JP2008070212A - Cylindrical internal pressure sensor mounting structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cylindrical internal pressure sensor mounting structure capable of miniaturizing a cylindrical internal pressure sensor, and securing desired output accuracy by improving heat releasability. <P>SOLUTION: Concerning a cylinder head 33 wherein a cylindrical internal pressure sensor mounting hole 35 whose one end is opened to a combustion chamber is formed, a flame response reduction cover 70 having an air hole 70C is provided on the cylinder head 33, in the arranged state in front of the furthermore combustion chamber opening side of the cylindrical internal pressure sensor mounting hole than the position of a pressure receiving part 6A of the cylindrical internal pressure sensor 6 in the mounting state of the cylindrical internal pressure sensor 6. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an in-cylinder pressure sensor mounting structure for an engine including an in-cylinder pressure sensor that detects a pressure in the cylinder.

  In recent years, engine control devices have been developed that directly detect in-cylinder information such as pressure and temperature in a cylinder and control the ignition timing, fuel injection amount, and the like to optimum values based on the in-cylinder information. Has reached. As a sensor that detects in-cylinder information, an in-cylinder pressure sensor that detects pressure in the cylinder (in-cylinder pressure) is used.

  As such an in-cylinder pressure sensor, a pressure receiving portion comprising a metal housing fixed to the combustion chamber wall and having a tip facing the combustion chamber, and comprising a diaphragm or the like positioned at the inner end of the pressure introduction path opened at the tip And a semiconductor in-cylinder pressure sensor (for example, Patent Document 1) mainly composed of, for example, a strain gauge or an element portion made of a semiconductor that generates an output in accordance with the pressure applied to the pressure receiving portion. There is known an optical in-cylinder pressure sensor (for example, Patent Document 2) that detects pressure based on the intensity of light reflected from a responding sensor diaphragm.

  By the way, in such an in-cylinder pressure sensor, it is known that it becomes difficult to ensure desired output accuracy due to the influence of thermal shock caused by a high-temperature combustion gas flame. That is, in the semiconductor cylinder pressure sensor, the output characteristics of the semiconductor differ due to temperature, and in the optical cylinder pressure sensor, the material deformation or stress of the sensor diaphragm due to thermal shock is erroneously detected as pressure. It will be done.

  Therefore, in order to mitigate the influence of the thermal shock caused by this flame, Patent Document 1 discloses that the flame extinguishing is made of a highly heat-conductive material having a large number of air holes in the middle of the pressure introduction path formed in the metal housing. A pressure detector is disclosed which is provided with a body to prevent a flame entering the pressure introduction path. Further, Patent Document 2 discloses a pressure sensor housed in a casing, which is made of a heat conductive material and has an opening provided with an opening in front of a sensor diaphragm. Heat is transmitted through the heat insulating material. A pressure sensor adapted to be led to a casing is disclosed.

Japanese Patent Laid-Open No. 63-3233 Japanese Patent Application Laid-Open No. 2004-286753

  By the way, due to the adoption of multi-valve mechanisms and in-cylinder injection valves that meet the demand for higher engine performance in recent years, in-cylinder pressure sensors have limited space for mounting on their cylinder heads, and their downsizing In particular, there is a strong demand for reducing the diameter.

  However, any of the in-cylinder pressure sensors disclosed in Patent Documents 1 and 2 is held in a metal housing or casing that constitutes a part of the in-cylinder pressure sensor, and the flame extinguisher and the heat insulating material are integrated with the sensor body. Is provided in front of the diaphragm, which is the pressure receiving body, and the sensor diaphragm, and therefore, there is a problem that it is unavoidable that the entire sensor is enlarged. Furthermore, since the heat accumulated in the flame extinguishing body and the heat insulating material is led out through the metal housing and casing, the heat radiation cannot be said to be sufficient, and the temperature of the in-cylinder pressure sensor becomes high and the desired output accuracy can be ensured. It also has the problem of being difficult.

  Accordingly, an object of the present invention is to eliminate such a conventional problem, enable downsizing of the in-cylinder pressure sensor, improve heat dissipation, and ensure desired output accuracy. To provide a mounting structure.

