JPH03175143A - Fuel injection device - Google Patents

Abstract

PURPOSE:To prevent differences in the amount of fuel injected due to errors in the manufacture of a fuel injection device by forming a rectilinear channel for regulating the timing of the start of forcible feed of pressurized fuel of a pressure chamber in response to closing of a ring-shaped member by an overflow port regardless of the relative distance between the overflow port and a low-pressure port. CONSTITUTION:A reed 101 for deciding the start of injection of fuel is newly provided on the inner peripheral face of a ring-shaped member 7 in such a manner as being balanced and parallel to the generating line of the inner peripheral face. Since either one of overflow ports 71 to 74 agrees with the reed 101, fuel in a pump chamber 2 leaks to low pressure and pressure will not be raised even when force feed plungers 21, 22 are sent to force feed process by a cam mechanism. When a fuel distribution rotating member 4 rotates and either one of the ports 71 to 74 is disconnected from the reed 101 and comes to an (e) position, fuel pressure within the pump chamber 2 is raised and the force feed of fuel is started and injection of the fuel is developped. When the member 4 further rotates and one of the port comes to an (f) position where it agrees with a diagonal reed 100, high-pressure fuel overflows and injection of the fuel is finished; i.e. the angle of the cam is always constant from start to finish of the force feed of the fuel.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fuel injection amount device that pressurizes and pumps fuel.

[Prior Art] In general, a fuel injection amount device has a moving member that is driven by an engine to perform periodic reciprocating or rotating motion, and the movement of this member is used to pressurize and pump fuel into a pump chamber. Is going.

In addition, in this type of fuel injection amount device, an overflow port that communicates with the pressure chamber is formed on the outer peripheral surface of the above-mentioned moving member, and a ring-shaped member is arranged to close the overflow port. By moving the member in the axial direction, the injection amount or injection timing is adjusted using the movement of the moving member.

Furthermore, in this type of fuel injection amount device, the overflow port of the above-mentioned moving member is communicated with a low pressure port or low pressure groove that communicates with the low pressure side, so that the pressurized fuel in the pump chamber overflows to the low pressure side and is injected. At the same time, by forming either the overflow port or the low pressure port as an inclined groove, the relative position between the pressure capo (and the low pressure port) can be adjusted, and the injection amount can be adjusted by adjusting this relative position. It is carried out.

Based on the above-mentioned known technology, the present inventors have developed and filed an application for the following fuel injection amount device.

The invention under application will be described below based on specific examples with reference to FIGS. 1-1 to 4-2.

In addition, Fig. 1-1 is a cross-sectional configuration diagram along the central axis of the inner cam type pump developed by the inventors, and Fig. 1-2 is a cross-sectional view taken along the line A-A in Fig. 1-1. Fig. 13 is B in Figure 1-1.
-B sectional view and FIG. 1-4 are schematic perspective views showing the main parts of FIG. 1-1 in an easy-to-understand manner, and the same members as in FIG. 1-1 are given the same reference numerals.

As is well known, a fuel distribution rotating member 4 is periodically and continuously driven to rotate inside an inner cam 1 fixed to a housing O at 1/2 the rotation speed of an engine (not shown). (This embodiment discloses a case in which the present invention is applied to a four-cylinder engine.) Due to the rotation, the pressure-feeding plunger 2122, which is housed so as to be slidable in the radial direction in the rotating surface of the fuel distribution rotating member, moves toward the cam 1. It reciprocates periodically according to the profile and compresses the fuel in the pump chamber 2. The compressed fuel passes through the introduction hole 3 communicating with the pump chamber 2, reaches the distribution port 6, and is connected to the fuel supply passage 61 to each matched cylinder according to the rotation.
The fuel is injected from 1 to 64 to each cylinder of the engine via a suction valve 601 and an injection valve (not shown).

