JPH0231554Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an injection timing control device for a fuel injection pump.

[Conventional technology]

Among internal combustion engines, especially diesel engines, the fuel injection timing is delayed during normal operating conditions to prevent diesel knock phenomenon and to prevent exhaust gas, but when the engine temperature is low, such as when starting the engine, Since there is a risk of a misfire, the fuel injection timing is advanced. However, in conventional fuel injection timing control, as disclosed in, for example, Japanese Utility Model Application Publication No. 54-34817, only engine temperature, that is, engine cooling water temperature, is used as a control factor. No significant misfire prevention effect has been achieved. In other words _, the required advance angle characteristic depends not only on the cooling water temperature but _also on the outside air temperature as shown in _FIG . As shown in the figure, the angle is advanced to α _a , and the angle is advanced more than necessary, which increases noise and increases NO _x . On the other hand, if the cooling water temperature is t ₁ and the outside temperature is T ₂ , the advance angle will be α _b ,
The amount of advance angle is small and a large amount of white smoke will be generated.

[The problem that the idea attempts to solve]

The present invention was developed in view of these circumstances, and compared to control based only on cooling water temperature,
As shown in , when the outside temperature is T ₁ and the cooling water temperature is t ₂ , the amount of advance is less than α _a , and when the cooling water temperature is _{t 1 and} the outside temperature is T ₂
By bringing the advance angle closer to the required advance characteristic, such as α _B being larger than α _B , misfires at low temperatures can be reliably prevented, and the engine can be operated in the desired state. An object of the present invention is to provide an injection timing control device for a fuel injection pump.

[Means to solve the problem]

In order to achieve this object, an injection timing control device for a fuel injection pump according to the present invention includes an advance angle control mechanism that changes the injection timing of the fuel injection pump, an actuator that operates the advance angle control mechanism, and an engine temperature control device. an engine temperature detection device that detects the
An outside air temperature detection device detects outside air temperature, and when the outside air temperature detected by the outside air temperature detection device is below a predetermined temperature and when the engine is started, including the initial warm-up period, the outside air temperature is detected regardless of the engine speed. a first injection timing setting means for controlling the amount of movement of the actuator in the advance direction based on temperature, and normal engine operation when the outside air temperature detected by the outside air temperature detection device is below a predetermined temperature; when the engine speed increases, the second injection timing setting means controls the operation of the advance angle control mechanism in the advance direction as the engine speed increases, and the control corrects the advance amount by the first injection timing setting means. an actuator control device that corrects the actuating amount of the actuator in an advance direction to a retard direction as the engine temperature increases based on the engine temperature detected by the engine temperature detection device; means for stopping control of the advance angle control mechanism in the advance angle direction by the first injection timing setting means when the temperature reaches a predetermined temperature or higher.

In other words, the present invention is based on the fact that the outside air temperature, that is, the engine intake air temperature, has a large effect on the occurrence of misfires as well as the engine temperature, and that the outside air temperature is approximately equal to or lower than the engine temperature in the early stages of engine warm-up. This is based on the recognition that the injection timing of the fuel injection pump is controlled to advance according to the outside air temperature and cooling water temperature to prevent the generation of white smoke due to insufficient advance, and also to prevent diesel engine failure due to overadvance. This prevents this from occurring and allows the engine to operate in an overall desirable state.

〔Example〕

Hereinafter, an injection timing control device for a fuel injection pump according to a preferred embodiment of the present invention will be described with reference to the accompanying drawings.

1 and 2 are a schematic external view of a fuel injection pump incorporating an injection timing control device according to a first embodiment of the present invention, and a partially sectional front view thereof.

1 and 2, reference numeral 1 indicates an injection timing control device, and reference numeral 2 indicates a fuel injection pump in which this injection timing control device 1 is incorporated. As shown in FIG. 2, this fuel injection pump 2 includes a cam disk (not shown) that rotates together with a plunger (not shown) that pumps fuel, and a cam disk that comes into contact with the cam surface of the cam disk. and a roller member 4 held by a roller holder 3, and the plunger is rotated and reciprocated as the cam disk rotates to inject and supply fuel.