In order to achieve the above object, an in-cylinder pressure sensor mounting structure according to an embodiment of the present invention is provided in a cylinder head in which an in-cylinder pressure sensor mounting hole whose one end opens into a combustion chamber is formed.
A flame response reducing member having a vent hole is provided in front of the combustion chamber opening side of the in-cylinder pressure sensor mounting hole rather than the pressure receiving portion position of the in-cylinder pressure sensor in the attached state of the in-cylinder pressure sensor, and is provided in the cylinder head. It is characterized by being.

  According to this aspect of the present invention, the flame response reducing member having the air vent is disposed in front of the combustion chamber opening side of the cylinder pressure sensor mounting hole with respect to the pressure receiving portion position of the cylinder pressure sensor when the cylinder pressure sensor is attached. And provided in the cylinder head. Therefore, the flame generated in the combustion chamber is blocked by the flame response reducing member placed in front of the combustion chamber opening, and does not reach the pressure receiving portion of the in-cylinder pressure sensor, thereby mitigating the influence of the thermal shock caused by the flame on the in-cylinder pressure sensor. Is done. On the other hand, since the pressure reaches the pressure receiving portion of the in-cylinder pressure sensor through the ventilation hole of the flame response reducing member, the in-cylinder pressure sensor itself only needs to have a structure sufficient to obtain the sensor function, and its downsizing, In particular, the diameter can be reduced, and the mountability of the sensor can be improved. Furthermore, since the heat applied to the flame response reducing member is dissipated to the cylinder head, there is little thermal influence on the in-cylinder pressure sensor, and the desired output accuracy of the in-cylinder pressure sensor is ensured.

  Here, the vent hole of the flame response reducing member may have a spiral shape.

  According to this form, the direct impact of the flame to the pressure receiving part of the in-cylinder pressure sensor is prevented, and the intrusion of the deposit into the surrounding space is prevented, so that accumulation can be effectively prevented.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a system configuration diagram of an engine 1 having an in-cylinder pressure sensor mounting structure according to the present embodiment.

  The illustrated engine (internal combustion engine) 1 is a so-called direct injection type spark ignition engine for a vehicle, and is preferably a multi-cylinder engine (only one cylinder is shown). For each cylinder, an injector 11 as a fuel injection valve that injects fuel directly into the cylinder 31 is provided. The fuel used for the engine 1 is gasoline in the present embodiment, but may be alcohol or a mixed fuel of this with gasoline, a gaseous fuel such as CNG, and other alternative fuels.

  Air sucked from an air cleaner (not shown) is distributed and supplied to the in-cylinder combustion chamber of each cylinder via the intake passage 5. The intake passage 5 is defined by an intake pipe 51, an intake manifold 52, and an intake port 41 that are sequentially arranged from the upstream side. The intake manifold 52 includes a surge tank 4 as a collecting portion located on the upstream side, and a branch pipe 53 for each cylinder in which one end is connected to the surge tank 4 and the other end is connected to the intake port 41 of each cylinder. Become. The intake pipe 51 is provided with an air flow meter 2 and an electronically controlled throttle valve 3.

  The injector 11 is controlled by an electronic control unit (hereinafter referred to as ECU) 100 as control means so as to perform fuel injection in one or both of an intake stroke and a compression stroke. In the case of compression stroke injection, fuel is injected into the concave portion 44 at the top of the rising piston 43, and fuel and air are mixed in the process of generating a tumble-like flow that winds up along the inner surface of the concave portion 44, A relatively rich mixture layer is formed in the vicinity of the spark plug 7 and a relatively lean mixture layer is formed therearound. The injector 11 is opened by an ON signal output from the ECU 100, injects fuel, is closed by an OFF signal output from the ECU 100, and stops fuel injection.