Note that, prior to the pressure feeding of fuel oil by the plungers 21 and 22, a feed pump 3 is installed in the pump chamber 2 and the guide hole 3.
The fuel pre-pressurized at 00 is supplied to the supply port 5 and the suction hole 51.
to 54 and then inhaled.

In addition, overflow ports 71 to 74 communicating with the pump chamber 2 and the guide hole 3 are provided in the rotating member 4, and are fitted in the rotating member 4 in an oil-tight manner and are slidable in the axial direction of the rotating member 4. A ring-shaped member 7 that can be freely attached is provided, and one end of the inner peripheral surface of the ring-shaped member is inclined with respect to the generatrix of the inner diameter cylinder of the ring member. It has a lead-shaped groove 10 as a low-pressure port formed to be electrically conductive.

In addition, FIG. 2-1 shows a cross-sectional view taken along the line C-C in FIG. show.

The operation of controlling the fuel injection amount by overflow adjustment with the above configuration will be explained below with reference to FIGS. 3-1 to 4-2.

In FIG. 3-1, when one of the overflow ports 71 to 74 in the relevant cylinder reaches position a in FIG. 3-2, which is a developed view of the inner peripheral surface of the ring-shaped member 7, the plunger 21. The pumping and injection of fuel shall begin. Then, the rotating member 4 rotates, and the fuel is pumped until the overflow port and one end of the lead-shaped groove 10 of the ring-shaped member 7 match, and the fuel is fed under pressure to the distribution port 6 and the fuel supply passage 63.
Alternatively, it is sent to the fuel injection valve from 61, 62, and 64. When the lead-shaped groove 1° and the overflow ports 71 to 74 match at position b in the developed view, the pump chamber 2 and the guide hole 3
The high-pressure fuel inside overflows to the outside (inside the pump housing, not shown) through the reed-shaped groove 10, and the injection ends. That is, during the rotation angle θ1 from position a to position b, fuel is pumped and an amount of fuel corresponding to the pumping period is injected.

Here, when the position of the ring-shaped member 7 is moved upward in the figure relative to the rotating member 4 as shown in Fig. 4-1, it was at position b in Fig. 3-2. The overflow timing changes to position C in Figure 4-2, which is a developed view of the inner peripheral surface of the ring-shaped member 7, depending on the characteristics of the diagonal lead, and therefore the pumping period increases from θ to θ2, and as a result, Naturally, the injection amount also increases. That is, by moving the position of the ring-shaped member 7 in the axial direction of the rotating member 4, it becomes possible to adjust the injection amount by overflow.

Here, the position control of the ring-shaped member 7 can be easily achieved by using known means such as a hydraulic servo or a linear solenoid actuator shown in FIG. 1-1.

[Problems to be Solved by the Invention] By the way, the above-described fuel injection amount control device developed by the inventors and pending application has the following problems. That is, it has been found that this device causes variations in the injection amount for each cylinder.

When we investigated the cause of this, we found that, like in this system, the fuel in the pump chamber 2 is pressurized and fed with the overflow ports 71 to 74 closed by the ring-shaped member 7, and the overflow ports 71 to 74 are Injection ends when 74 matches the groove 10, but in this configuration, the cam angle from the start to the end of the pressure is not specified, so even if the injection amount is adjusted to one cylinder, other cylinders may be misaligned. There was a problem with this.

To solve this problem, it is necessary to precisely machine the inclined groove 10 or the overflow ports 71 to 74, but this is impossible due to manufacturing considerations. a ring-shaped member arranged;
This problem occurs in all pumps that complete pumping of fuel by aligning the overflow port of the moving member with the low pressure port of the ring-shaped member.

