JP2013072292A - Safety valve with switch mechanism, and common-rail fuel injection control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable the opening/closing of a safety valve to be detected in a relatively simple construction, without depending on a pressure sensor.SOLUTION: At the end of a needle 22e extending from a valve element 22 to the opposite direction to a valve seat 23, a switch mechanism 101 is provided which is opened/closed depending on the seating/isolation of the valve element 22. The switch mechanism 101 has a movable contact member 31 and a contact energizing spring 33 formed of a conductive member arranged in a fixed contact member 32 formed of a conductive member. Conduction/non-conduction between a contact part 31a of the movable contact member 31, formed of a conductive member, and the fixed contact member 32 can be drawn to the outside via a columnar electrode 34, depending on the seating/isolation of the valve element 22 on/from the valve seat 23, and so the opening/closing of the safety valve 10 can be detected.

Description

  The present invention relates to a safety valve, and more particularly to an improvement in function of a safety valve used for discharging common rail high-pressure fuel to a low-pressure side.

A so-called common rail type fuel injection control device pressurizes fuel by a high pressure pump, pumps it to a common rail which is an accumulator, accumulates the pressure, and supplies the accumulated high pressure fuel to the injector. It is well known as being capable of fuel injection and excellent in fuel consumption, emission characteristics, and the like.
In such a common rail type fuel injection control device, a so-called mechanical safety valve is attached to the common rail, and when the rail pressure exceeds a predetermined threshold value, the safety valve is opened so that high pressure fuel can be discharged to the low pressure side. In many cases, a structure that ensures safety is adopted.

Since such a safety valve performs an important function for ensuring the safety of the common rail fuel injection control device, it is not possible to grasp whether the safety valve is in an open state or a closed state in fuel injection control. is important.
A so-called conventional mechanical safety valve itself does not have a function of outputting a valve opening / closing signal to the outside, so that, for example, a change in rail pressure detected by a pressure sensor provided in a common rail fuel injection control device Has proposed and put to practical use a method, a device and the like for detecting the opening / closing of the safety valve (see, for example, Patent Document 1).

JP 2008-50991 A (page 4-9, FIGS. 1 to 5)

However, in the method for detecting the opening / closing of the safety valve based on the change in the rail pressure detected by the pressure sensor, how to set the value or range of the rail pressure that is determined to be the opening / closing of the safety valve? However, since there are variations in the operating characteristics of individual devices, it is difficult to set them uniformly and it is necessary to set appropriate values for each device. There is a problem that it takes time and money to increase the price of the apparatus.
In addition, when the detection sensitivity of the pressure sensor is reduced, the rail pressure can be detected, but the detected value is not accurate. Therefore, a reliable and reliable safety valve can be opened and closed. There is a problem that detection cannot be guaranteed.
Furthermore, when the pressure sensor completely fails, there is a problem in that it is impossible to detect the opening / closing of the safety valve, which hinders the operation of the apparatus.

  The present invention has been made in view of the above circumstances, and a safety valve with a switch mechanism that enables detection of the opening and closing of a safety valve with a relatively simple configuration without relying on a pressure sensor, and a common rail fuel injection control A device is provided.

In order to achieve the above object of the present invention, a safety valve with a switch mechanism according to the present invention comprises:
A valve body and a valve body that can be seated on and separated from the valve seat, the valve body being pressed by a pressing spring in the valve seat direction to be seated on the valve seat; A seat having a flow path having an opening, and allowing the valve body to be separated from the valve seat against the pressing spring by the high-pressure fuel introduced through the flow path; When the valve body is separated from the valve seat by inflow, the high-pressure fuel can flow into the portion where the valve body is located through the valve seat and the valve body, and A safety valve capable of discharging the inflowed high-pressure fuel to a low-pressure side through a discharge path provided separately from the flow path on the side where the valve body is located;
A switch mechanism that opens and closes according to the seating and separation of the valve body is provided at the end of the needle extending from the valve body in the direction opposite to the valve seat.

According to the present invention, by providing a switch mechanism that opens and closes when the valve body is seated on and separated from the valve seat, the safety valve can be reliably opened and closed with a relatively simple configuration. By using the conventional device that detects the opening and closing of the safety valve based on the change in rail pressure by the pressure sensor, it is possible to reliably detect the opening and closing of the safety valve even when the pressure sensor fails. As a result, it is possible to take a quick suboptimal measure and to achieve a highly reliable common rail fuel injection control device.
The switch mechanism itself does not output an analog signal, but is configured to detect conduction and non-conduction between the fixed contact member and the moving contact member. Therefore, the switch mechanism can be opened and closed using a so-called digital input of a microcomputer. This makes it possible to make judgments, and unlike the switch mechanism itself that outputs an analog signal according to the opening and closing, setting adjustment of the judgment reference value in the microcomputer, so-called calibration work is not required, As a result, the cost can be reduced.

