JPH02298635A - Fuel injection ratio controller for distribution type fuel injection pump - Google Patents

Abstract

PURPOSE:To control the fuel injection ratio of a diesel engine property and easily by reducing pressure at a fuel injection valve side to adjust a time until the fuel injection valve is opened, and thereby changing the starting position of use of an unequal speed cam to a target position. CONSTITUTION:A plunger M3 reciprocated in response to the movement of an unequal speed cam M2 synchronized with the rotation of a diesel engine M1 increases fuel pressure in a pressurizing chamber M4. A check valve M7 which is opened when differential pressure is more than a predetermined level is provided in a passage M6 which connects the pressurizing chamber M4 to a fuel injection valve M5. In the abovementioned device, the target position of starting of use of the unequal speed cam M2 is calculated by a means M8. Pressure on the fuel injection valve M5 side after the check valve M7 is closed is reduced. The pressure on the fuel injection valve M5 side is reduced further to adjust a time until the fuel injection valve M5 is opened, and thereby the starting position of use of the unequal speed cam M2 is changed to the target position by a means M10.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention] The present invention relates to a fuel injection rate control device for a distributed fuel injection pump that adjusts the fuel injection rate according to the operating state of a diesel engine.

[Prior Art] Conventionally, as a device for controlling fuel injection in a diesel engine, a device has been proposed that adjusts the fuel injection start timing according to changes in fuel or engine conditions (see Japanese Patent Publication No. 56-10462). has been done. In addition, in recent years (t), as a way to more precisely control fuel injection, the injection rate of fuel supplied from a distributed fuel injection pump is adjusted according to the operating state of the diesel engine, and the output and exhaust gas purification performance are adjusted. improve,
Alternatively, technologies to reduce noise have been proposed (Special Publications Act, 1986).
(See Publication No. 2-61774).

[This technology] Utilizes the timer installed in the distribution type fuel injection pump to advance or retard the inconstant velocity cam, and also controls the opening and closing of the fuel flow path on the pressurizing chamber side using a solenoid valve. This controls the fuel injection start timing and end timing. That is, by changing the usage area of the non-uniform velocity cam corresponding to the fuel injection period, the fuel injection rate corresponding to the amount of movement of the non-uniform velocity cam per unit time is changed.

[Problem to be solved by the invention] However, when trying to change the fuel injection rate using a timer as in the past, depending on the operating state of the diesel engine, it is not only necessary to control the timer, but also to change the fuel injection rate in conjunction with the timer control. Then, during fuel injection control, a solenoid valve is used to control the opening and closing of the flow path on the pressurizing chamber side, and the fuel injection start timing and fuel injection end timing must be changed. However, it is an object of the present invention to provide a fuel injection rate control device for a distribution type fuel injection pump that can suitably and easily control the fuel injection rate of a diesel engine. purpose.

1. Means for Solving the Problems Fuel injection rate control device for a distribution type fuel injection pump according to the present invention, which has been made to solve the above problems.1. t, as illustrated in FIG. 1, a plunger M3 that reciprocates according to the movement of an inconstant velocity cam M2 synchronized with the rotation of the diesel engine M1, and a pressurizing chamber M4 that increases the fuel supply pressure by the plunger M3. a flow path M6 that communicates the pressurizing chamber M4 with a fuel injection valve M5 that injects fuel at a predetermined pressure or higher; and a check valve that is disposed in the flow path M6 and opens when the differential pressure is higher than or equal to a predetermined value. In the fuel injection rate control device for a distribution type fuel injection pump, the cam determines a target position for starting use of the inconstant velocity cam M2 corresponding to a desired fuel injection rate based on the operating state of the diesel engine M1. a use position calculation means M8; a pressure reduction means M9 provided on the fuel injection valve M5 side of the flow path M6 to reduce the pressure on the fuel injection valve M5 side after the check valve M7 is closed; By driving M9 to reduce the pressure on the side of the fuel injection valve M5, the time from the start of pressurization by the plunger M3 until the opening of the fuel injection valve M5 is adjusted, and the inconstant velocity cam M2 is The gist of the present invention is to include a cam usage position changing means MIO for changing the usage start position to the target position.

[Function] The fuel injection rate control device for the distributed fuel injection pump of the present invention (
The non-uniform speed cam M is synchronized with the rotation of the diesel engine M1.
2 moves, the plunger M3 reciprocates, and the plunger M3 increases the fuel supply pressure in the pressurizing chamber M4.