On the other hand, the injection timing control device 1 has a timer T _M , and this timer T _M is connected to the fuel injection pump case 5.
It has a timer piston 7 slidably disposed within a timer housing 6 provided therein. A portion of the fuel oil that is pressurized and supplied into the chamber of the fuel injection pump 2 by a feed pump driven in proportion to the engine rotational speed is supplied to the piston 7.
An orifice 9 is formed to introduce the pressure chamber 8 within the housing 6 . This pressure chamber 8 of the piston 7
On the opposite side, a spring 10 is disposed that biases the piston 7 in a direction against the pressure of the fuel oil introduced into the pressure chamber 8. Piston 7 has
A pin 11 is pivotally mounted at one end thereof, and the other end of this pin 11 is attached to the roller holder 3 of the fuel injection pump 2.

An injection timing control device 1 is operatively connected to a roller holder 3 of a fuel injection pump 2, and is configured to control the timer T _M
Lever 1 for controlling injection timing separately from
It has 2. When the lever 12 is moved in the direction of arrow A, the injection timing is advanced. This lever 12 is biased in the direction opposite to the direction of arrow A by a spring 13, and movement of this lever 12 in the direction opposite to the direction of arrow A is restricted by a stopper 14. .

Actuator 15 for controlling lever 12
A diaphragm actuator as shown in FIG. 3 is used. The actuator 15 has a diaphragm 17 arranged within a case 16 and connected to the lever 12 by a rod 18. The diaphragm 17 is
The inside of the case 16 is divided into an atmospheric chamber 16a and a negative pressure chamber 16b, and a spring 19 is arranged in the negative pressure chamber 16b to push the diaphragm 17 and thus the rod 18 to the left in the figure. Negative pressure chamber 16b
is connected to a vacuum pump P by a vacuum passage 20. The passage 20 is provided with an electromagnetic valve 21 that is operated according to the engine temperature, that is, the cooling water temperature, and the electromagnetic valve 21 is in an excited state when it is in the negative pressure chamber 16b.
is connected to the vacuum pump P, and the negative pressure chamber 16 is opened in a demagnetized state.
b is exposed to the atmosphere.

A cup-shaped case 22 is attached to the right side of the case 16 in the drawing. A first cylinder 23 extending in the direction of the rod 18 is disposed on the outside of the bottom wall 22a of the cup-shaped case 22. Inside this cylinder 23, a piston 2
4 is slidably fitted, and this piston 2
4 on the lever 12 side (hereinafter, the lever 12 side will be referred to as the front side and the opposite side will be referred to as the rear side), the piston 24 passes through a chamber in the case 22, and the negative pressure of the case 16 is A piston rod 25 is provided which extends into the chamber 16b. A thermally expandable wax W ₁ is housed on the rear side of the piston 24 of the cylinder 23, and the cylinder 23
A fin 23a is provided on the outer periphery of the wax W 3 to efficiently transmit outside temperature to the wax W ₁ .

Inside the case 22, a second cylinder 26 coaxial with the piston rod 25 is provided integrally with the piston rod 25, as shown in FIG. This cylinder 26 has an annular space 26a with a small diameter inside.
An annular space 26b with a large diameter is formed. A piston 27 is slidably fitted in the space 26a, and a front wall of the piston 27 is provided with a passage from the piston 27 to the negative pressure chamber 16 of the case 16.
A piston rod 28 is provided which extends to b. This rod 28 has a space 28a extending in the axial direction formed therein.
5 is of a nested type, and the tip of the rod 28 extends at least to the tip of the rod 25 when the rod 28 is fully retracted. A thermally expandable wax _W2 is housed in the space 26a on the rear side of the piston 27.
A cooling water supply pipe 29a and a cooling water discharge pipe 29b are connected to the space 26b, and the cooling water Wa is circulated therein.

Next, the operation of the injection timing control device 1 for the fuel injection pump 2 having the structure explained above will be explained.

In the normal operating state of the engine, the piston 7 moves against the spring 10 by the fuel oil supplied into the pressure chamber 8 from the feed pump, and this movement is caused by the pin 11 to move the piston 7 to the roller holder 3.
The advance angle is controlled according to the engine speed. Note that in the normal operating state of this engine, the solenoid valve 21 communicates the negative pressure chamber 16b of the actuator 15 with the atmosphere.
This actuator does not operate, and therefore no advance angle control is performed by this actuator.

Next, advance angle control when starting the engine in a cold state will be explained.

