a light receiving element (not shown), detects the displacement of the diaphragm 52b according to the in-cylinder pressure, and outputs a signal according to the in-cylinder pressure. The in-cylinder pressure sensor 50A configured as described above can also detect the in-cylinder pressure over a wide range with extremely high accuracy.
[0069]
The semiconductor elements 53a and 53b of the in-cylinder pressure sensors 50 and 50A are supplied with a current from a power source (not shown). The value of the current supplied to the semiconductor elements 53a and 53b is determined based on the crank angle and the engine load factor. You may change based on. Thereby, the detection accuracy of the in-cylinder pressure by the in-cylinder pressure sensors 50 and 50A can be further improved. Further, when the in-cylinder pressure sensors 50 and 50A are applied to an engine having a variable valve timing mechanism, the timing for changing the value of the current supplied to the semiconductor elements 53a and 53b is the overlap between the exhaust valve and the intake valve. It may be corrected based on this.
[0070]
【The invention's effect】
As described above, according to the present invention, it is possible to improve the resolution satisfactorily while widening the dynamic range of the in-cylinder pressure detecting device and the in-cylinder pressure sensor, and the cylinder pressure over a wide range is highly accurate. Detection is possible.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing an in-cylinder pressure detecting device according to the present invention.
2 is an enlarged partial cross-sectional view of an in-cylinder pressure sensor showing a part of the in-cylinder pressure detecting device of FIG. 1; FIG.
FIG. 3 is a graph for explaining the operation of the in-cylinder pressure detecting device of FIG. 1;
4 is a graph for explaining the operation of the in-cylinder pressure detecting device of FIG. 1; FIG.
5 is a graph for explaining the operation of the in-cylinder pressure detecting device of FIG. 1; FIG.
6 is a graph for explaining the operation of the in-cylinder pressure detecting device of FIG. 1; FIG.
FIG. 7 is a schematic configuration diagram showing a modification of the in-cylinder pressure detecting device according to the present invention.
FIG. 8 is a schematic configuration diagram showing another modification of the in-cylinder pressure detecting device according to the present invention.
FIG. 9 is an enlarged fragmentary sectional view showing a main part of an in-cylinder pressure sensor according to the present invention.
FIG. 10 is an enlarged partial cross-sectional view of a main part showing a modification of the in-cylinder pressure sensor according to the present invention.
FIG. 11 is an enlarged partial cross-sectional view of a main part showing a modification of the in-cylinder pressure sensor according to the present invention.
FIG. 12 is an enlarged partial cross-sectional view of a main part showing a modification of the in-cylinder pressure sensor according to the present invention.
FIG. 13 is an enlarged fragmentary sectional view showing a main part of a modification of the in-cylinder pressure sensor according to the present invention.
FIG. 14 is an enlarged partial cross-sectional view of a main part showing a modification of the in-cylinder pressure sensor according to the present invention.
[Explanation of symbols]
1,1A, 1B In-cylinder pressure detection device
2, 2A, 30, 30A, 30B, 50, 50A In-cylinder pressure sensor
3 Power supply
5 Variable resistors
6 Crank angle sensor
7 Air flow meter
8 Cam angle sensor
9 D / A converter
10, 10A, 10B Control unit
20, 20a, 20b, 31, 53a, 53b Semiconductor device
23, 34, 52a, 52b Diaphragm
32, 32a, 32b Piezoelectric element
39 Spacer
58 Optical fiber sensor
CH Cylinder head
CR combustion chamber

Claims (10)

In the in-cylinder pressure detecting device for detecting the in-cylinder pressure of the engine,
An in-cylinder pressure sensor for detecting an in-cylinder pressure based on a change in resistance value according to the applied pressure;
A power source for supplying current to the in-cylinder pressure sensor;
An in-cylinder pressure detecting device comprising: a current value setting means for changing a value of a current supplied from the power source to the in-cylinder pressure sensor.   2. The in-cylinder pressure detecting device according to claim 1, wherein the current value setting unit sets a value of a current supplied from the power source to the in-cylinder pressure sensor based on a crank angle of the engine.   The current value setting means sets a value of a current supplied from the power source to the in-cylinder pressure sensor so that an output of the in-cylinder pressure sensor is amplified in an exhaust stroke and an intake stroke as compared with a compression stroke and an expansion stroke. The in-cylinder pressure detecting device according to claim 1, wherein the in-cylinder pressure detecting device is set.   The cylinder according to any one of claims 1 to 3, wherein the current value setting means can set a value of a current supplied from the power source to the in-cylinder pressure sensor in accordance with a load of the engine. Internal pressure detection device. In the in-cylinder pressure sensor used to detect the in-cylinder pressure of the engine,
Each having a plurality of in-cylinder pressure detecting means capable of detecting in-cylinder pressure, and the pressure detection ranges of the plurality of in-cylinder pressure detecting means are different from each other ;
The plurality of in-cylinder pressure detection means include detection means for mainly detecting in-cylinder pressure in the compression stroke and expansion stroke, and detection means for detecting in-cylinder pressure mainly in the exhaust stroke and intake stroke. and in-cylinder pressure sensor, characterized in that are. The in-cylinder pressure sensor according to claim 5 , wherein the plurality of in-cylinder pressure detecting means are integrated with each other. The in-cylinder pressure sensor according to claim 5 or 6 , wherein the plurality of in-cylinder pressure detecting means are arranged along a direction substantially orthogonal to each pressure receiving surface. The plurality of in-cylinder pressure detecting means includes a detecting means corresponding to a sensor pressure-receiving surface facing the cylinder and a detecting means corresponding to a sensor pressure-receiving surface that contacts a part of the engine. The in-cylinder pressure sensor according to claim 5 or 6 . The in-cylinder pressure sensor according to claim 5 or 6 , wherein a sensor pressure receiving surface corresponding to each of the plurality of in-cylinder pressure detecting means is included in a substantially same plane. At least one of the plurality of in-cylinder pressure detecting means is a piezoelectric element, and further includes a spacer that is arranged in contact with the piezoelectric element and concentrates stress on the piezoelectric element. The in-cylinder pressure sensor according to any one of claims 5 to 8 .

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