When the pressure of the fuel increases and the differential pressure on both sides of the check valve 7 exceeds a predetermined value, the check valve 7 is opened and the pressurizing chamber M4 and the fuel injection valve M5 are communicated with each other. It is supplied to the valve M5 side. When the pressure of this fuel exceeds the opening pressure of fuel injection valve M5, fuel is injected from fuel injection valve M5. One breath after the fuel is injected, the check valve 7 is closed as the fuel pressure decreases.

Here, the cam use position calculating means M8 calculates a target position for starting use of the inconstant velocity cam M2 corresponding to the fuel injection rate, depending on the operating state of the diesel engine M1. Then, the cam use position changing means M10 drives the pressure reducing means M9 and adjusts the time from the start of pressurization by the plunger M3 until the opening of the fuel injection valve M5, and starts using the inconstant velocity cam M2. Change the position to the target position.

Like this 1: By changing the use start position of the inconstant velocity cam M2 when fuel is actually injected and the accompanying use area, that is, the moving speed of the inconstant velocity cam M2 in the axial direction (cam The fuel injection rate is changed by using different regions of the fuel injection rate (speed).

Next, the present invention will be explained in detail, but in order to make the explanation clearer, the present invention will be explained based on an embodiment based on FIG.

FIG. 2 is a graph showing an example of the relationship between the change in cam lift (cam profile) of the inconstant velocity cam M2 with respect to the cam angle, and the cam speed with respect to the cam angle. As is clear from the figure, the cam lift amount increases as the cam angle increases, but since the cam used is a non-uniform velocity cam M2 with an uneven cam profile, the cam speed at each cam angle also changes. That is, the cam speed changes depending on the range of use of the non-uniform speed cam M2.

Here, as a means for reducing the pressure on the fuel injection valve M5 side, consider a configuration in which, for example, fuel is returned from the fuel injection valve M5 side to a low pressure side such as the pressurizing chamber M4 side to reduce the pressure. In this case, Table 1 shows the time from the start of fuel pressurization until the check valve M7 is opened and the opening pressure of the fuel injection valve M5 is reached.
It changes depending on the reduced pressure. That is, the fuel injection start timing changes according to this pressure, and as a result, the usage range of the inconstant velocity cam M2 when fuel is actually injected changes. Example I;! , the returned fuel amount (sucked back amount) is X, Y, Z (X(Y(Z)),
In the example shown in FIG. 2, the cam speed usage area 1 corresponds to each time. t, respectively change to XT, YT, and ZT.

In this way, the suction amount changes the use start position of the inconstant velocity cam M2 when fuel is actually injected and the associated use area, so the cam speed changes.Thereby, the fuel injection rate changes. adjusted. The above-mentioned configuration and graph 1 are merely given as an example of the present invention, and the pressure can be reduced by removing fuel from the fuel injection valve M5 side, changing the volume of the flow path on the fuel injection valve M5 side, etc. Of course, various configurations can be adopted.

[Example] Next, a preferred example of the present invention will be described in detail based on the drawings. FIG. 3 shows a system configuration of a fuel injection rate control device for a distribution type fuel injection pump, which is an embodiment of the present invention.

As shown in the figure 1: Fuel injection rate control device 11. t. A distribution type fuel injection pump that pressurizes and pumps the fuel to be supplied to the diesel engine 2.3. It is comprised of an electronic control unit (hereinafter simply referred to as ECU) 7 that drives and controls the fuel injection pump 3 according to the operating state of the diesel engine 2.

The diesel engine 2 has a cylinder 11, a combustion chamber 14 is formed from a piston 12 and a cylinder head 13. A fuel injection valve 15 is disposed in the combustion chamber 14.

The driving force of the diesel engine 2 is transmitted through the distribution type fuel injection pump 31 & the drive pulley 21. The drive shaft 2 coupled to the drive pulley 21
2 (top) Vane type pump 2 which is a fuel feed pump
3. A pulse gear 24 and a coupling 25 having a plurality of protrusions carved at equal intervals on the outer peripheral surface are connected. Coupling 25 (connected to one end of plunger 27 integrally coupled with front cam plate 26) The other end of plunger 27 is fitted inside cylinder 28. Plunger 27 (front) It is supported so as to be reciprocally movable and is urged in the direction of arrow B by a spring 29. It rotates integrally with the coupling 25.

An upper roller ring 30 is disposed between the coupling 25 and the cam plate 26.
A cam roller 31 is attached to the surface facing the cam plate 26 of FIG. On the other hand, on the surface of the cam plate 26 facing the roller ring 3o (upper cam plate 2
A convex cam portion 32 that determines the movement of the cam plate 26 and the cam portion 32 protrudes.
is formed.