For example, when the engine is stopped, the engine temperature is at the cooling water temperature t _c (see Figure 8B), which is approximately 15°C or lower, and is below a predetermined value of the engine temperature, which is set to 30°C, for example, which requires low-temperature start control. temperature, and the outside temperature is below 15℃ (No. 8
(see Figure B), waxes W ₁ and W ₂
are both in the contracted state, and since the cylinder 26 is integrally provided with the rod 25 as described above, the rod 25 is moving to the right in the figure along with the cylinder 26, and the cylinder 26 is being moved to the right in the figure. Rod 28 of 26 has also moved to the right, and both rods 25 and 28 are in the retracted position shown in FIG. When the engine is started under the above conditions, the vacuum pump P is simultaneously driven, and since the engine cooling water temperature is below the predetermined temperature as described above, the solenoid valve 21 is activated in the negative pressure chamber of the actuator 15. 16b is connected to the vacuum pump P. Therefore, since the inside of the negative pressure chamber 16b becomes negative pressure,
The diaphragm 17 moves to the right against the spring 19 until it abuts the tips of the rods 25 and 28. As the diaphragm 17 moves, the rod 18 also moves to the right, and the lever 12 is rotated in the direction of arrow A by the stroke of this movement. The lever 12 rotates the roller holder 3 by this amount of rotation to perform advance angle control. By advancing the fuel injection timing as described above, as shown in FIG. 8B, the ideal advance angle α _c is set, and together with the diesel knock, misfire of the engine is prevented.

When the engine starts operating and the engine temperature rises, and the engine coolant temperature rises, the wax W ₂ in the cylinder 26 begins to expand. Then,
The piston 27 and therefore the piston rod 28 move to the left, displacing the diaphragm 17 and the rod 1.
Move 8 to the left. At this time, the lever 12 is rotated in the direction opposite to the arrow A by the action of the spring 13, and the advance angle is gradually delayed, so that when the cooling water temperature is _tH , the ideal The advance angle α _H is set to a suitable advance angle amount α H to prevent both misfire and white smoke.

Next, referring to FIG. 4, a control device 30 for the movement stroke of the diaphragm 17 of the actuator 15 used in the injection timing control device according to the second embodiment of the present invention will be described. Incidentally, since the structure of the actuator 15 is the same as that shown in FIG. 3, each member and component is given the same reference numeral as in FIG. 3, and a description thereof will be omitted.

The control device 30 has a case 31 that is disposed on the right side of the case 16 of the actuator 15 in the drawing and extends in the axial direction of the rod 18. The inside of this case 31 is divided by a partition wall 32 into a first chamber 33a and a second chamber 33b. A first cylinder device 3 is provided on the wall surface of the partition wall 32 on the first chamber 33a side.
4 are provided. This first cylinder device 3
A piston (not shown) is slidably disposed inside the cylinder 35 of No. 4, and a piston rod 36 is provided on the front surface of this piston.
This piston rod 36 extends through the partition wall 32 to the second chamber 33b. A thermally expandable wax is housed inside the cylinder 35 on the rear surface side of the piston. A cooling water supply pipe 37a and a cooling water discharge pipe 37b are connected to the first chamber 33a, and the cooling water Wa is circulated therein. As the temperature of the cooling water Wa increases, the wax within the cylinder 35 expands and extends the piston rod 36, or contracts as the temperature decreases and shortens the piston rod 36.

A second cylinder device 38 is fixed to the tip of the piston rod 36 extending into the second chamber 33b. This second cylinder device 38 is connected to the first cylinder device 38.
The structure is almost the same as that of the cylinder device 34 of
Inside the cylinder 39 is a piston (not shown).
is slidably arranged, and a piston rod 40 is provided on the front surface of this piston. This piston rod 40 is connected to the negative pressure chamber 16 of the case 16.
It extends to inside b. A thermally expandable wax is housed inside the cylinder 39 on the rear side of the piston.

An opening 41 is formed in the outer wall of the case 31 forming the second chamber 33b.
The inner cylinder device 38 is exposed to the outside air through this opening 41. As the temperature of the outside air increases, the wax within the cylinder 39 expands to extend the piston rod 40, or as the temperature decreases, the wax in the cylinder 39 contracts to shorten the piston rod.

As described above, due to the action of the first and second cylinder devices 34 and 38 arranged in series, the third
In a manner similar to the device shown in the figure, the diaphragm 1
The stroke of No. 7 is controlled, and advance angle control is thereby performed.

Next, an injection timing control device according to a third embodiment of the present invention will be described with reference to FIGS. 5 and 6.

A step motor 51 is operatively connected to the lever 12 for controlling the injection timing via a rod 50.
A control circuit 54 is connected to control the operation of the step motor based on output signals from an outside air temperature sensor 52 and an engine coolant temperature sensor 53.