It is a block diagram which shows the structural example of the common rail type fuel injection control apparatus in which the safety valve with a switch mechanism in embodiment of this invention is used. It is a longitudinal cross-sectional view of the safety valve with a switch mechanism in embodiment of this invention. FIG. 3 is a partially enlarged longitudinal sectional view of a switch mechanism section in the safety valve with a switch mechanism shown in FIG. 2. FIGS. 4A and 4B are equivalent circuit diagrams when the switch mechanism of the safety valve with a switch mechanism according to the embodiment of the present invention is opened and closed, FIG. 4A is an equivalent circuit diagram when the valve is closed, and FIG. FIG. It is a subroutine flowchart which shows the procedure of the opening / closing success determination process of the switch mechanism performed by the electronic control unit used for the common rail type fuel injection control device shown in FIG.

Embodiments of the present invention will be described below with reference to FIGS. 1 to 5.
The members and arrangements described below do not limit the present invention and can be variously modified within the scope of the gist of the present invention.
First, a configuration example of a common rail fuel injection control device in which a safety valve with a switch mechanism according to an embodiment of the present invention is used will be described with reference to FIG.
The common rail fuel injection control device includes a high pressure pump device 50 that pumps high pressure fuel, a common rail 1 that stores the high pressure fuel pumped by the high pressure pump device 50, and high pressure fuel supplied from the common rail 1 to the engine 3. A plurality of fuel injection valves 2-1 to 2-n for supplying fuel to the cylinders, and an electronic control unit (indicated as "ECU" in FIG. 1) 4 for executing fuel injection control processing, opening / closing determination processing described later, and the like Is the main component.
Such a configuration itself is the same as the basic configuration of this type of fuel injection control apparatus that has been well known.

The high-pressure pump device 50 has a known and well-known configuration in which the supply pump 5, the metering valve 6, and the high-pressure pump 7 are configured as main components.
In this configuration, the fuel in the fuel tank 9 is pumped up by the supply pump 5 and supplied to the high-pressure pump 7 through the metering valve 6. As the metering valve 6, an electromagnetic proportional control valve is used, and the amount of energization is controlled by the electronic control unit 4, so that the flow rate of fuel supplied to the high-pressure pump 7, in other words, the discharge of the high-pressure pump 7. The amount is to be adjusted.

A return valve 8 is provided between the output side of the supply pump 5 and the fuel tank 9 so that surplus fuel on the output side of the supply pump 5 can be returned to the fuel tank 9. .
The supply pump 5 may be provided separately from the high-pressure pump device 50 on the upstream side of the high-pressure pump device 50 or may be provided in the fuel tank 9.
The fuel injection valves 2-1 to 2-n are provided for each cylinder of the engine 3, and are supplied with high-pressure fuel from the common rail 1, and perform fuel injection by injection control by the electronic control unit 4. Yes.

  The common rail 1 of the present invention is provided with a safety valve 10 in a return passage (not shown) for returning surplus fuel to the tank 9, and the rail pressure in the common rail 1 exceeds a predetermined pressure set in the safety valve 10. Then, the safety valve 10 is opened, and the fuel in the common rail 1 is discharged to the tank 9 through the low-pressure return passage (not shown), so that an inadvertent increase in the rail pressure is restricted. ing.

The electronic control unit 4 has, for example, a microcomputer (not shown) having a known and well-known configuration, a storage element (not shown) such as a RAM and a ROM, and a fuel injection valve 2- A drive circuit (not shown) for driving 1 to 2-n and an energization circuit (not shown) for energizing the metering valve 6 are configured as main components.
In addition to the detection signal of the pressure sensor 11 that detects the pressure of the common rail 1 being input to the electronic control unit 4, various detection signals such as the engine speed, the accelerator opening degree, and the fuel temperature are received from the engine 3. It is input for use in operation control and fuel injection control.

FIG. 2 shows a configuration example of the safety valve 10 with a switch mechanism according to the embodiment of the present invention. The configuration and the like will be described below with reference to FIG.
The safety valve 10 in the embodiment of the present invention has a casing 20, and a flow path 21 is formed in the casing 20 so as to communicate the inside of the casing 20 with the outside. A valve seat 23 in which the valve body 22 is seated and separated is formed at the opening portion, and the valve body 22 is disposed in the casing 20 together with the pressing spring 24 (details will be described later).

