JP2006058127A - Cylinder pressure detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance productivity on a cylinder pressure detector by simplifying its structure. <P>SOLUTION: A diaphragm 13 is mounted on a front end part of a casing 11 to mount thereon a pressure transmission member 14 made of a conductive material so as to bring its front end part into contact with a rear face of the diaphragm 13. A detection element 15 is mounted on a rear end part of the transmission member 14 to mount thereon a second pressure transmission member 16 made of a conductive material so that the detection element 15 is sandwiched between the transmission members 16 and 14. A first electric wire 17 is put through the casing 11 and connected to the transmission member 14 while a second electric wire 18 is put through the casing 11 and connected to the transmission member 16. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an in-cylinder pressure detecting device that detects an in-cylinder pressure of an internal combustion engine.

  In an internal combustion engine control system, it is necessary to grasp the current combustion state of the internal combustion engine in order to execute ignition timing control, air-fuel ratio control, and knock control. There is a method for detecting the pressure of combustion gas in the chamber (cylinder) (hereinafter, in-cylinder pressure). An in-cylinder pressure sensor is known as a sensor for detecting the in-cylinder pressure. This in-cylinder pressure sensor generally applies pressure due to distortion of a resistor provided on the diaphragm, A sensing element in which the resistance value of the resistor changes according to the applied pressure is used.

  As a conventional in-cylinder pressure detection device, there is one described in Patent Document 1 below. This "combustion pressure sensor" described in Patent Document 1 has a diaphragm attached to the tip of a housing, a pressure transmission member provided in contact with the rear surface of the diaphragm in the housing, and a substrate so as to contact the pressure transmission member. The electrode pattern and the strain sensitive resistor are formed on this substrate.

JP-A-8-136384

  In the conventional combustion pressure sensor described above, in order to energize the electrode pattern, the tip of the lead wire is inserted into the through hole of the strain sensitive resistor and soldered to the electrode pattern on the front and back surfaces. Connected. However, since the combustion pressure sensor is mounted on the cylinder head so that the tip portion is exposed in the cylinder of the internal combustion engine, the combustion pressure sensor is extremely small, and the lead wire is connected to the electrode pattern located in the small casing. It is extremely difficult to connect the two by soldering. For this reason, the assembly work of the combustion pressure sensor becomes troublesome, the assembly time becomes long, and the assembly workability and productivity are lowered.

  The present invention is intended to solve such problems, and an object of the present invention is to provide an in-cylinder pressure detection device that is improved in productivity by simplifying the structure.

  In order to solve the above-described problems and achieve the object, an in-cylinder pressure detection device of the present invention is formed of a hollow casing, a diaphragm attached to a tip portion of the casing, and a conductive material. A pressure transmission member whose tip is in contact with the back surface of the diaphragm in the casing, a detection element mounted on a rear end of the pressure transmission member in the casing, and a tip passing through the casing An electrical wiring connected to the pressure transmission member is provided.

  Further, the in-cylinder pressure detecting device of the present invention includes a hollow casing, a diaphragm attached to the tip of the casing, and a conductive material, and the tip is located on the back surface of the diaphragm in the casing. A first pressure transmission member in contact; a detection element mounted on a rear end of the first pressure transmission member in the casing; and the first pressure transmission member formed in a conductive material and formed in the casing. And a second pressure transmission member for sandwiching the detection element, and an electrical wiring having a tip connected to the first pressure transmission member through the casing.

  In the in-cylinder pressure detection device of the present invention, the natural frequency of the pressure transmission member or the first pressure transmission member is set to a resonance frequency of secondary knocking in the internal combustion engine.

  In the in-cylinder pressure detecting device of the present invention, a connecting ring is connected to a tip portion of the electric wiring, and the pressure transmitting member or the first pressure transmitting member is fitted to the connecting ring.

