Insulator and fitting structure for reducing vibration propagation of injector

Abstract

To provide an insulator that can reduce propagation of vibration to an engine which is generated when an injector is seated.SOLUTION: An insulator 30 includes a bottomless cylindrical body part 30a having a predetermined radial thickness. The body part 30a has a hollow interior which is kept in a vacuum state. The body part 30a has an inner diameter and an inner peripheral surface which can be externally fitted to a tip part outer periphery of an injector 12. The inner diameter and the inner peripheral surface of the body part 30a are configured to be capable of being inserted into an injector fitting hole 10a of an engine 10.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to an insulator and an injector mounting structure that uses the insulator to reduce vibration transmission. [Background technology]

[0002] Injectors have been widely used in engines for injecting fuel (as fuel injection devices). An injector is primarily composed of a plunger, a solenoid coil, a return spring, and the like. When the solenoid coil of the injector is energized, the plunger is attracted and moves away from the valve seat (opening the valve), and fuel is injected. On the other hand, when the solenoid coil is de-energized, the force of the return spring returns the plunger, which then seats on the valve seat and closes the valve (i.e., fuel injection is stopped).

[0003] It is known that vibration occurs when the plunger of an injector seats on the valve seat during valve closing. The vibration caused by the injector seating can be picked up by the knock sensor (falsely detecting it as knocking), leading to an erroneous retardation of the ignition timing. In recent years, the shift to direct injection (direct-cylinder injection) in engines has led to increased fuel pressure, which has led to a tendency for vibration during seating to become even greater.

[0004] Therefore, for example, Patent Document 1 discloses a technique in which, under operating conditions in which the knock determination period overlaps with the fuel injection period of an injector, the knock determination period is shortened from the default setting to prevent the knock determination period from overlapping with the fuel injection period. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-251218 Summary of the Invention [Problem to be solved by the invention]

[0006] However, with the above-described techniques, there may be cases (operating conditions) where the knock determination period or the fuel injection period cannot be optimally set, which may result in limitations (restrictions) on engine performance.

[0007] The present invention has been made to solve the above problems, and aims to provide an insulator that can reduce the transmission of vibrations generated when the injector is seated to the engine, and an injector mounting structure that uses the insulator to reduce the transmission of vibrations. [Means for solving the problem]

[0008] An insulator according to one aspect of the present invention comprises a bottomless cylindrical main body portion having a predetermined radial thickness, the interior of the main body portion being hollow and maintained in a vacuum state, the inner diameter and inner peripheral surface of the main body portion being formed so as to be able to fit onto the outer periphery of the tip end of an injector, and the outer diameter and outer peripheral surface of the main body portion being formed so as to be able to be inserted into an injector mounting hole of an engine.

[0009] According to one aspect of the present invention, an insulator has a hollow, bottomless, cylindrical body having a predetermined radial thickness and maintained in a vacuum state. The inner diameter and inner circumferential surface of the body are adapted to fit around the outer periphery of the tip end of an injector, while the outer diameter and outer circumferential surface of the body are adapted to be inserted into an injector mounting hole in an engine. Therefore, when the injector is mounted to an engine, the bottomless, cylindrical insulator maintained in a vacuum state is inserted between the outer periphery of the tip end of the injector and the engine. Therefore, the vacuum portion surrounding the outer periphery of the tip end of the injector blocks the transmission of vibrations, thereby reducing the transmission of vibrations generated when the injector is seated to the engine. [Effects of the Invention]

[0010] According to the present invention, it is possible to reduce the propagation of vibrations that occur when the injector is seated to the engine. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a block diagram showing the configuration of an engine equipped with an injector to which an insulator according to an embodiment is applied; [Figure 2] 1A and 1B are diagrams illustrating the configuration (structure) of an insulator according to an embodiment. [Figure 3] 1A and 1B are diagrams illustrating an insulator according to an embodiment and an injector vibration propagation reducing mounting structure using the insulator. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts will be designated by the same reference numerals. In addition, the same elements will be designated by the same reference numerals in each drawing, and redundant explanations will be omitted.