The casing 20 is composed of a main casing 20a formed in a generally low cylindrical shape, and a sub casing 20b fastened to the main casing 20a by caulking so as to close the opening of the main casing 20a. It has become.
In the main casing 20a, a first hollow portion 20a-1 and a second hollow portion 20a-2 are formed in order from the opening side opposite to the bottom portion 20a-3. The first hollow portion 20a-1 Is formed larger in diameter than the second hollow portion 20a-2. The 1st hollow part 20a-1 forms the accommodating part 20c in which the flange part 22b of the valve body 22 is accommodated with the hollow part 20b-1 of the subcasing 20b mentioned later.
A caulking piece 20d formed relatively thin is extended from the peripheral edge of the opening side of the main casing 20a to the side opposite to the opening, and is caulked to the outer periphery of the end of the sub casing 20b as will be described later. It has become.

The second hollow portion 20a-2 accommodates a pressing spring 24 so that the valve body 22 can be biased toward the valve seat 23.
Furthermore, the main casing 20a has a communication hole 20a− so as to communicate the inside and the outside of the main casing 20a with a portion located in the low pressure chamber 45 when attached to a valve connection portion 41 of the common rail 1 described later. 4 is perforated.
Furthermore, on the outer peripheral surface of the main casing 20a, when attached to a valve connecting portion 41 of the common rail 1 to be described later, a portion located slightly on the bottom 20a-3 side than a portion located in the low pressure chamber 45 The male screw 20e for valve connection is formed. On the other hand, a female screw 43a for valve connection is formed on a part of an inner peripheral surface of a later-described valve connection chamber 43 corresponding to the male screw 20e for valve connection. The valve connecting male screw 20e and the valve connecting female screw 43a are screwed to the valve connecting portion 41.

On the other hand, the sub-casing 20b is generally the same as the main casing 20a in that it is formed in a low-cylindrical shape. However, the point that the hollow portion 20b-1 is formed flat is different from the main casing 20a. Yes. The hollow portion 20b-1 is set to have the same inner diameter as the first hollow portion 20a-1 of the main casing 20a, and the end surface of the sub casing 20b on the hollow portion 20b-1 side and the first hollow portion of the main casing 20a. The end surface on the 20a-1 side is joined, and the storage portion 20c is defined by the first hollow portion 20a-1 and the hollow portion 20b-1.
And the flow path 21 is formed in the center of the bottom part of the hollow part 20b-1, so that the subcasing 20b may be penetrated, and the hollow part 20b-1 side and the fuel introduction chamber 42 side can be connected. It has become.

Further, a valve seat 23 on which the valve body 22 is seated is formed in a tapered shape at the opening portion of the flow path 21 on the hollow portion 20b-1 side, and the valve body 22 is seated and separated as will be described later. It has become a thing.
Further, in the vicinity of the peripheral edge of the end portion on the opposite side to the end portion where the hollow portion 20b-1 of the sub casing 20b in the embodiment of the present invention is located, an edge 20f is formed in the longitudinal direction of the safety valve 10 in the hollow portion 20b-1. The seat portion 26 is formed together with the seat step 44 of the valve connecting portion 41 as will be described later.
For example, the edge 20f is preferably formed to project in an annular shape.

  The valve body 22 has a columnar connecting portion 22a formed in a columnar shape, and a disc-shaped flange portion 22b is formed on one end side thereof, while the other end side is formed in a generally hemispherical shape to form a seat portion 22c. Thus, it is easy to sit on the valve seat 23. A fuel circulation hole 22d is drilled at an appropriate position in the flange portion 22b.

  A needle 22e extends from the center portion of the flange portion 22b of the valve body 22 in the direction opposite to the columnar connecting portion 22a. The needle 22e has a length in the longitudinal axis direction (the columnar connecting portion 22a is located on the left side and the bottom portion 20a-3 of the main casing 20a is located on the right side as viewed in FIG. 2). The length is set slightly shorter than the length of the main casing 20a in the same direction, and will be described later between the end located on the side opposite to the columnar connecting portion 22a and the bottom 20a-3 of the main casing 20a. Is provided with a switch mechanism 101.

Next, the switch mechanism 101 will be described mainly with reference to FIG.
The switch mechanism 101 in the embodiment of the present invention is provided between the end portion of the needle 22e and the bottom portion 20a-3 of the main casing 20a.
The switch mechanism 101 is composed of a moving contact member 31, a fixed contact member 32, and a contact biasing spring 33 as main components.