  According to the in-cylinder pressure detecting device of the present invention, a diaphragm is attached to the tip of a hollow casing, and the tip of the pressure transmission member formed of a conductive material is in contact with the back surface of the diaphragm in the casing. Since the detection element is attached to the rear end portion of the pressure transmission member and the electric wiring is connected to the pressure transmission member through the casing, the pressure transmission member is made of a conductive material, By simply connecting the electrical wiring, it can be electrically connected to the sensing element in contact with this pressure transmission member, eliminating the need for direct wiring to the sensing element, simplifying the structure, and producing Can be improved.

  Further, according to the in-cylinder pressure detecting device of the present invention, the diaphragm is attached to the tip of the hollow casing, and the tip of the first pressure transmission member formed of the conductive material is formed in the casing. It is mounted so as to be in contact with the back surface, a detection element is mounted on the rear end portion of the first pressure transmission member, and the detection element is sandwiched between the second pressure transmission member formed of a conductive material and the first pressure transmission member. Since the electrical wiring is connected to the first pressure transmission member through the casing, only the electrical wiring is connected to the first pressure transmission member by configuring the first and second pressure transmission members with a conductive material. Thus, the detection element and the second pressure transmission member in contact with the first pressure transmission member can be electrically connected, and no direct wiring to the detection element is required, and the structure can be simplified. ,productivity It can be improved.

  Embodiments of an in-cylinder pressure detecting device according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

  FIG. 1 is a cross-sectional view illustrating an in-cylinder pressure detecting device according to an embodiment of the present invention, and FIG. 2-1 is a connection procedure between a first pressure transmission member and electric wiring in the in-cylinder pressure detecting device of the present embodiment. FIG. 2-2 is a perspective view illustrating a connection state between the first pressure transmission member and the electrical wiring in the in-cylinder pressure detection device of the present embodiment.

  Although not shown, the in-cylinder pressure detecting device of the present embodiment is installed in the combustion chamber of the internal combustion engine and constantly detects the pressure of the combustion gas in the combustion chamber (cylinder), that is, the in-cylinder pressure. The detected in-cylinder pressure is used for ignition timing control, air-fuel ratio control, knocking control, and the like. The in-cylinder pressure detecting device is configured to detect the in-cylinder pressure using a detection element whose resistance value changes according to the applied pressure, that is, the in-cylinder pressure.

  In the in-cylinder pressure detecting apparatus of the present embodiment, as shown in FIG. 1 and FIG. 1, the casing 11 is made of metal or synthetic resin and has a hollow cylindrical shape, the base end portion is a support portion 12, and an insulator is provided at the tip end portion. A diaphragm 13 is attached. The casing 11 is located between the support portion 12 and the diaphragm 13 and includes a first pressure transmission member 14, a detection element 15, and a second pressure transmission member 16 that are stacked. .

  The first pressure transmission member 14 has a predetermined length and a cylindrical shape having an outer diameter smaller than the inner diameter of the casing 11 and is formed of a conductive material such as stainless steel or aluminum. And in the casing 11, the 1st pressure transmission member 14 is arrange | positioned so that a front-end | tip part may contact the back surface of the diaphragm 13. As shown in FIG. The detection element 15 is configured by a piezoelectric element, a resistance element, or the like, and is disposed in the casing 11 so as to contact the rear end portion of the first pressure transmission member 14.

  The second pressure transmission member 16 has a cylindrical shape having an outer diameter thinner than the inner diameter of the casing 11, and is formed of a conductive material such as stainless steel or aluminum. In the casing 11, the second pressure transmission member 16 is disposed such that the front end portion contacts the rear end portion of the detection element 15 and the rear end portion contacts the support portion 12. That is, the first pressure transmission member 14, the detection element 15, and the second pressure transmission member 16 have substantially the same outer diameter, and the detection element 15 is detected by the first pressure transmission member 14 and the second pressure transmission member 16 in the casing 11. Is held at a predetermined pressure.

