JPH0319911B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an improvement in a fuel injection timing detection device for a fuel injection device that detects when fuel injection starts from a fuel injection valve of a diesel engine. be.

(Prior Art and its Problems) The present applicant has conventionally developed a fuel injection timing detection device as shown in FIG.

In this first prior example, a spring receiving member 102 supporting one end of a nozzle spring 100 receives a spring force of the nozzle spring 100 at a pressure receiving portion 10.
3a and a cylindrical support part 103b extending in the compression direction of the nozzle spring 100 continuously from the pressure receiving part 103a, and the spring receiving member 1
A piezoelectric element 104 is disposed within the support portion 103b of 02.

However, in the first precedent example, it is necessary to newly design the spring receiving member 102 of the injection valve, and the fuel injection timing detection device cannot be directly attached to the conventional injection valve, resulting in a problem of lack of compatibility. There is.

Changes in the load from the nozzle spring 100 are supported by both the piezoelectric element 104 and the support portion 103b, and there is also a problem in that the load acting on the piezoelectric element 104 decreases and the output of the piezoelectric element 104 decreases.

Furthermore, the piezoelectric element 104 is a nozzle spring 100.
Since the lift operation of the nozzle valve is sensed through the sensor, there is also a problem that the response of the piezoelectric element 104 is delayed.

Next, a second prior example (trade name: Needle Lift Sensor, manufactured by Orff Corporation) will be explained with reference to FIG.

In this second prior example, the Hall element 110 and the magnet 112 are connected to the spring seat 114 and the main body 11.
6, and the voltage of the output from the Hall element 110 is increased by an amplifier.

However, in the second prior example, since the output of the Hall element 110 is amplified by an amplifier, there is a problem that the response is delayed.

It is necessary to fix the magnet 112 to the spring seat 114, and it is not compatible with conventional injection valves.

Further, iron powder may adhere to the magnet 112, causing problems such as damage due to changes in the magnetic field or encroachment of dust.

(Objective of the Invention) The present invention provides a fuel injection device that can be installed as is without modification to a conventional fuel injection valve, has a large detection signal output, has good response, and is free from trouble. The purpose of this invention is to provide a timing detection device.

(Structure of the Invention) (1) Technical Means The present invention is a device for detecting the fuel injection start timing of a fuel injection valve, which comprises a body fixed along the axial direction of the fuel injection valve, and an inner periphery of the body. a slidable sensor bar that extends into the interior of the fuel injector and comes into contact with a member that interlocks with the nozzle valve of the fuel injector; and a spring that presses the piezoelectric element and the sensor bar against a member interlocking with the nozzle valve, and a change in the axial load of the piezoelectric element that occurs when the member interlocking with the nozzle valve lifts the fuel. This is a fuel injection timing detection device for a fuel injection device, characterized in that it detects injection start timing.

(2) Function Since it is installed in the axial direction of the body fuel injection valve,
There is no need to modify conventional injection valves, and the body can be easily installed.

Since the sensor bar directly transmits the load to the piezoelectric element, the load acting on the piezoelectric element increases and the output voltage from the piezoelectric element increases.

(Example) A fuel injection valve for a diesel engine equipped with a fuel injection timing detection device according to the present invention will be described with reference to FIG.

In FIG. 1, 10 is a fuel injection valve, and a fuel injection timing detection device 1 is provided at the head of the fuel injection valve 10.
2 is provided with compatibility maintained as will be described in detail later.

The fuel injection valve 10 has a substantially cylindrical nozzle holder 1
4, nozzle valve 17b, interspindle 1
8, a cap 20, etc.

The nozzle holder 14 is fixed to a cylinder head (not shown), and a joint 15a is provided on the side surface. A fuel feed pipe from a fuel injection pump, which will be described later, is connected to this joint 15a.