The moving contact member 31 includes a contact portion 31a formed in a generally ring shape, and an end contact portion 31b formed in a generally concave shape in the ring-shaped opening and projecting on one surface side. The contact portion 31a is formed of a conductive member, and the end contact portion 31b is formed of an insulating member (see FIG. 3).
The moving contact member 31 is urged toward the valve seat 23 by a contact urging spring 33, and when the valve body 22 is seated on the valve seat 23, as will be described later. The contact portion 31a contacts the fixed contact member 32 with a slight gap between the needle 22e and the end contact portion 31b. Here, the slight gap between the needle 22e and the end contact portion 31b is set to be sufficiently smaller than the lift amount of the valve body 22. When the valve element 22 is separated from the valve seat 23, the end of the needle 22 e comes into contact with the end contact part 31 b, and the moving contact member 31 resists the urging force of the contact urging spring 33. The fixed contact member 32 can be separated from the fixed contact member 32.

  Note that the outer diameter of the contact portion 31a formed in a ring shape is the inner circumference of the fixed contact member 32 described below when the moving contact member 31 is displaced along with the axial movement of the needle 22e as will be described later. It is set to an appropriate size smaller than the inner diameter of the fixed contact member 32 so as to maintain a sufficient distance from the inner peripheral surface without contacting the surface.

The fixed contact member 32 is formed in a generally hollow cylindrical shape using a conductive member, and an annular flange 32a is formed in the opening portion.
A needle through-hole 32c is drilled in the center of the bottom 32b of the fixed contact member 32 so that the needle 22e can be penetrated as will be described later.
The fixed contact member 32 is fixed so that the annular flange 32a is joined to the bottom portion 20a-3 of the main casing 20a. At that time, the fixed contact member 32 is moved in order from the bottom portion 32b side. The contact member 31 and the contact urging spring 33 are accommodated.

Here, the outer diameter of the contact urging spring 33 is set to be substantially the same as the outer diameter of the contact portion 31 a formed in a generally ring shape of the moving contact member 31.
When the contact urging spring 33 is housed together with the moving contact member 31 in the fixed contact member 32, the end of the contact urging spring 33 comes into contact with the contact portion 31a.
Further, the length of the needle 22e in the longitudinal axis direction and the length of the fixed contact member 32 along the longitudinal axis direction of the needle 22e are appropriately set, so that the valve body 22 is seated on the valve seat 23. The contact portion 31a is brought into contact with the fixed contact member 32 in a state where a slight gap is generated between the end contact portion 31b of the moving contact member 31 and the end portion of the needle 22e. On the other hand, when the valve element 22 is separated from the valve seat 23, the end portion of the needle 22e is in contact with the end contact portion 31b, and the contact portion 31a is against the biasing force of the contact biasing spring 33. It can be separated from the fixed contact member 32.

  On the other hand, a connector connecting screw hole 20a-5 formed in a columnar shape for connecting a connector 27 to be described later is drilled in the bottom portion 20a-3 of the main casing 20a to which the fixed contact member 32 is fixed. The connector connecting screw hole 20a-5 is set to have an inner diameter slightly larger than the inner diameter of the fixed contact member 32, and the inner opening portion from the inner side of the main casing 20a to the inner side of the outer opening portion is slightly ahead. A female screw 20a-6 for connector connection is formed on the peripheral surface, and an annular step 20a-7 for disposing the O-ring 38 is formed on the outer opening.

  The connector 27 has an electrode holding member 35 made of an insulating member and a columnar electrode 34 made of a conductive member. The electrode holding member 35 includes a screw connection portion 35a inserted into and screwed into the connector connecting screw hole 20a-5, a nut portion 35b having a diameter larger than the outer diameter of the screw connection portion 35a, and a screw connection portion. A mantle portion 35c having an outer diameter larger than the outer shape of 35a and smaller than the outer diameter of the nut portion 35b is integrally formed.

  The screw connection portion 35a is formed in a columnar shape, and on the outer peripheral surface thereof, a connector connection male screw 35a-1 that is screwed into the connector connection female screw 20a-6 is formed to the vicinity of the nut portion 35b. An O-ring 38 is externally fitted to a portion in the vicinity of the nut portion 35b where the connector connecting male screw 35a-1 is not formed. With this O-ring 38, when the connector connecting male screw 35a-1 is screwed into the connector connecting female screw 20a-6 and the connector 27 is connected to the main casing 20a, the airtightness between the safety valve 10 and the switch mechanism 101 is improved. Sex is to be maintained.