  The end portion of the first electric wiring 17 is inserted into the casing 11 through the through hole 12 a of the support portion 12 and connected to the outer peripheral portion of the first pressure transmission member 14. Further, the end portion of the second electric wiring 18 is inserted into the casing 11 through the through hole 12 b of the support portion 12 and is connected to the end portion of the second pressure transmission member 16.

  In this case, as shown in FIG. 2A, the first pressure transmission member 14 is formed to have an inverted truncated cone shape with the lower portion formed slightly narrow, and a ring is formed at the tip of the first electric wiring 17. The connecting ring 19 having a shape is connected, and the inner diameter of the connecting ring 19 is set to be an outer diameter at a substantially intermediate position in the longitudinal direction of the first pressure transmission member 14. Then, as shown in FIG. 2B, the first pressure transmission member 14 is inserted into the connection ring 19 from above, so that the connection ring 19 is fitted to the intermediate position of the first pressure transmission member 14. Then, the first electric wiring 17 is electrically connected to the first pressure transmission member 14. Note that fastening means such as adhesion and soldering may be used as necessary.

  Further, in the present embodiment, the natural frequency of the first pressure transmission member 14, the detection element 15, and the second pressure transmission member 16 that are configured substantially integrally is set to be the primary knocking resonance frequency in the internal combustion engine. Has been. Further, the first pressure transmission member 14 is set so that its natural frequency becomes a secondary knocking resonance frequency in the internal combustion engine.

In this case, the natural frequency f of the substance is set by the following formula using the mass m and the spring constant K.
f = 1 / 2π · √K / m

  As shown in FIG. 1, the in-cylinder pressure detecting apparatus of the present embodiment configured as described above is mounted on the cylinder head 21 of the internal combustion engine so that the tip portion faces the combustion chamber 22.

  Accordingly, when the pressure in the combustion chamber 22 fluctuates, the pressure fluctuation is transmitted from the diaphragm 13 to the detection element 15 via the first pressure transmission member 14. That is, the detection element 15 receives the pressure fluctuation in the combustion chamber 22 as the fluctuation of the compressive force between the first pressure transmission member 14 and the second pressure transmission member 16, and the change amount of the resistance value due to this fluctuation is the electric wiring 17, 18. The in-cylinder pressure can be properly detected.

  At this time, the natural frequency of the first pressure transmission member 14, the detection element 15, and the second pressure transmission member 16 is set to be the primary knocking resonance frequency, and the natural frequency of the first pressure transmission member 14 is It is set to have a secondary knocking resonance frequency, and the output resistance value is amplified. Therefore, the primary knocking and the secondary knocking of the internal combustion engine can be detected with high accuracy, and by appropriately detecting the secondary knocking, the in-cylinder pressure fluctuation due to the piston stroke fluctuation is eliminated, and the internal combustion engine knocking is eliminated. Can be reliably detected.

  As described above, in the in-cylinder pressure detecting device of the present embodiment, the diaphragm 13 is attached to the tip of the casing 11, and the tip of the first pressure transmission member 14 made of a conductive material is in contact with the back surface of the diaphragm 13. The detection element 15 is attached to the rear end portion of the first pressure transmission member 14 so that the second pressure transmission member 16 made of a conductive material is sandwiched between the first pressure transmission member 14 and the detection element 15. The first electric wiring 17 is connected to the first pressure transmission member 14 through the casing 11, while the second electric wiring 18 is connected to the second pressure transmission member 16 through the casing 11.

  Accordingly, the first and second pressure transmission members 14 and 16 are made of a conductive material, so that the electric transmission wires 14 and 16 are connected to the pressure transmission members 14 and 16 and the pressure transmission members 14 and 16 are brought into contact with each other. It can be electrically connected to the detection element 15 in the state, and direct wiring to the detection element 15 is not required, the structure of the entire apparatus can be simplified, and productivity can be improved.

  In the present embodiment, the connection of the first electric wiring 17 to the first pressure transmission member 14 is performed using the connection ring 19. Therefore, the electrical connection between the first electrical wiring 17 and the first pressure transmission member 14 can be easily performed, the work in the narrow casing 11 can be performed, and the assembly work of the apparatus can be easily performed in a short time. be able to.