For example, in the case of the pump developed by the present inventors, as shown in FIG. However, to explain the case where a machining error occurs in 72 to the retard side with respect to the rotation of the distribution member 4 from the normal position, and conversely to the advance side in 73, 'In the injection device of this method, The inner cam mechanism compresses the fuel in 2, and when it overcomes the nozzle opening pressure (not shown), injection starts, and the overflow ports 71 to 7
4 coincides with the lead 10 of the ring-shaped member 7, the injection ends. Here, the cam angle from the start to the end of injection is expressed by θ. (θ and the injection amount have a 1:1 correlation) By the way, the lead 1o of the ring-shaped member 7
is always stationary at the same position when the injection amount is constant,
Furthermore, the cam angle at which injection is started is always the same phase for all cylinders because the pumping mechanism is unique and common to all cylinders. Therefore, if the overflow ports 72 and 73 are shifted to the retard side or the advance side as described above, the angle at which the port 72 meets the lead is delayed, and the port 73
matches the lead earlier than normal. Since the phases at the start of injection are all the same, in the cylinder corresponding to port 72 where overflow is delayed, each cam θ from the start to the end of injection is
2 is large, and conversely, each cam θ3 becomes small in the corresponding cylinder of the port 73 where the overflow is early. θ is the injection amount of each cylinder and 1
Since there is a one-to-one relationship, the injection amount is large in the cylinder corresponding to the port 72, and the injection amount is small in the cylinder corresponding to the port 73, resulting in an uneven amount between the cylinders.

By the way, it is impossible to reduce the machining error to O in this type of port machining.1. Discrepancies in injection amount cannot be avoided.

Therefore, in the present invention, the cam angle θ from the start to the end of pumping is
By setting the amount in advance, it is possible to prevent deviations in the injection amount due to manufacturing errors.

[Means for solving problems]

A fuel injection pump that pressurizes and pumps fuel in a pump chamber, comprising a moving member that is driven by an engine to perform periodic motion, and a ring-shaped member disposed around the outer periphery of the moving member, An overflow port communicating with the pump chamber is opened on the outer peripheral surface of the member, and a low pressure port communicating with the low pressure side is opened on the inner peripheral surface of the ring-shaped member, and this low pressure port is connected to the moving member. During the movement stroke, the overflow port communicates with the low pressure port, and one of the overflow port and the low pressure port is formed as an inclined groove for adjusting the injection amount. In a pump in which the high pressure in the pump chamber overflows to the low pressure side and pressure feeding of fuel ends, the member in which the inclined groove is formed has the ring-shaped groove, regardless of the relative distance between the overflow port and the low pressure port. A fuel injection amount device characterized in that a straight groove is formed in which the member closes the overflow port to define a timing for starting pumping of pressurized fuel in the pressure chamber.

[Action and effect]

According to the above configuration, the cam angle θ from the start to the end of pumping can be set in advance using the straight groove, that is, the area in which the cam is used can be specified in advance, reducing variations in injection amount due to manufacturing errors. In addition, in the case of a multi-cylinder pump, it is possible to reduce the variation in the injection amount for each cylinder, and the adjustment becomes easy.

〔Example〕

The structure and operation of the present invention will be explained below according to the embodiments of the present invention shown in FIGS. 6-1 to 7. In the fuel injection amount device which has been developed by the inventors and is currently under application, the improvement according to the present invention is the shape of the reed-shaped groove provided on the inner diameter side of the ring-shaped member 7. In the present invention, as shown in the perspective view of the ring-shaped member 7 in Fig. 6-1 and the developed diagram 6-2 showing the inner peripheral surface of the ring-shaped member 7 in Fig. 6-2, the injection is caused by overflow. In addition to the diagonal lead 100 for determining the end time, a new lead 101 for determining the start of injection is preferably provided straight in equilibrium with the generatrix of the ring member (7). As the fuel distribution rotating member 4 rotates, the reeds 101 open the overflow ports 71 to 7 of each cylinder.
4 is provided on the side that meets the lead 100 earlier than the lead 100 so as to coincide with the port at exactly the phase when the fuel in the pump chamber 2 begins to be compressed.