When the male screw 35a-1 for connector connection and the female screw 20a-6 for connector connection are screwed together and the connector 27 is connected to the main casing 20a, the nut portion 35b is just attached to the bottom 20a-3 of the main casing 20a. It is formed in the position where it abuts and fulfills the same function as a nut.
In the screw connection portion 35a and the nut portion 35b, an electrode through hole 35d is drilled so as to penetrate the screw connection portion 35a and the nut portion 35b along the central axis direction (the left-right direction in FIG. 3). A columnar electrode 34 is embedded.

The columnar electrode 34 in the embodiment of the present invention is formed in a roughly columnar shape using a conductive member, and its axial length is set to a sufficient length that penetrates the electrode through-hole 35d, In the vicinity of one end, an annular contact flange 34a having an outer diameter substantially the same as the outer diameter of the contact urging spring 33 is provided.
Corresponding to the outer shape of the columnar electrode 34, the electrode through-hole 35d has an inner diameter set to be substantially equal to the outer diameter of the portion excluding the annular contact flange 34a of the columnar electrode 34. A flat large-diameter portion 35e into which the annular contact flange 34a is fitted is formed on one end portion side, that is, an end portion located on the inner side of the main casing 20a.
Further, the outer cover portion 35c is formed in a generally hollow cylindrical shape, and protects a part of the columnar electrode 34 located in the hollow portion as described below.

Thus, the end of the columnar electrode 34, that is, the end opposite to the annular contact flange 34a, is inserted into the electrode through hole 35d from the flat large diameter portion 35e. As a result, the annular contact flange 34a is fitted into the flat large diameter portion 35e so as to be integrated.
In such a state, the end of the columnar electrode 34 on the side opposite to the annular contact flange 34a is positioned approximately at the center in the central axis direction (left and right direction in FIG. 3) of the outer cover portion 35c. .

  In order to attach the connector 27 to the main casing 20a, first, the O-ring 38 is externally fitted at a position where the male screw 35a-1 for connector connection is not formed at the position on the nut portion 35b side of the screw connection portion 35a. Then, the tip end of the screw connection portion 35a is inserted into the connector connection screw hole 20a-5 from the bottom 20a-3 side of the main casing 20a, and the connector connection male screw 35a-1 portion is connected to the connector connection female screw 20a. At the point of contact with the -6 portion, the entire connector 27 is slowly turned clockwise to screw the connector connecting male screw 35a-1 and the connector connecting female screw 20a-6 together. Then, just after the male screw 35a-1 for connector connection and the female screw 20a-6 for connector connection are finished, the nut portion 35b is joined to the bottom portion 20a-2 (see FIG. 3), and the connector 27 is The main casing 20 is attached to the bottom 20a-3.

  Thus, in the state where the connector 27 is attached to the main casing 20a, the fixed contact member 32, the moving contact member 31, and the contact biasing spring 33 are provided on the inner side of the main casing 20a as described above. When attached, the end of the contact biasing spring 33 on the columnar electrode 34 side is always in contact with the annular contact flange 34a.

The safety valve 10 is connected to a valve connecting portion 41 provided on the common rail 1 so that the high-pressure fuel in the common rail 1 can flow in through the flow path 21 (see FIG. 2).
That is, the valve connection portion 41 is formed in a roughly columnar shape in its outline appearance, and the inside thereof is formed in a hollow shape, and the fuel introduction chamber 42 filled with the high-pressure fuel of the common rail 1 in the longitudinal axis direction. The valve connection chamber 43 into which the safety valve 10 is inserted is divided into two.
A seat step 44 is annularly formed between the fuel introduction chamber 42 and the valve connection chamber 43, and the inner diameter of the inner peripheral surface of the seat step 44 is the outer diameter of the sub casing 20 b of the safety valve 10. It is set slightly larger (see FIG. 2).
The edge portion 20f of the sub-casing 20b described above comes into contact with the seat step portion 44 to form a seat portion 26 so as to prevent fuel leakage from the fuel introduction chamber 42 to the valve connection chamber 43 side. It has become.

In the valve connection chamber 43, a hollow portion having an inner diameter substantially the same as the outer diameter of the main casing 20a is formed from the end opposite to the fuel introduction chamber 42, and a part of the vicinity of the seat step 44 is formed. The inner diameter of the part is set to be larger than the outer diameter of the main casing 20 a, and the low pressure chamber 45 is defined between the safety valve 10 and the part.
When the safety valve 10 is attached to the valve connection chamber 43, the low pressure chamber 45 is in a position where the communication hole 20a-4 drilled in the main casing 20a faces.