This control circuit 54 is composed of a microcomputer, and performs control according to the sequence shown in FIG. 6, for example.

When the engine starts and the control circuit 54 operates, the control circuit 54 first detects the outside air temperature and outputs an outside air temperature detection signal S.
Enter(). Next, based on this detection signal S1, a required advance angle is calculated, the number of steps corresponding to the calculated required advance angle is called (), and a pulse signal P corresponding to this called number of steps is output to the step motor 51. (). The step motor 51 rotates by the number of steps corresponding to the number of pulses of the pulse signal P, rotates the lever 12 in the direction of arrow A, and advances the angle by the required amount.

Next, the coolant temperature To for canceling the cold start (CSD) control is called (), and this called coolant temperature To is divided by the number of steps called in the above step (). Let the answer be △T.
After that, the increase ΔT' in the cooling water temperature is detected (), and it is determined whether this temperature increase ΔT' is larger than the above ΔT (), and when this determination is YES, the step motor 51 Outputs a pulse signal P _R to rotate the motor by a step in the retard direction (). The steps indicated by symbols , , , are repeated until the determination in the step becomes YES, that is, until the cooling water temperature T reaches the above-mentioned To.

As described above, the advance angle is controlled according to the outside air temperature and the cooling water temperature.

In place of the step motor 51 in the above embodiment, a seventh
As shown in the figure, using a linear solenoid 60, the output S1 of the outside air temperature sensor 61 and the output S2 of the cooling water temperature sensor 62 are input to the control circuit 63, and the subtraction circuit 64 inputs (To-S1)-S2 (Here, To is the temperature at which low-temperature start control is required), and outputs a control signal S3, which is, for example, a current, from the drive circuit 65 according to the answer, and this control signal S
3 controls the solenoid 60 and lever 12.
It is also possible to control the advance angle.

[Effect of idea]

As described above, the injection timing control device for a fuel injection pump according to the present invention advances the fuel injection timing by considering not only the engine temperature, that is, the cooling water temperature, but also the outside temperature. This can be achieved even more reliably, and is particularly effective in preventing misfires at low temperatures.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a fuel injection pump incorporating an injection timing control device according to a first embodiment of the present invention, and FIG. 2 is a partially sectional front view of the fuel injection pump shown in FIG. 3 is a longitudinal sectional view showing the actuator portion of the injection timing control device shown in FIG. 1, and FIG. 4 is the actuator portion which is the main part of the injection timing control device according to the second embodiment of the present invention. FIG. 5 is a schematic diagram showing an injection timing control device according to a third embodiment of the present invention using a step motor as an actuator, and FIG. 6 is a longitudinal sectional view showing the injection timing control device shown in FIG. 7 is a flowchart showing an example of the operation of the timing control device; FIG. 7 is a schematic diagram showing an injection timing control device according to a fourth embodiment of the present invention using a linear solenoid as an actuator; FIG. FIG. B is an explanatory diagram showing the required advance angle characteristics. DESCRIPTION OF SYMBOLS 1... Fuel injection pump, 2... Injection timing control device, 12... Lever, 15... Actuator,
23, 26...Cylinder, P...Vacuum pump.

Claims (1)

[Scope of Claim for Utility Model Registration] An advance angle control mechanism that changes the injection timing of a fuel injection pump, an actuator that operates the advance angle control mechanism, an engine temperature detection device that detects engine temperature, and an outside air temperature detection device. an outside air temperature detection device that detects the outside air temperature, and when the outside air temperature detected by the outside air temperature detection device is below a predetermined temperature and when starting the engine including the initial warm-up period, the outside air temperature is determined based on the outside air temperature regardless of the engine rotation speed. a first injection timing setting means for controlling the amount of movement of the actuator in the advance direction; and when the outside air temperature detected by the outside air temperature detection device is below a predetermined temperature and the engine is in normal operation; a second injection timing setting means for controlling the operation of the advance angle control mechanism in an advance direction as the engine speed increases; and a control device for correcting the advance amount by the first injection timing setting means. , an actuator control device that corrects the actuation amount of the actuator in the advance direction to the retard direction as the engine temperature increases based on the engine temperature detected by the engine temperature detection device; and the engine temperature is equal to or higher than a predetermined temperature. When you become
An injection timing control device for a fuel injection pump, comprising means for stopping operation control of the advance angle control mechanism in an advance direction by the first injection timing setting means.