  Exhaust gas from the engine 1 is exhausted through an exhaust passage 8. The exhaust passage 8 includes an exhaust port 45 formed for each cylinder in the cylinder head of the engine 1, an exhaust manifold 54 connected to the exhaust port 45, and an exhaust purification catalyst connected downstream of the exhaust manifold 54. 9 and an exhaust pipe 55 connected to the downstream side of the catalyst 9. The exhaust manifold 54 is composed of a branch pipe for each cylinder connected to the exhaust port 45 of each cylinder, and a collecting portion located on the downstream side of the branch pipe.

  The intake port 41 and the exhaust port 45 are opened and closed by an intake valve 42 and an exhaust valve 46, respectively. The intake valve 42 and the exhaust valve 46 are opened and closed by the intake valve camshaft 12 and the exhaust valve camshaft 13, respectively. A variable valve timing mechanism for making the opening / closing timing of the intake valve 42 and the exhaust valve 46 variable may be provided.

  The ECU 100 includes a microcomputer including a CPU, a ROM, a RAM, an A / D converter, an input / output interface, and the like, performs predetermined arithmetic processing based on output signals from various sensors, The spark plug 7 and the drive motor 19 of the throttle valve 3 are controlled to control the fuel injection amount, fuel injection timing, ignition timing, intake air amount, and the like.

  The sensors include the air flow meter 2 described above. The air flow meter 2 outputs a signal corresponding to the flow rate of the intake air passing therethrough to the ECU 100. ECU 100 calculates the engine load factor based on the output value of air flow meter 2. The sensors include a crank sensor 24 that detects the angle of the crankshaft 23. The crank sensor 24 outputs a pulse signal at predetermined crank angle intervals. Based on this pulse signal, ECU 100 detects the actual crank angle of engine 1 and calculates the rotational speed.

  Further, an accelerator opening sensor 27 that detects the amount of depression of the accelerator pedal (accelerator opening), a throttle position sensor 28 that detects the opening of the throttle valve 3, and a cooling water temperature (hereinafter simply referred to as a water temperature) of the engine 1 are detected. The sensors include a water temperature sensor 29 and an air-fuel ratio sensor 30 that detects the oxygen concentration of the exhaust gas.

  The opening degree of the throttle valve 3 is controlled by the ECU 100. That is, the ECU 100 normally controls the drive motor 19 so that the output value of the throttle position sensor 28 becomes a value corresponding to the output value of the accelerator opening sensor 27.

  An in-cylinder pressure sensor 6 for detecting in-cylinder information, in particular, the pressure in the combustion chamber (in-cylinder pressure) in the cylinder 31 is provided. The in-cylinder pressure sensor 6 outputs a voltage signal corresponding to the in-cylinder pressure to the ECU 100. The ECU 100 calculates the in-cylinder pressure based on the signal obtained from the in-cylinder pressure sensor 6. The in-cylinder pressure sensor 6 is disposed on the cylinder head 33 with the pressure receiving portion provided at the tip thereof facing the inside of the cylinder 31.

  The in-cylinder pressure sensor 6 in the present embodiment is configured as shown in FIG. 2, for example. The in-cylinder pressure sensor 6 includes a small-diameter portion 6B having a pressure-receiving portion 6A that faces the inside of the cylinder, a large-diameter portion 6C positioned on the proximal end side, and a step positioned between the small-diameter portion 6B and the large-diameter portion 6C. Part or shoulder part 6D. The shoulder portion 6D in the present embodiment is formed by a conical surface having a tapered annular shape. The in-cylinder pressure sensor 6 includes an element portion 61 that outputs a signal corresponding to the force applied to itself, and a transmission member 62 that transmits the pressure applied to the pressure receiving portion 6A to the element portion. Yes. The pressure receiving portion 6A is made of a metal diaphragm and can be deformed in the sensor axial direction according to the applied pressure. The element unit 61 includes, for example, a silicon-based semiconductor element, and changes an electric resistance value according to a force applied to itself. A current from the ECU 100 is passed through the element unit 61. The transmission member 62 is interposed between the pressure receiving part 6A and the element part 61, transmits the force applied to the pressure receiving part 6A to the element part 61, and prevents the heat of the pressure receiving part 6A from being transmitted to the element part 61. It also has a heat insulation function.