[0013] First, an insulator 30 according to an embodiment and an injector vibration propagation reducing mounting structure using the insulator 30 will be described with reference to Figures 1 to 3. Figure 1 is a block diagram showing the configuration of an engine 10 equipped with an injector 12 to which the insulator 30 is applied. Figure 2 is a diagram showing the configuration (structure) of the insulator 30. Figure 3 is a diagram showing the insulator 30 and an injector vibration propagation reducing mounting structure using the insulator 30.

[0014] The engine 10 is, for example, a horizontally opposed four-cylinder gasoline engine. The engine 10 is a direct injection engine that injects fuel directly into the cylinders. In the engine 10, air is drawn in through an air cleaner, throttled by a throttle valve provided in an intake pipe, passes through an intake manifold 11, and is drawn into each cylinder formed in the engine 10.

[0015] An injector 12 that injects fuel into each cylinder of the engine 10 is attached to each cylinder. The injector 12 directly injects fuel pressurized by a high-pressure fuel pump into the combustion chamber of each cylinder. An insulator 30 is inserted (press-fitted) between the engine 10 and the injector 12. Details of the insulator 30 will be described later.

[0016] Here, a known injector can be used as the injector 12. For example, as shown in Fig. 3, the injector 12 mainly includes a plunger (or needle valve) 12a, a solenoid coil (electromagnetic coil) 12b, a return spring 12c, and the like.

[0017] The plunger 12a is housed in a valve body 12e and is movable axially. The tip (valve member) of the plunger 12a is formed, for example, in a substantially spherical shape, and opens and closes the injection hole by moving toward and away from a valve seat 12d at the tip of the valve body 12e. When energized, the solenoid coil 12b attracts the plunger 12a axially backward (in the valve-opening direction) by electromagnetic force. The return spring 12c applies a biasing force to the plunger 12a axially forward (in the valve-closing direction).

[0018] When the solenoid coil 12b of the injector 12 is energized, the electromagnetic force of the solenoid coil 12b attracts the plunger 12a (driving it rearward in the axial direction) and moves it away from the valve seat 12d (opening the nozzle hole), thereby injecting fuel. On the other hand, when the solenoid coil 12b is de-energized, the urging force of the return spring 12c and the pushing force of the fuel pressure return the plunger 12a to the front in the axial direction, seating it on the valve seat 12d and closing the nozzle hole (i.e., stopping fuel injection). The operation of the injector 12 is controlled by the ECU 20.

[0019] Returning to Figure 1, the cylinder head of each cylinder is fitted with a spark plug 13 that ignites the air-fuel mixture, and an igniter-integrated coil 14 that applies high voltage to the spark plug 13. In each cylinder of the engine 10, the air-fuel mixture of intake air and fuel injected by the injector 12 is ignited by the spark plug 13 and combusted. Exhaust gas after combustion is discharged through an exhaust pipe 15.

[0020] A cam angle sensor 16 for identifying the cylinders of engine 10 is attached near the camshaft of engine 10. A crank angle sensor 17 for detecting the rotational position of crankshaft 10a is attached near the crankshaft 10a of engine 10. A timing rotor 17a having, for example, 34 protrusions with two teeth missing, formed at 10° intervals, is attached to the end of crankshaft 10a. Crank angle sensor 17 detects the presence or absence of the protrusions on timing rotor 17a to detect the rotational position of crankshaft 10a.

[0021] A knock sensor 27 is attached to the cylinder block of the engine 10 to detect vibrations caused by knocking (abnormal combustion) of the engine 10. When the engine 10 (cylinder block) vibrates, a weight built into the knock sensor 27 vibrates, and a force is applied to a piezoelectric element (piezoelectric ceramics), generating an electric signal. This is the principle by which the knock sensor 27 detects the vibrations of the engine 10. The knock sensor 27 is connected to the ECU 20.

[0022] Various sensors are also connected to the ECU 20, such as an accelerator operation amount sensor 22 that detects the amount of depression (operation amount) of the accelerator pedal, and a water temperature sensor 23 that detects the temperature (water temperature) of the cooling water. The ECU 20 is configured to include a microprocessor that performs calculations, an EEPROM that stores programs and the like for causing the microprocessor to execute various processes, a RAM that stores various data such as calculation results, a backup RAM in which the stored contents are maintained by a battery, and an input / output I / F. The ECU 20 also includes an injector driver that drives the injector 12, an output circuit that outputs an ignition signal, etc.