At the head 41 of the housing 40 of the fuel injection pump 3 (
Pressurized chamber 42 by plunger 27 and cylinder 28
is formed. The plunger 27 is a member that rotates and slides within the cylinder 28 to pressurize the fuel.
Fuel introduction recess 43 that sucks fuel inside the housing 40
．． Distribution boat 44 for distributing pressurized fuel. It is equipped with spill boats 4 and 5 that send surplus fuel out of the pressurized fuel to the ocean. Further, this plunger 27 has a spill ring 46 that adjusts the end timing of fuel pressurization and controls the fuel injection amount, and is fitted in the vicinity of the spill port 45 and is slid by a governor mechanism. There is.

Further, a fuel introduction passage 4 is provided in the head 41 of the housing 40 (Table 1), which communicates the inside of the housing 40 with the pressurizing chamber 42.
A fuel cut solenoid 48 for cutting off the introduction of fuel is arranged in this fuel introduction passage 47. Also, a plunger 27 communicating with the pressurizing chamber 42
A fuel supply passage 50 that supplies fuel to the fuel injection valve 15 side is open to the distribution port 44 of the fuel injection valve 15.A delivery valve 5, which is a check valve that opens and closes the passage, is connected to the fuel supply passage 50. A fuel vibrator 52 that supplies fuel to the fuel injection valve 15 is connected to the downstream side of the delivery valve 51 .

As shown in FIG. 4, the valve body 51 of the delivery valve 51
al & sliding according to the fuel pressure on the fuel supply passage 50 side,
It is normally biased in the direction of arrow B by a spring 54. In the vicinity of this delivery valve 51, a valve body 51a is provided.
A side flow path 60 is provided to bypass the fuel supply passage 50 and the fuel vibrator 52 side. This side flow path 60 is provided with a solenoid valve 62 that opens and closes the flow path.A pressure sensor 64 is provided on the upstream side of the solenoid valve 62, and a pressure sensor 66 and a pressure sensor 68 are provided on the downstream side of the solenoid valve 62.

In addition, as shown in FIG.
A flyweight 70 that rotates depending on the operating state of the diesel engine 2. A governor 72 that moves the spill ring 46 using the flyweight 70, and a control lever 74 that adjusts the movement of the spill ring 46 in conjunction with the accelerator pedal. A governor spring 76, a tension lever 78, etc. are provided. Furthermore, the housing 40
A timer 80 is provided which moves the roller ring 30 to change the timing of fuel injection.

In this figure, the timer 80 and the vane pump 23 are shown unfolded at 90 degrees.

Table 1: The above-described fuel injection rate control device 11 includes the pressure sensors 64 and 66 as detectors.

Reference signal generation sensor 8 detects the fuel injection stroke of each cylinder of the diesel engine 2 from the rotation of the drive pulley 21
1. The drive shaft 22 is closely opposed to the pulse gear 24.
A rotational speed sensor 82. detects the rotational speed Ne of the diesel engine 2 from the rotational speed of the diesel engine 2. An ice temperature sensor 83 for detecting the temperature of the cooling water of the diesel engine 2 is provided.

In addition, the ECU 7 includes the well-known CPU 7a, ROM 7b,
It is configured as a logic operation circuit centering around RAM 7c and timer 7d.The input/output section 7 is connected via the common bus 7e.
It is connected to f and performs input/output with the outside. The detection signals of each sensor and switch mentioned above are sent to the CPU via the input/output section 7f.
On the other hand, cpU7a is input/output blade part 7ft.
2, a control signal is output to the solenoid valve 62, etc.

Next, a fuel injection rate control process executed by the ECU 7
That is, the process of driving and controlling the electromagnetic valve 62 will be explained based on the flowchart shown in FIG.

Control of the present embodiment + By controlling the opening and closing of the electromagnetic valve 62 provided in the i side flow path 60, the above-mentioned sucking back amount is changed and the start timing of fuel injection is adjusted, thereby making it possible to use the inconstant velocity cam 34. The fuel injection rate is controlled by changing the area.

First, in step 100, the fluctuation (pressure waveform) of the fuel pressure on the fuel injection valve 15 side is measured by the pressure sensor 6 on the fuel injection valve 15 side.
The process of reading from the output of step 6 is performed. Next step 1
In step 10 (above step), a process of converting the pressure waveform read in step 00 into an injection period TC is performed.Continued (in step 120, the injection period TC calculated in one table is evaluated in advance on the bench according to the operating state). A comparison process is performed with the determined optimal map value (period) TM.