  In the in-cylinder pressure sensor 6, when the pressure in the cylinder is applied to the pressure receiving portion 6 </ b> A, the pressure receiving portion 6 </ b> A bends to cause the transmission member 62 to receive a compressive force, and this compressive force is transmitted to the element portion 61. As a result, the element unit 61 is also compressed, and its electric resistance value is changed. Eventually, the element unit 61 outputs a voltage signal that changes in accordance with the in-cylinder pressure to the ECU 100. The ECU 100 detects the in-cylinder pressure based on this output signal.

  Various in-cylinder pressure sensors other than those described here can be used. For example, the above-described optical in-cylinder pressure sensor including an optical fiber or the like can also be used.

  On the other hand, the cylinder pressure sensor mounting hole 35 formed in the cylinder head 33 has one end opened to the combustion chamber and a small diameter hole portion 35A surrounding the small diameter portion 6B of the cylinder pressure sensor 6 in a non-contact state, and a cylinder A large-diameter hole portion 35B that accommodates the large-diameter portion 6C of the internal pressure sensor 6, and a step portion 35C that is located between the small-diameter hole portion 35A and the large-diameter hole portion 35B and that contacts the shoulder portion 6D of the in-cylinder pressure sensor 6 And have. The step portion 35 </ b> C according to the present embodiment is formed by a tapered conical surface corresponding to the shoulder portion 6 </ b> D of the in-cylinder pressure sensor 6. In the in-cylinder pressure sensor mounting hole 35 according to the present embodiment, a female screw 35D for mounting a flame response reducing member to be described later is formed on the inner surface of the opening end.

  The in-cylinder pressure sensor mounting hole 35 is a stepped hole having a step portion 35C, and the shoulder portion 6D of the in-cylinder pressure sensor 6 is sealed by being in contact with the step portion 35C. Yes.

  Here, the flame response reducing member will be described. In the first embodiment, the flame response reducing cover 70 is formed as a flame response reducing cover 70. As shown in detail in FIGS. 3 (A) and 3 (B), the flame response reducing cover 70 includes a disc-shaped portion 70A and a cylindrical portion 70B erected on the back surface of the disc-shaped portion 70A. It is mainly composed. The disk-like portion 70A is formed with a plurality of vent holes 70C (in this embodiment, four elongated holes in a cross shape) in a form that allows communication between the front surface and the inside of the cylindrical portion 70B on the back surface. In addition, a male screw 70D is formed on the outer periphery of the tubular portion 70B. The male screw 70D is screwed with the female screw 35D. The flame response reducing cover 70 is preferably made of a highly heat conductive material such as SUS430 or aluminum and is made of the same material as the cylinder head 33 so as to have the same thermal expansion coefficient. The size of the vent hole 70C may be set to a size that can prevent the passage of the flame without hindering the propagation of pressure, and the shape thereof is arbitrary.

  As shown in FIG. 2, the flame response reduction cover 70 formed in this way has the cylindrical portion 70 </ b> B with the washer 72 interposed between the back surface of the disc-shaped portion 70 </ b> A and the cylinder head 33. The male screw 70 </ b> D is screwed into the female screw 35 </ b> D on the inner surface of the open end of the in-cylinder pressure sensor mounting hole 35 and is mounted on the cylinder head 33. As a result, the flame response reduction cover 70 is placed in front of the combustion chamber opening side of the in-cylinder pressure sensor mounting hole 35 with respect to the position of the pressure receiving portion 6A of the in-cylinder pressure sensor 6 in the mounted or mounted state of the in-cylinder pressure sensor 6. Then, a predetermined space 74 is interposed between the back surface of the disk-shaped portion 70 </ b> A of the flame response reducing cover 70 and the pressure receiving portion 6 </ b> A of the in-cylinder pressure sensor 6, and is provided in the cylinder head 33.