[0023] The ECU 20 identifies the cylinder from the output of the cam angle sensor 16, and determines the engine rotation speed from the output of the crank angle sensor 17. The ECU 20 also acquires various information such as the intake air amount, intake manifold pressure, accelerator pedal operation amount, air-fuel ratio of the air-fuel mixture, and water temperature and oil temperature of the engine 10 based on detection signals input from various sensors. The ECU 20 then comprehensively controls the engine 10 by controlling the fuel injection amount, ignition timing, and various devices based on the acquired information.

[0024] Incidentally, when the injector 12 closes, vibration occurs when the plunger 12a sits on the valve seat 12d. Therefore, the insulator 30 has a function of reducing the transmission of vibration generated when the injector 12 sits on the valve seat to the engine 10 (cylinder head and cylinder block).

[0025] 2 and 3, the insulator 30 includes a bottomless cylindrical main body (sleeve) 30a having a predetermined radial thickness, and the inside of the main body 30a is hollow and maintained in a vacuum state (or a substantially vacuum state). That is, a cylindrical hollow portion (vacuum portion) 30b is defined inside the main body 30a.

[0026] The inner diameter of the main body 30a is the same (or approximately the same) as the outer diameter of the tip of the injector 12, and the inner peripheral surface of the main body 30a is formed so as to be able to fit onto the outer periphery of the tip of the injector 12. The outer diameter of the main body 30a is also the same (or approximately the same) as the inner diameter of the injector mounting hole 10a of the engine 10 (cylinder head or cylinder block), and the outer peripheral surface of the main body 30a is formed so as to be able to be inserted (press-fit) into the injector mounting hole 10a of the engine 10. Therefore, the radial thicknesses of the main body 30a and the hollow portion (vacuum portion) 30b are set in accordance with the above requirements, etc.

[0027] The main body 30a is preferably made of a material having the same linear expansion coefficient as the engine 10 (cylinder head, etc.), such as an aluminum alloy or iron. However, the main body 30a may also be made of a heat-resistant engineering plastic or rubber, for example.

[0028] The insulator 30 can be manufactured in a vacuum manufacturing device by attaching one end surface (or the other end surface) of the main body 30a by welding or the like and then removing the device. However, the air in the hollow portion 30b may be evacuated after attaching one end surface (or the other end surface) in the atmosphere.

[0029] Here, since the source of vibration is near the tip of the injector 12 where the plunger 12a seats on the valve seat 12d, the main body portion 30a is formed so that when fitted onto the injector 12, it can cover at least the outer periphery of the side of the valve seat 12d (tip of the injector 12) where the plunger 12a of the injector 12 seats.

[0030] In particular, the axial length (dimension) of the main body 30a is preferably set (formed) so that, when fitted onto the injector 12, one end face (front end face) is flush or nearly flush with the front end face of the injector 12, and the other end face (rear end face) abuts against a stepped portion covering the solenoid coil 12b. However, it is preferable that one end face (front end face) of the main body 30a does not overlap the seating position of the plunger 12a as much as possible. In other words, it is preferable that the side surface of the seating position (vibration source) of the plunger 12a is covered with the vacuum section 30b.

[0031] Then, as shown in FIG. 3, the insulator 30 is inserted (press-fitted) between the engine 10 (cylinder head or the like) and the injector 12, thereby forming an injector vibration propagation reducing mounting structure.

[0032] As a result of the above-described configuration, namely, the interior of the bottomless cylindrical main body 30a is hollow and maintained in a vacuum state, the inner diameter and inner circumferential surface of the main body 30a are adapted to fit around the outer periphery of the tip end of the injector 12, and the outer diameter and outer circumferential surface of the main body 30a are adapted to be insertable into the injector mounting hole 10a of the engine 10. Therefore, when the injector 12 is mounted on the engine 10, the bottomless cylindrical insulator 30, the interior of which is maintained in a vacuum state, is inserted between the outer periphery of the tip end of the injector 12 and the engine 10. The vacuum portion 30b covering the outer periphery of the tip end of the injector 12 blocks the transmission of vibrations. This reduces the transmission of vibrations generated when the injector 12 is seated to the engine 10.