A nozzle body 16 is provided at the lower end of the nozzle holder 14.
is fixed with a mounting nut 17a, and a well-known nozzle valve 17b is provided inside the nozzle body 16. An interspindle 18 is in contact with the upper end of the nozzle valve 17b. The upper end of the interspindle 18 is a spring seat 19
is in contact with a. The spring seat 19a is urged downward by a nozzle spring 19d held by a spring case 19b via an upper spring receiver 19c.

A cap 20 is screwed onto the outer periphery of the spring case 19b, and a gasket 19e is inserted between the cap 20 and the body 14. cap 20
A screw hole 21a is formed in the center of the spring case 19b, and holes 19f and 19g are formed on the same central axis in the spring case 19b and the upper spring receiver 19c.

A spherical single-end joint 22 is provided directly above the screw hole 21a with upper and lower packings 23a and 23b interposed therebetween. Conventionally, this joint 22 is fixed to the cap 20 with a bolt B as shown in FIG.
The threaded portion 25a of the body 24 (FIG. 1) of the fuel injection timing detection device 12 is screwed into the hole 24a to attach the injection timing detection device 12 while maintaining compatibility. In addition, in Fig. 2, 26 is a fuel return pipe;
7 is a fuel feed pipe that supplies high-pressure fuel from the fuel injection pump P.

Next, details of the injection timing detection device 12, which is a main part of the present invention, will be explained with reference to FIGS. 1 and 3.

As shown in FIG. 1, this device 12 includes a substantially cylindrical body 24, a sensor bar 28, and a piezoelectric element 3.
0, a compression coil spring 32, etc.

The body 24 consists of a large diameter part 25b, a small diameter part 25c, etc., and inside the large diameter part 25b there is a piezoelectric element 30,
A compression coil spring 32 and the like are housed.
A sensor bar 28 is fitted inside the small diameter portion 25c in a vertically slidable manner, and
d penetrates in the radial direction. Also, the small diameter portion 25c
A threaded portion 25a is formed at the lower end.

An annular groove 23c is formed inside the joint 22 in communication with the passage 25d, and the annular groove 23c is connected to the discharge port 23.
It communicates with the fuel return pipe 26 via d.

The sensor bar 28 extends downward through the holes 19f and 19g, and the lower end of the sensor bar 28 is connected to the spring seat 19a (nozzle valve 17b).
(a member interlocking with) is in pressure contact with the upper surface of the

As shown in FIG. 3, a flange 33a and a protrusion 33b are formed at the upper end of the sensor bar 28, and the protrusion 33b is in close contact with the lower end surface of the cylindrical piezoelectric element 30. The piezoelectric element 30 is adhesively secured to a cylindrical sleeve 34 made of a non-conductive material.

A stopper 36 is in close contact with the upper end surface of the piezoelectric element 30. A compression coil spring 32 is compressed between the stopper 36 and the contact 38. The contact 38 is fixed to a nut 42 via a sleeve 40 made of a non-conductive material.
8 is electrically connected to the conducting wire 44. Note that the spring force of the compression coil spring 32 is set to be relatively weak, and the mass of the moving body consisting of the contact 38, piezoelectric element 30, sleeve 34, and sensor bar 28 is light enough not to inhibit the operation of the nozzle valve 17b. is set to .

Next, the effect will be explained. High-pressure fuel is pumped into the nozzle holder 14 from the fuel feed pipe 27 via the injection valve joint 15a, and is supplied into the nozzle body 16, where the fuel pressure opens the nozzle valve 17b and is injected into the combustion chamber. .

At this time, the interspindle 18 is pushed up by the nozzle valve 17b and the spring seat 19a
Make the lift work. When the spring seat 19a lifts, the sensor bar 28 of the injection timing detection device 12 is pressed and the piezoelectric element 3 is pressed by the projection 33b.
Hit 0.

Since the piezoelectric element 30 is directly struck by the protrusion 33b, a large output voltage is generated, and the start timing of fuel injection can be detected from the output signal from the piezoelectric element 30 without using additional equipment such as an amplifier. .

The output signal from the piezoelectric element 30 is sent to the outside through a conductive wire 44 through a stopper 36, a compression coil spring 32, and a contact 38.