  Thus, according to the first embodiment, the flame generated in the combustion chamber is blocked by the flame response reducing cover 70 placed in front of the combustion chamber opening side, and does not reach the pressure receiving portion 6A of the in-cylinder pressure sensor 6. The influence of the thermal shock due to the flame on the in-cylinder pressure sensor 6 is mitigated. On the other hand, since the pressure reaches the pressure receiving portion 6A of the in-cylinder pressure sensor 6 through the vent hole 70C of the flame response reducing cover 70, the in-cylinder pressure sensor 6 itself can accurately detect the pressure. Further, a predetermined space 74 is secured between the flame response reduction cover 70 and the pressure receiving portion 6A of the in-cylinder pressure sensor 6, and heat applied to the flame response reduction cover 70 is directly radiated to the cylinder head 33. Therefore, the thermal influence on the in-cylinder pressure sensor 6 is small, and the desired output accuracy of the in-cylinder pressure sensor 6 is ensured.

  Next, a second embodiment of the flame response reducing member will be described with reference to FIG. In the first embodiment, a flame response reduction cover 70 as a flame response reduction member is provided in the combustion chamber opening of the in-cylinder pressure sensor mounting hole 35, and the vent hole 70C is mounted in the in-cylinder pressure sensor 6 or in-cylinder pressure sensor. Whereas the flame response reducing member in the second embodiment is a spiral plate 80, the only difference is that the vent hole has a spiral shape. Therefore, the same reference numerals are used for the same functional parts as in the first embodiment, and a duplicate description is avoided.

  As shown in FIG. 4, the spiral plate 80 is placed in front of the combustion chamber opening side of the in-cylinder pressure sensor mounting hole 35 with respect to the position of the pressure receiving portion 6A of the in-cylinder pressure sensor 6, and the outer peripheral portion of the spiral blade 80A is the in-cylinder pressure sensor. The cylinder head 33 is mounted by being fixed to an annular groove 35E formed in the mounting hole 35. A spiral vent 80B is formed in a region where the spiral blades 80A overlap each other. The vent hole 80B opens in a spiral direction with respect to the axial direction of the in-cylinder pressure sensor mounting hole 35.

  According to the second embodiment, the flame generated in the combustion chamber is blocked by the spiral plate 80, and the flame directly reaches the pressure receiving portion 6A of the in-cylinder pressure sensor 6 by the vent hole 80B opened in the spiral direction. Therefore, the influence of the thermal shock caused by the flame on the in-cylinder pressure sensor 6 is mitigated. On the other hand, since the pressure reaches the pressure receiving portion 6A of the in-cylinder pressure sensor 6 through the vent hole 80B of the spiral plate 80, the in-cylinder pressure sensor 6 itself can detect the pressure with high accuracy. Similarly to the previous embodiment, a predetermined space 74 is secured between the spiral plate 80 and the pressure receiving portion 6A of the in-cylinder pressure sensor 6, and heat applied to the spiral plate 80 is directly applied to the cylinder head 33. Therefore, a desired output accuracy of the in-cylinder pressure sensor 6 is ensured.

  Furthermore, a third embodiment of the flame response reducing member will be described with reference to FIG. In the first or second embodiment, the flame response reduction cover 70 or the spiral plate 80 as the flame response reduction member is provided on the combustion chamber opening side of the in-cylinder pressure sensor mounting hole 35, whereas The flame response reducing member in the third embodiment is a spiral coil 90, and the only difference is that the vent hole has a spiral shape. Therefore, the same reference numerals are used for the same functional parts as in the first or second embodiment, and a duplicate description is avoided.

  As shown in FIG. 5, the spiral coil 90 is placed in front of the combustion chamber opening side of the in-cylinder pressure sensor mounting hole 35 with respect to the position of the pressure receiving portion 6 </ b> A of the in-cylinder pressure sensor 6. The outer peripheral portion of the wire with the maximum diameter is fixed to an annular groove 35E formed in the cylinder pressure sensor mounting hole 35, and the cylinder head 33 is mounted. A spiral air hole 90B is formed in a region where the filaments 90A forming the spiral coil 90 are adjacent to each other. The ventilation hole 90 </ b> B opens in a spiral direction with respect to the axial direction of the in-cylinder pressure sensor mounting hole 35.