With the above configuration, the cam mechanism allows the pressure-feeding plunger 2 to
1.・Even if 22 enters the pressure feeding process, the overflow ports 71 to 7
Since one of the leads 101 matches the lead 101, the fuel in the pump chamber 2 leaks to a low pressure and the pressure does not rise. Figure 7 shows the overflow port 71 (or 72, 73, 74) in Figure 6-2.
), the overlapping position of the fuel distribution rotating member 4 as a moving member rotates, and when one of the ports 71 to 74 comes off from the lead 101 at position e in FIG. The fuel pressure in the pump chamber 2 increases,
Pressure delivery of fuel begins and injection develops.

Then, the fuel distribution rotating member 4 further rotates, and the ports 71 to
At position f, where one of the reeds 74 coincides with the lead 100, high-pressure fuel overflows, the fuel pressure decreases, and injection ends. According to this configuration, even if the mutual angles of the four overflow ports 71 to 74 are slightly uneven, the cam angle θ from the start to the end of pumping corresponding to the injection amount is always constant, and the injection amount There is no difference between cylinders.

Note that the injection amount is controlled by changing the axial position of the ring-shaped member 7, as shown by the arrow shown in FIG. Of course, it can be realized by changing it.

As explained in detail above, in this embodiment, in addition to the diagonal lead lOO for overflow control, the straight lead 101 for determining the injection start is added, but there is a slight port machining error and the injection amount is Since deviation can be prevented and there is no variation in the injection amount between cylinders, there is an excellent effect that there is no reduction in engine output or generation of black smoke.

In addition, in this embodiment, the lead lO that determines the start of injection is
1 is shown to be in equilibrium with the inner diameter generatrix of the ring-shaped member 7, but this is because the injection start timing does not change even if the ring-shaped member 7 is moved in the axial direction. Even if it is not straight, the problem of unevenness, which is the object of the present invention, can be achieved.

Although this embodiment shows an example of an inner cam type pump, it can be applied as long as it does not deviate from the scope of the present invention. Needless to say, any fuel injection device having a ring-shaped member can be applied regardless of whether it is a distribution type or a size type.

[Brief explanation of drawings]

Fig. 1-1 is a cross-sectional configuration diagram along the central axis of the inner cam type pump developed by the inventors, and Fig. 1-2 is
AA cross-sectional view of Figure 1, 1st. -Figure 3 is B- of Figure 1-1
B sectional view, Figure 1-4 is a schematic perspective view that clearly shows the main parts of Figure 11, Figure 2-1 is C-C in Figure 1-1.
A sectional view, FIG. 2-2 is a developed view showing the inner circumferential surface of the ring-shaped member 7, and FIGS. 3 to 5 are explanations of the operation. Fig. 6-1 is a cross-sectional perspective view of the ring-shaped member 7 that constitutes the main part of the present invention, Fig. 6-2 is a developed view showing the inner peripheral surface of the ring-shaped member 7, and Fig. 7 is an explanatory diagram of the operation. It is. 4...Fuel distribution rotating member (motion member), 7...Ring-shaped member, 71, 72.73, 74...Overflow port. 100... Diagonal lead for determining injection end time, 101... Lead for determining injection start.

Claims (1)

[Scope of Claims] A fuel injection pump that pressurizes and pumps fuel in a pump chamber, comprising: an interlocking member that is driven by an engine and moves periodically; and a ring-shaped member disposed around the outer circumference of the moving member. An overflow port communicating with the pump chamber is opened on the outer peripheral surface of the moving member, and a low pressure port communicating with the low pressure side is opened on the inner peripheral surface of the ring-shaped member, and the low pressure The port communicates with the overflow port during the movement stroke of the moving member, one of the overflow port and the low pressure port is formed as an inclined groove for adjusting the injection amount, and the overflow port and the low pressure port communicate with each other. In the pump in which the high pressure in the pump chamber overflows to the low pressure side and the pumping of fuel ends when Regardless, the fuel injection device is characterized in that the ring-shaped member closes the overflow port, thereby forming a straight groove that defines the timing for starting pumping of the pressurized fuel in the pressure chamber.