[0033] Furthermore, the above-described configuration prevents the knock sensor 27 from erroneously determining that the vibration of the injector 12 when seated is knocking, eliminating the need to mask the knock determination period (i.e., making it possible to set an optimal period), and therefore preventing engine performance from being restricted.

[0034] As described above in detail, according to this embodiment, when the injector 12 is attached to the engine 10, the bottomless cylindrical insulator 30, the interior of which is kept under vacuum, is inserted between the outer periphery of the tip of the injector 12 and the engine 10. The vacuum portion 30b that covers the outer periphery of the tip of the injector 12 blocks the propagation of vibrations. As a result, it is possible to reduce the propagation of vibrations that occur when the injector 12 is seated to the engine 10 (cylinder head, etc.).

[0035] Furthermore, according to this embodiment, it is possible to prevent the knock sensor 27 from detecting vibrations when the injector 12 is seated (falsely detecting it as knocking) and erroneously retarding the ignition timing. Therefore, it is possible to optimally set the knock determination period and the fuel injection period, and to avoid restrictions (constraints) on engine performance.

[0036] Furthermore, according to this embodiment, the insulator 30 (main body 30a) is formed to cover at least the outer periphery of the side surface of the valve seat 12d (tip of the injector 12) on which the plunger 12a is seated. Therefore, the outer periphery of the side surface of the seating position (location) of the plunger 12a, which is a vibration generating location, can be covered by the insulator 30 (main body 30a), the inside of which is kept under vacuum. Therefore, the transmission of vibrations generated when the injector 12 is seated to the engine 10 can be effectively reduced.

[0037] In particular, according to this embodiment, the axial length of the insulator 30 (main body 30a) is set so that, when fitted onto the injector 12, one end face (front end face) is flush (or substantially flush) with the front end face of the injector 12, and the other end face (rear end face) abuts against a stepped portion that covers the solenoid coil 12b of the injector 12. Therefore, the entire front end portion of the injector 12, including the seating position (location) of the plunger 12a, which is a vibration generating location, can be covered with the insulator 30 (main body 30a). This makes it possible to more effectively reduce the transmission of vibrations generated when the injector 12 is seated to the engine 10.

[0038] Although the present invention has been described above as an embodiment, it is not limited to the above embodiment and various modifications are possible. For example, although the above embodiment has been described as an example in which the present invention is applied to a direct injection engine (a direct injection engine), the present invention can also be applied to a port injection engine in which an injector is attached to an intake port.

[0039] Furthermore, in the above embodiment, the present invention has been described as being applied to a gasoline engine vehicle, but the present invention can also be applied to an engine (injector) of a hybrid vehicle (HEV) that uses an engine and a motor generator (MG) as a driving force source.

[0040] Furthermore, the dimensions, materials, etc. of the insulator 30 (main body portion 30a) described above are merely examples, and can be set or selected as desired according to requirements, etc. [Explanation of symbols]

[0041] 10 Engine 10a Injector mounting hole 12 injectors 12a plunger 12b Solenoid coil 12c return spring 12d Valve seat 12e valve body 17 Crank angle sensor 20 ECU 22 Accelerator operation amount sensor 23 Water temperature sensor 27 Knock sensor 30 insulator 30a Main body 30b Hollow part (vacuum part)

Claims

1. a cylindrical body portion having an open bottom and a predetermined radial thickness; The inside of the main body is hollow and maintained in a vacuum state, the inner diameter and inner circumferential surface of the main body are formed so as to be able to fit onto the outer periphery of the tip end of the injector; An insulator characterized in that the outer diameter and outer peripheral surface of the main body are formed so as to be insertable into an injector mounting hole of an engine.

2. 2. The insulator according to claim 1, wherein the main body is formed so as to cover at least the outer periphery of a side surface of a valve seat on which a plunger of the injector is seated when the main body is fitted onto the injector.

3. 3. The insulator according to claim 2, wherein the axial length of the main body is set so that, when fitted onto the injector, one end face is substantially flush with the tip end face of the injector, and the other end face abuts against a stepped portion that covers a solenoid coil of the injector.

4. 10. A mounting structure for reducing vibration transmission of an injector, wherein the insulator according to claim 1 is inserted between an engine and an injector.

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