  According to the third embodiment, the flame generated in the combustion chamber is interrupted by the spiral coil 90, and the flame directly reaches the pressure receiving portion 6A of the in-cylinder pressure sensor 6 by the vent hole 90B opened in the spiral direction. Therefore, the influence of the thermal shock caused by the flame on the in-cylinder pressure sensor 6 is mitigated. On the other hand, since the pressure reaches the pressure receiving portion 6A of the in-cylinder pressure sensor 6 via the vent hole 90B of the spiral coil 90, the in-cylinder pressure sensor 6 itself can detect the pressure with high accuracy. As in the previous embodiment, a predetermined space 74 is secured between the spiral coil 90 and the pressure receiving portion 6A of the in-cylinder pressure sensor 6, and heat applied to the spiral coil 90 is directly applied to the cylinder head 33. Therefore, a desired output accuracy of the in-cylinder pressure sensor 6 is ensured.

  According to the in-cylinder pressure sensor mounting structure according to the first to third embodiments described above, the flame response reducing member prevents the direct hit of the flame to the pressure receiving portion 6A of the in-cylinder pressure sensor 6 and the surroundings thereof. Since deposits are prevented from entering the space, deposit accumulation is effectively prevented. Therefore, this in-cylinder pressure sensor mounting structure is preferably used in combination with the aforementioned shoulder seal type in-cylinder pressure sensor 6. That is, in the case of the in-cylinder pressure sensor 6 of the shoulder seal type, a deposit enters between the small-diameter portion 6B of the in-cylinder pressure sensor 6 and the small-diameter hole portion 35A of the in-cylinder pressure sensor mounting hole 35 surrounding it in a non-contact state. As a result of the deposition, the heat dissipation on the tip side of the shoulder portion 6D is changed, and there is a problem that the detection accuracy is lowered due to the temperature characteristics. However, such intrusion and deposition of deposits are prevented in advance.

  It should be noted that the present invention is not limited to the above-described embodiment, and includes all modifications, applications, and equivalents included in the concept of the present invention defined by the claims. For example, although the above-described flame response reducing member has been described as being retrofitted, it is needless to say that this may be provided in the cylinder head by casting.

1 is a system configuration diagram of an engine having an in-cylinder pressure sensor mounting structure according to an embodiment of the present invention. It is sectional drawing which shows the cylinder pressure sensor attachment structure which concerns on one Embodiment of this invention with a cylinder pressure sensor. It is the (A) half section side view and (B) top view showing the 1st embodiment of the flame response reducing member concerning the present invention. It is sectional drawing which shows the cylinder pressure sensor attachment structure which concerns on other embodiment of this invention with a cylinder pressure sensor. It is sectional drawing which shows the cylinder pressure sensor attachment structure which concerns on further another embodiment of this invention with a cylinder pressure sensor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine 6 In-cylinder pressure sensor 6A Pressure receiving part 6B Small diameter part 6C Large diameter part 6D Shoulder part (step part)
33 Cylinder Head 35 Cylinder Pressure Sensor Mounting Hole 35A Small Diameter Hole 35B Large Diameter Hole 35C Step 35D Female Thread 35E Annular Groove 70 Flame Response Reduction Cover (Flame Response Reduction Member)
70A Disc-shaped part 70B Cylindrical part 70C Vent hole 70D Male thread 80 Spiral plate (flame response reducing member)
80A Spiral Wing 80B Ventilation Hole 90 Spiral Coil (Flame Response Reduction Member)
90A Wire 90B Vent

Claims (2)

In the cylinder head in which the cylinder pressure sensor mounting hole whose one end opens into the combustion chamber is formed,
A flame response reducing member having a vent hole is provided in front of the combustion chamber opening side of the in-cylinder pressure sensor mounting hole rather than the pressure receiving portion position of the in-cylinder pressure sensor in the attached state of the in-cylinder pressure sensor, and is provided in the cylinder head. An in-cylinder pressure sensor mounting structure characterized by being provided.   The in-cylinder pressure sensor mounting structure according to claim 1, wherein the vent hole of the flame response reducing member has a spiral shape.

Images