And the external connection hole 25 is pierced at an appropriate position in the portion of the valve connection portion 41 where the low pressure chamber 45 is formed, and the high pressure discharged from the communication hole 20a-4 of the safety valve 10 to the low pressure chamber 45. The fuel is guided to a connection path (not shown) to the fuel tank 9 (see FIG. 1) through the external connection hole 25.
Further, in the embodiment of the present invention, a part of the inner peripheral surface of the valve connection chamber 43 having an inner diameter substantially the same as the outer diameter of the main casing 20 a constituting the safety valve 10, that is, immediately before moving to the low pressure chamber 45. A valve connection female screw 43a is formed in the part, and a valve connection male screw 20e that is screwed with the valve connection female screw 43a is formed in a part of the outer peripheral surface of the corresponding main casing 20a.

Accordingly, the safety valve 10 is inserted into the valve connection chamber 43 from the side of the sub casing 20b, and the entire safety valve 10 is rotated in the clockwise direction after the above-described male screw 20e for valve connection is positioned slightly in front of the female screw 43a for valve connection. Turn the valve connecting male screw 20e and the valve connecting female screw 43a, and when the leading edge 20f contacts the seat step 44, the mounting of the safety valve 10 to the valve connecting portion 41 is completed. It is supposed to be.
In the embodiment of the present invention, the outer surface of the main casing 20a of the safety valve 10 is close to the end of the valve connecting portion 41 when the safety valve 10 is attached to the valve connecting portion 41 as described above. On the other hand, the valve contact flange 20a-8 is integrally formed at a position where the valve contact flange 20a-8 protrudes. On the end face of the valve connection portion 41, an O-ring disposing step 41b is formed, and the safety valve 10 is described above. Thus, when attached to the valve connection portion 41, the valve connection O-ring 46 can be arranged in the gap formed between the O-ring arrangement step portion 41b and the outer peripheral surface of the main casing 20a. ing. As a result, fuel leakage from the low pressure chamber 45 to the outside is prevented.

  In the state where the safety valve 10 is attached to the valve connection portion 41 as described above, the force that acts to separate the valve body 22 from the valve seat 23 by the high-pressure fuel is applied to the pressure spring 24 set in advance with respect to the valve body 22. In a state where the urging force is not exceeded, it is a matter of course that the valve body 22 is seated on the valve seat 23. In this state, in the switch mechanism 101, the contact portion 31a of the moving contact member 31 is brought into contact with the fixed contact member 32 by the contact biasing spring 33. A gap sufficiently smaller than the lift amount of the needle 22e is generated between the portion contact portion 31b and the needle 22e.

When the pressure of the high pressure fuel exceeds the urging force of the pressing spring 24 against the valve body 22, the valve body 22 is separated from the valve seat 23, and the high pressure fuel passes through the gap between the valve body 22 and the valve seat 23 from the flow path 21. Then, it flows into the main casing 20a through the fuel circulation hole 22d. The high-pressure fuel that has flowed into the main casing 20a flows into the low-pressure chamber 45 from the communication hole 20a-4, and is returned from the low-pressure chamber 45 to the fuel tank 9 through a pipe (not shown) through the external connection hole 25. ing.
At this time, in the switch mechanism 101, the moving contact member 31 is separated from the fixed contact member 32 due to the displacement of the needle 22e accompanying the separation of the valve body 22 from the valve seat 23, and the switch mechanism 101 is opened. It will be detected by the electronic control unit 4 as described below.

Next, the operation of the switch mechanism 101 in the safety valve with a switch mechanism according to the embodiment of the present invention having the above-described configuration and the detection process by the electronic control unit 4 for opening and closing the same will be described with reference to FIGS. . In the following description, FIGS. 2 and 3 are also referred to as needed.
First, opening / closing of the switch mechanism 101 can be detected between the columnar electrode 34 and the ground.
That is, the fixed contact member 32 is electrically connected to the main casing 20a and the valve connecting portion 41, and the valve connecting portion 41 is connected to the ground (see FIG. 2).

On the other hand, the columnar electrode 34 is always electrically connected to the contact portion 31a of the moving contact member 31 via the contact biasing spring 33, and a pull-up circuit 60 provided in the electronic control unit 4 is provided. 4 is connected to a digital input port (indicated as “INd” in FIG. 4) of a microcomputer (indicated as “CPU” in FIG. 4) (see FIG. 4).
That is, the pull-up circuit 60 includes a first pull-up resistor 61 and a second pull-up resistor 62 connected in series between a battery power source (not shown) and the ground. The columnar electrode 34 is connected to a connection point between the two resistors 61 and 62 by a wiring (not shown) and is connected to the digital input port INd of the microcomputer 4a. Yes.