Further, the surplus fuel supplied from the fuel feed pipe 27 (Fig. 2) rises through the inside of the nozzle holder 14, and is circulated through the annular groove 23c and the through hole 23d to the fuel return pipe 26 (Fig. 2). do.

Furthermore, the spring force of the coil spring 32 is smaller than that of the nozzle spring 19d, and the mass of the moving body consisting of the sensor bar 28, piezoelectric element 30, sleeve 34, and stopper 36 is also small, so the operation of the nozzle valve 17b is inhibited. There is no fear that

Moreover, the injection timing detection device 12 described above can be mounted on the threaded portion 25a of the body 24 by removing the bolt B shown in FIG.
It can be attached to the fuel injection valve 10 by simply screwing it into the screw hole 21a of the cap 20. Therefore, without making any modifications to the conventional fuel injection valve,
That is, the injection timing detection device 12 is installed while maintaining compatibility.

(Effects of the Invention) As explained above, the fuel injection timing detection device for a fuel injection device according to the present invention is a device for detecting the fuel injection start timing of a fuel injection valve, and is fixed along the axial direction of the fuel injection valve. a slidable sensor bar that is guided to the inner periphery of the body and extends into the inside of the fuel injection valve and contacts a member that interlocks with the nozzle valve of the fuel injection valve; A piezoelectric element provided to be pressed by a sensor bar, and a spring that presses the piezoelectric element and the sensor bar against a member interlocking with the nozzle valve, and a piezoelectric element generated when the member interlocking with the nozzle valve is lifted Since the fuel injection start timing is detected based on the change in the axial load of the element, the following effects are achieved.

First, when the nozzle valve 17b opens, the sensor bar 28 hits the piezoelectric element 30 via the interspindle 18 and the spring seat 19a, so the output voltage from the piezoelectric element 30 increases.

Therefore, there is no need to use an amplifier or the like as in the conventional case.

Since the sensor bar 28 directly hits the piezoelectric element 30, the responsiveness of the piezoelectric element 30 is improved, and the fuel injection start timing can be detected accurately.

Furthermore, since there is no need to use a magnet as in the conventional case, there is no risk of problems such as adhesion of iron powder.

Furthermore, remove the bolt B shown in Fig. 2 and remove the body 24.
The entire device 12 can be installed by simply attaching it, and it is compatible.

[Brief explanation of the drawing]

Fig. 1 is a vertical sectional view of a fuel injection device to which the present invention is applied, Fig. 2 is a perspective view thereof, Fig. 3 is an enlarged view of the main part of Fig. 1, and Figs. FIG. 10... Fuel injection valve, 17b... Nozzle valve, 19a... Spring seat, 12... Fuel injection timing detection device, 24... Body, 28... Sensor bar, 30... Piezoelectric element, 32... Compression coil spring.

Claims (1)

[Scope of Claims] 1. A device for detecting the fuel injection start timing of a fuel injection valve, which comprises a body fixed along the axial direction of the fuel injection valve, and a fuel injection valve guided by the inner circumference of the body. a slidable sensor bar that extends into the interior of the fuel injection valve and contacts a member that interlocks with the nozzle valve of the fuel injection valve; a piezoelectric element provided at the end of the sensor bar so as to be pressed by the sensor bar; and a spring that presses the sensor bar against a member interlocking with the nozzle valve, and the fuel injection start timing is detected by the change in the axial load of the piezoelectric element that occurs when the member interlocking with the nozzle valve lifts. A fuel injection timing detection device for a fuel injection device, characterized in that: 2. Claim 1, wherein the body is fixed to a bolt hole for fixing a fuel return oil pipe to a fuel injection valve.
A fuel injection timing detection device for the fuel injection device according to paragraph 1. 3. The fuel injection timing detection device for a fuel injection device according to claim 1, wherein the member interlocking with the nozzle valve of the fuel injection valve is a spring seat provided through an interspindle between the member and the nozzle valve. .