  Furthermore, the natural frequency of the first pressure transmission member 14, the detection element 15, and the second pressure transmission member 16 is set to be the primary knocking resonance frequency, and the natural frequency of the first pressure transmission member 14 is the secondary knocking resonance. The frequency is set. Therefore, the output value at the time of primary knocking and secondary knocking is amplified, and primary knocking and secondary knocking of the internal combustion engine can be detected with high accuracy, and secondary knocking can be detected appropriately. Thus, knocking of the internal combustion engine can be reliably detected by eliminating in-cylinder pressure fluctuation due to piston stroke fluctuation. As a result, a separate sensor for detecting knocking is not required and the cost can be reduced.

  In the above-described embodiment, the first pressure transmission member 14, the detection element 15, and the second pressure transmission member 16 are stacked in the casing 11 so as to come into contact with the diaphragm 13. 13, the first pressure transmission member 14 and the detection element 15 are provided in a laminated state so that the natural frequency of the first pressure transmission member 14 and the detection element 15 is set to be the primary knocking resonance frequency. The natural frequency of the first pressure transmission member 14 may be set to be the secondary knocking resonance frequency.

  Further, in the connection between the first pressure transmission member 14 and the first electrical wiring 17, the first pressure transmission member 14 is formed in a truncated cone shape, and the coupling ring 19 fitted to the first pressure transmission member 14 is used. However, the present invention is not limited to this. For example, a step portion may be provided on the first pressure transmission member 14 so that the connection ring 19 is engaged with the step, and a hook that is engaged with the first pressure transmission member 14 is used instead of the connection ring 19. Also good.

  As described above, the in-cylinder pressure detecting device according to the present invention is effective for improving productivity by effectively wiring the detecting element, and is useful as an in-cylinder pressure detecting device for all internal combustion engines. It is.

It is sectional drawing showing the cylinder pressure detection apparatus which concerns on one Example of this invention. It is a perspective view showing the connection procedure of the 1st pressure transmission member and electric wiring in the cylinder pressure detection apparatus of a present Example. It is a perspective view showing the connection state of the 1st pressure transmission member and electric wiring in the cylinder pressure detection apparatus of a present Example.

Explanation of symbols

11 Casing 13 Diaphragm 14 First pressure transmission member (pressure transmission member)
15 detection element 16 second pressure transmission member (pressure transmission member)
17 1st electrical wiring 18 2nd electrical wiring 19 Connecting ring 21 Cylinder head 22 Combustion chamber

Claims (4)

  A hollow casing, a diaphragm attached to the tip of the casing, a pressure transmission member formed of a conductive material and having a tip contacting the back surface of the diaphragm in the casing, and in the casing An in-cylinder pressure detection device comprising: a detection element mounted on a rear end portion of the pressure transmission member; and an electrical wiring having a front end portion connected to the pressure transmission member through the casing.   A casing having a hollow shape, a diaphragm attached to a front end portion of the casing, a first pressure transmission member formed of a conductive material and having a front end portion contacting the back surface of the diaphragm in the casing, and the inside of the casing A second pressure transmission member formed by a conductive material and sandwiching the detection element between the first pressure transmission member and the first pressure transmission member in the casing. And an in-cylinder pressure detecting device including an electrical wiring having a tip portion connected to the first pressure transmission member through the casing.   3. The cylinder pressure detection device according to claim 1, wherein a natural frequency of the pressure transmission member or the first pressure transmission member is set to a resonance frequency of secondary knocking in an internal combustion engine. Internal pressure detection device.   3. The in-cylinder pressure detecting device according to claim 1, wherein a connecting ring is connected to a distal end portion of the electric wiring, and the pressure transmitting member or the first pressure transmitting member is fitted to the connecting ring. In-cylinder pressure detection device.

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