As described above, in the switch mechanism 101, when the pressure of the high-pressure fuel does not exceed the urging force of the pressing spring 24 and the valve element 22 is seated on the valve seat 23, the moving contact member 31 is fixed. It will be in the state contact | abutted to the contact member 32. FIG. In this state, the columnar electrode 34 is connected to the ground via the contact urging spring 33, the contact portion 31 a of the moving contact member 31, the fixed contact member 32, the main casing 20 a, and the valve connection portion 41. The Rukoto.
Therefore, electrically, as shown in FIG. 4A, the switch mechanism 101 is closed, and the connection point between the pull-up first and second resistors 61 and 62 is At the same time, the digital input port INd of the microcomputer 4a also becomes the ground potential.

On the other hand, when the pressure of the high pressure fuel exceeds the urging force of the pressing spring 24 and the valve body 22 is separated from the valve seat 23, the end of the needle 22e comes into contact with the end contact portion 31b, and the moving contact The member 31 is separated from the fixed contact member 32, whereby the electrical conduction state between the columnar electrode 34 and the fixed contact member 32 through the contact urging spring 33 and the moving contact member 31 is cut off. .
Therefore, since the switch mechanism 101 is in the open state, the potential at the connection point between the first and second pull-up resistors 61 and 62 is determined by the resistance of the power source voltage VB by the two resistors 61 and 62. The divided value is obtained (see FIG. 4B). The resistance partial pressure value can be set to a desired magnitude by appropriately selecting the resistance values of the two resistors 61 and 62, and the switch mechanism 101 in the electronic control unit 4 to be described later can be opened and closed. It is possible to set a value suitable for the determination process.

FIG. 5 shows a subroutine flowchart showing the opening / closing determination processing procedure of the switch mechanism 101 executed by the electronic control unit 4, and the contents thereof will be described below with reference to FIG.
First, the subroutine flowchart shown in FIG. 5 shows the subroutine processing executed together with the various vehicle operation control processing executed by the microcomputer 4a of the electronic control unit 4, for example, fuel injection control processing. It is one.

Thus, when processing is started by the microcomputer 4a, it is first determined whether or not the voltage Vp of the digital input port INd exceeds a predetermined threshold value K (see step S202 in FIG. 5). ).
Here, the predetermined threshold value K is the input port voltage as the voltage at the connection point between the resistors 61 and 62 when the switch mechanism 101 is in the open state (see FIG. 4B) as described above. This is the voltage to be detected at INd.

If it is determined in step S202 that Vp> K (in the case of YES), it is determined that the safety valve 10 is in an open state (see step S204 in FIG. 5), while Vp> K is not satisfied. If it is determined (NO), it is determined that the safety valve 10 is in a closed state (see step S206 in FIG. 5).
After the process of step S204 or step S206, the process once returns to the main routine (not shown).

Here, the determination result obtained in steps S204 and S206 as to whether the safety valve 10 is in an open state or a closed state is referred to in a failure determination process or the like in the main routine as described below. .
That is, as described above, the common rail fuel injection control device (see FIG. 1) according to the embodiment of the present invention includes the pressure sensor 11 and the rail in the common rail 1 detected by the pressure sensor 11 as in the prior art. It is assumed that the basic principle is to determine whether the safety valve 10 is open or closed based on a change in pressure.

  In the common rail fuel injection control apparatus according to the embodiment of the present invention, in addition to the determination of the opening and closing of the safety valve 10 based on the rail pressure detected by the pressure sensor 11, the opening of the switch mechanism 101 described above, By performing the closing determination process, the reliability of the determination of the opening and closing of the safety valve 10 is made higher than in the past.

  That is, when it is determined that the safety valve 10 is in the closed state by the detection of the rail pressure by the pressure sensor 11, a determination result that the safety valve 10 is in the closed state is obtained at the same time as described in FIG. If it is determined (see step S206 in FIG. 5), since the two determination results match, it is possible to place high confidence in the determination that the safety valve 10 is in the closed state. This is the same even when the safety valve 10 is open.

On the other hand, the determination result of whether the safety valve 10 is opened or closed based on the detection of the rail pressure by the pressure sensor 11, and the determination result of whether the safety valve 10 is opened or closed by opening / closing the switch mechanism 101 However, if either of the pressure sensor 11 and the switch mechanism 101 is suspected, the engine 3 is suspected of malfunctioning. For example, based on the operating status of the engine 3, specifically, the engine speed, the fuel injection amount, etc. If there is no particular abnormality in the operation of 3, it is more suspected that the pressure sensor 11 is faulty.
Therefore, in this case, it can be notified that the pressure sensor 11 is out of order, and is earlier than the conventional device in which the determination of the opening and closing of the safety valve 10 is performed only by the pressure sensor 11. In addition, it is possible to take an appropriate response, which contributes to ensuring high safety and reliability of the vehicle.