In this step 120, the injection period TC calculated above is
If it is determined that the period is shorter than the optimum period TM of the map, this indicates a condition in which a large amount of fuel is injected in a short period of time, that is, a condition in which the fuel injection rate is too large than the optimum value. Therefore, step 130 , a process is performed to shorten the opening time t of the solenoid valve 62 so as to reduce the amount of sucking back.If this amount of sucking back is small, the fuel pressure on the fuel injection valve 15 side is maintained at a relatively high state. After the fuel is raised in the pressurizing chamber 42, it reaches the opening pressure of the fuel injection valve 15 in a short time.As a result, the timing of injecting the fuel becomes earlier, and as a result, as shown in FIG. Since the range of use of the non-uniform velocity cam 34 is changed to the range xT where the cam speed is smooth, the fuel injection rate is reduced.

Note that the engine rotational speed N also changes before and after the solenoid valve 62 opens.
e. Fuel injection amount Since the fuel pressure fluctuates depending on the accelerator opening, etc.
, 66 is determined by the time integral of the differential pressure. In addition, simply advancing the start time of fuel injection will increase the fuel injection amount (Table 1), so the end time of fuel injection must also be adjusted (by testing, etc., the governor should be Set the characteristics.

On the other hand, in step 130, if the calculated injection period TC is longer than the optimum period TM of the map (contrary to the above, the fuel injection rate is considered to be too small, so in step 40), the solenoid valve The opening time t of the valve 62 is lengthened to increase the amount of suction back.As a result, the timing of fuel injection is delayed, and the range in which the inconstant velocity cam 34 is used is changed to the range ZT (Figure 2) where the cam speed is large. to increase the fuel injection rate.

Further, in step 130, if the calculated injection period TC is equal to the optimum period TM of the map (since the fuel injection rate is considered to be appropriate, the opening time t of the solenoid valve 62 is
This process is temporarily terminated without making any changes.

Next, the solenoid valve 62 that is driven by the control described above and the valve body 51 of the delivery valve 51 that operates in conjunction with the solenoid valve 62
The operations of a and the like will be explained in more detail together with the above control.

First, as the drive shaft 22 rotates, the inconstant speed cam 34 rotates, and the cam portion 32 rides on the cam roller 31, so that the plunger 27 moves in the six directions of the arrow while performing rotational movement.

As a result, the fuel introduced into the pressurizing chamber 42 from the fuel introduction passage 47 is pressurized. The pressurized fuel is supplied to the fuel supply passage 501 via the distribution port 44.

Due to the above pressurization, the fuel pressure on the fuel supply passage 50 side increases, and when the difference in pressure on both sides of the valve body 5+a becomes equal to or more than a predetermined value,
The valve body 51a moves in the direction of arrow A against the biasing force of the spring 54 to open the fuel flow path.
2 side (fuel injection valve 15 side). As a result, the fuel pressure on the fuel injection valve 15 side increases.

Subsequently, the plunger 27 moves in the direction of arrow A, and when the fuel pressure further increases and reaches the opening pressure of the fuel injection valve 15,
Fuel is injected into the cylinder 14 from the fuel injection valve 15.

2. Next, when the plunger 27 moves in the six directions of the arrow, the spill boat 45 reaches the end of the spill ring 46, the fuel overflows from the spill boat 45 into the housing 40, and the fuel pressure drops at once.

This decrease in fuel pressure closes the fuel injection valve 15, so fuel injection ends. In other words, the end timing of fuel injection is determined by the position of the spill ring 46, so the amount of fuel injection is adjusted.

Then, when the fuel pressure decreases, the valve body 51a is moved by the spring 54.
It moves in the direction of arrow B due to the urging force of , and the fuel supply passage 50 is blocked. After the cutoff, the fuel pressure on the fuel supply passage 50 side becomes lower than the fuel pressure on the fuel injection valve 15 side because the flow passage on the fuel supply passage 50 side communicates with the inside of the housing 40 and the plunger 27 also begins to move in the direction of arrow B. will also be lower.

Here, the judgment in step 120 of the control described above is performed, and the processing in step 130 or step 140 is performed.
That is, the actual fuel injection period TC is compared with the optimum period TM stored in the map, and the opening time t of the electromagnetic valve 62 of the side flow path 60 is controlled according to the comparison result. Note that when this solenoid valve 62 is opened, fuel is returned from the fuel injection valve 15 side to the fuel supply passage 50 side due to the difference in fuel pressure, but since the amount of fuel sucked back varies depending on fuel pressure, etc. The amount of sucking back is calculated based on the outputs from the positive force sensors 64 and 66, and the opening time t of the solenoid valve 62 is controlled.

This allows the pressure on the fuel injection valve 15 side to be set arbitrarily.