  As described above, in the embodiment of the present invention, the case where the switch mechanism 101 is used as an auxiliary to the pressure sensor 11 has been described. Of course, instead of the pressure sensor 11, only the switch mechanism 101 is used. A configuration for determining whether the safety valve 10 is open or closed may be used.

  It is suitable for a safety valve that is desired to enable more reliable detection of the opening and closing states of a safety valve and a common rail fuel injection control device using the safety valve.

DESCRIPTION OF SYMBOLS 10 ... Safety valve 31 ... Moving contact member 32 ... Fixed contact member 33 ... Contact biasing spring 34 ... Columnar electrode 101 ... Switch mechanism

Claims (4)

A valve body and a valve body that can be seated on and separated from the valve seat, the valve body being pressed by a pressing spring in the valve seat direction to be seated on the valve seat; A seat having a flow path having an opening, and allowing the valve body to be separated from the valve seat against the pressing spring by the high-pressure fuel introduced through the flow path; When the valve body is separated from the valve seat by inflow, the high-pressure fuel can flow into the portion where the valve body is located through the valve seat and the valve body, and A safety valve capable of discharging the inflowed high-pressure fuel to a low-pressure side through a discharge path provided separately from the flow path on the side where the valve body is located;
A safety valve comprising a switch mechanism that opens and closes according to seating and separation of the valve body at an end of a needle extending from the valve body in a direction opposite to the valve seat. The switch mechanism includes a moving contact member that is displaced according to the movement of the needle, and a fixed contact member that is fixed at a predetermined position in the displacement direction of the moving contact member, and constantly biases the moving contact member toward the valve body. A contact energizing spring is provided,
The moving contact member has an end contact portion that enables contact with the end portion of the needle on the side opposite to the valve body, and a contact portion that enables contact with the fixed contact member. ,
The fixed contact member is fixed at a position where the valve element is in contact with the contact portion of the moving contact member in a state where the valve body is seated on the valve seat, and at least the contact portion of the moving contact member, the fixed contact member The contact urging spring uses a conductive member, and the contact portion of the moving contact member and the fixed contact member come into contact with and separate from each other as the valve body is seated on and separated from the valve seat. 2. The safety valve according to claim 1, wherein the safety valve is configured to be able to generate a conductive / non-conductive state between the contact portion of the moving contact member and the fixed contact member. The fuel in the fuel tank is pressurized and pumped to the common rail by a high-pressure pump, and high-pressure fuel can be injected into the engine via a fuel injection valve connected to the common rail, and the rail pressure of the common rail is controlled by an electronic control unit. The common rail fuel injection control device is provided with a safety valve that can be controlled, and is provided with a safety valve that opens when the rail pressure exceeds a predetermined pressure and allows fuel to be released to the low pressure side. ,
The safety valve includes a valve seat and a valve body that can be seated on and separated from the valve seat, and the valve body is pressed by a pressing spring in the valve seat direction so as to be seated on the valve seat. On the other hand, the valve seat is formed and has a channel having an opening, and the valve body can be separated from the valve seat against the pressing spring by the high-pressure fuel introduced through the channel, When the valve body is separated from the valve seat by the inflow of the high-pressure fuel, the high-pressure fuel can flow into the part where the valve body is located between the valve seat and the valve body. In addition, it becomes possible to discharge the high-pressure fuel introduced into the low-pressure side through a discharge path provided separately from the flow path on the side where the valve body is located,
A common rail fuel injection control device, wherein a switch mechanism that is opened and closed according to seating and separation of the valve body is provided at an end of a needle extending from the valve body in a direction opposite to the valve seat. . The switch mechanism includes a moving contact member that is displaced according to the movement of the needle, and a fixed contact member that is fixed at a predetermined position in the displacement direction of the moving contact member, and constantly biases the moving contact member toward the valve body. A contact energizing spring is provided,
The moving contact member has an end contact portion that enables contact with the end portion of the needle on the side opposite to the valve body, and a contact portion that enables contact with the fixed contact member. ,
The fixed contact member is fixed at a position where the valve element is in contact with the contact portion of the moving contact member in a state where the valve body is seated on the valve seat, and at least the contact portion of the moving contact member, the fixed contact member The contact urging spring uses a conductive member, and the contact portion of the moving contact member and the fixed contact member come into contact with and separate from each other as the valve body is seated on and separated from the valve seat. 4. The common rail fuel injection control device according to claim 3, wherein a conductive state and a non-conductive state can be generated between the contact portion of the moving contact member and the fixed contact member.

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