Next, when the plunger 27 moves in the direction of the arrow again to pressurize the fuel, the fuel supply passage 50 side and the fuel injection valve 1
According to the pressure on the 5 side, the valve body 51'a moves to open the flow path. For example, if the pressure on the fuel injection valve 15 side is higher than the previously set pressure, the opening pressure of the fuel injection valve 15 will be reached more quickly than last time, so the fuel injection start time will be earlier than last time. . As a result, the range in which the non-uniform velocity cam 34 is used when fuel is actually injected is changed to a range in which the cam speed is more moderate, resulting in a reduction in the fuel injection rate.

On the other hand, contrary to the above, 1: If the pressure on the fuel injection valve 15 side is lower than the previous pressure, the fuel injection valve 15
Since the valve opening pressure reaches , the start timing of fuel injection will be later than the previous time. As a result, the range in which the inconstant velocity cam 34 is used when fuel is actually injected is changed to a range in which the cam speed is higher, so that the fuel injection rate increases.
゛As explained above, according to this embodiment, by adjusting the opening time t of the solenoid valve 62 of the 1'L side flow path 60, the amount of fuel sucked back is adjusted, and the fuel injection rate is suitably controlled. be able to. Thereby, it becomes possible to improve output and purification of exhaust gas, and to effectively reduce noise. Moreover, this control (complex control in conjunction with the mountain timer 80) is not necessary, so it is simple, and furthermore, since a piezoelectric actuator or the like is not required as a means for adjusting the fuel pressure, the structure is simplified.

In this embodiment, the fuel injection rate was precisely controlled by using the suction back, but for example, the pressure sensor 66 on the fuel injection valve 15 side was used to detect the fuel pressure, and the detected fuel pressure reached a predetermined value. The solenoid valve 62 may be controlled so as to achieve this.

Furthermore, instead of driving the spill ring 46 by setting the governor characteristics in advance, an electromagnetic spill valve may be used to control the timing of fuel injection and the end timing of fuel injection according to the fuel injection amount.

1 animal 2 left 1 As described in detail above, the fuel injection rate control device for the distribution type fuel injection pump of the present invention changes the pressure based on the pressure on the fuel injection valve side detected by the pressure sensor and the operating state of the diesel engine. The pressure is adjusted by controlling the means.

By adjusting the pressure, it is possible to change the use start position of the inconstant velocity cam corresponding to the fuel injection start timing, and the fuel injection rate can be easily controlled. Therefore, the diesel engine can be suitably operated according to various operating conditions, and the output and exhaust gas purification performance can be improved, and noise can also be reduced. Furthermore, since the fuel injection rate can be changed with a simple configuration, the control device can be manufactured easily.

[Brief explanation of the drawing]

Fig. 1 is a basic configuration diagram conceptually illustrating the contents of the present invention. Fig. 2 is a graph explaining the operating principle of an inconstant velocity cam. Fig. 3 is a system configuration diagram showing an embodiment of the present invention. FIG. 4 is a cross-sectional diagram showing the vicinity of the side channel. FIG. 5 is a flowchart showing the control of this embodiment. Ml...Diesel engine M2...Inconstant speed cam M3...Plunger M4...Pressure chamber M5...Fuel injection valve M6...Flow path Ml...Check valve M8... Cam use position calculating means M9...pressure reduction means Mlo...cam use position changing means 1...fuel injection rate control device 2...diesel engine 3...distribution type fuel injection pump 7...electronic Control unit (ECU) 15...Fuel injection valve

Claims (1)

[Scope of Claims] 1. A plunger that reciprocates according to the movement of an inconstant velocity cam synchronized with the rotation of a diesel engine, a pressurizing chamber that increases the fuel supply pressure by the plunger, and a pressurizing chamber that injects fuel at a predetermined pressure or higher. A fuel injection rate of a distribution type fuel injection pump comprising a flow path that communicates the pressurizing chamber with a fuel injection valve that performs fuel injection, and a check valve that is disposed in the flow path and opens when the differential pressure is equal to or higher than a predetermined value. The control device includes a cam use position calculation means for calculating a target position for starting use of the inconstant velocity cam corresponding to a desired fuel injection rate based on the operating state of the diesel engine, and a cam use position calculation means on the fuel injection valve side of the flow path. A pressure reducing means is provided to reduce the pressure on the fuel injection valve side after the check valve closes, and the pressurization by the plunger is reduced by driving the pressure reducing means to reduce the pressure on the fuel injection valve side. cam use position changing means for changing the use start position of the inconstant velocity cam to the target position by adjusting the time from when the inconstant velocity cam is started until the fuel injection valve opens. Fuel injection rate control device for distribution type fuel injection pump.