JPS58104332A - Fuel jet pump for internal combustion engine - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel injection pump for an internal combustion engine. In this case, the fuel injection pump is equipped with an adjusting piston that is operated against a return force by the liquid from the feed pump that is pumped in proportion to the rotational speed in order to adjust the injection start time, and the pressure of the liquid is adjusted. A control mechanism is provided for proportional control of the rotational speed via a pressure control valve, said pressure control valve being movable between the pressure chamber and the return spring chamber against a return force and controlling the outflow cross-sectional area. a pressure valve having a movable wall for controlling and operating in conjunction with at least one operating characteristic value, such as engine temperature, and at least one valve spring to additionally influence said fluid pressure; Concerning the format that is provided. A type of fuel injection pump is already known in which the pressure proportional to the rotational speed, which changes the injection start timing, is variable by a single valve that operates in relation to temperature. According to this, for example, during a cold start and at high speeds after a cold start, the injection start timing is shifted earlier to leave sufficient time for fuel metering and a correspondingly good ignition or combustion to occur. - In this case the ambient water temperature or the cooling water temperature is taken into account.

However, even after a very short running time, sufficient heating already occurs in the cylinders of the engine, so that in the case of the known example, the restoration of the earlier injection start time is delayed even further. Moreover, early adjustment of the injection start time results in significant combustion noise, which remains unnecessarily long in the case of injection start adjustment that is mostly temperature-related.

According to the fuel injection pump of the present invention having the structure shown in claim 1, the following advantages can be obtained. That is, in simple form, in addition to the temperature-related influences on the injection timing adjustment at engine start-up and high engine speeds, there is an additional speed-related influence, and this additional influence By force, the injection start timing adjustment can be reversed from a predetermined pump rotational speed.

The invention will now be explained with reference to the exemplary embodiment shown in the drawings: An adjusting piston 3 engages via a pin 2 in a cam arrangement of a fuel injection pump 1 for adjusting the injection start timing. The adjusting piston 3 can be displaced against the return spring 5 by the pressure fluid in the working chamber 4; in this case, the more it is displaced in the direction of the return spring 5, the closer the injection start time is to the top dead center of the piston of the engine. However, it is shifted early. A feed pump 6, which supplies fuel proportionally to the rotational speed, sucks fuel from the fuel tank 7 and supplies it via a discharge conduit 11 to the suction chamber 8 of the injection pump 1.
supply to Fuel is supplied from this suction chamber 8 to the original fuel injection pump main body (not shown). The suction chamber 8 is connected to the working chamber 4 via a bore 9 in the adjusting piston 3 .

A control conduit 12 branches off from the discharge conduit 11 of the feed pump 6 and leads to a pressure chamber 13 of a pressure control valve 14 .

The pressure control valve 14 controls the fuel pressure prevailing upstream of the feed pump 6, in particular the pressure in the suction chamber 8, in relation to the rotational speed, and in this case, as the rotational speed increases, the pressure difference increases proportionally. and increases. This rotational speed-related pressure also prevails in the working chamber 4, so that the adjusting piston 3 is shifted forward as the rotational speed increases and thus the pressure increases. The pressure control valve 14 is closed by a piston 15 which serves as a movable wall. The piston 15 is movable against the control spring 16 to limit the pressure chamber 13 and to open the outlet 17 to a greater or lesser degree, through which the fuel can flow back into the return conduit 1.
8 and then back to the fuel tank 7 or the suction side of the feed Ponzoro. A return spring chamber 19 accommodating the control spring 16 is formed on the opposite side of the piston 15 from the pressure chamber 13 , and a restricting hole 20 in the piston 15 closes the pressure chamber 1 .
3 is connected.

As is well known, fuel injection in a diesel engine takes place when the engine piston is within its top dead center. The injection start point can be from just before to just after top dead center depending on the rotational speed and the injection amount, and is generally earlier for high rotational speeds than for low rotational speeds. During the time that fuel is required for the distance between the fuel injection pump and the nozzle,
The angular velocity of the engine crankshaft changes in accordance with the rotational speed during the required time, which is related to the rotational speed of the knob and is approximately constant. Such changes in the time relationship are compensated for by the injection timing adjustment device. The ignition delay in known continuous diesel engines is related to the temperature of the fuel and the temperature of the air compressed within the cylinder. To compensate for this ignition delay, it is advantageous to advance the injection start timing if the engine is running cold. Well-known notice,
In order to bring the internal combustion engine up to high speed quickly, it is advantageous to carry out the adjustment early at the time of starting. Another feature of a cold internal combustion engine is that when injection starts early, the exhaust gas has a less bluish tinge than when it starts later.

For warm-up of the internal combustion engine, it is advantageous if the fuel pressure in the suction chamber 8 and thus in the working chamber 4 is relatively high, so that an additional temporary early adjustment of the injection start timing is possible. can get. However, this increase in fuel pressure requires reducing the outflow cross-sectional area at the outflow port 17 of the fuel return sump. In the case of the invention, one pressure valve is configured as a pressure holding valve 22 in series with the pressure control valve 14 in order to influence the fuel pressure in relation to speed and/or temperature during starting of the internal combustion engine. is located. For this purpose, an outflow passage 23 communicates from the return spring chamber 19 of the pressure control valve 14 to the outflow chamber 24 of the pressure holding valve 22. The pressure retaining valve 22 has a stepped piston 25 as a movable valve member, which is movably supported in a stepped bore 26 and has a first pressure on the side opposite the valve spring 27. It has a surface 28 and a second pressure surface 29. 1st
The pressure surface 28 is used as a movable wall of the pressure holding chamber 31,
The second pressure surface 29 serves as a movable wall of the outflow chamber 24. The valve spring 27 is arranged in a spring chamber 32 , which is connected via a leakage line 33 to the suction line 34 of the feed pump 6 . The stage piston 25 has a small diameter control section 35 with a second pressure surface 29 facing the outlet chamber 24 and a large diameter pressure holding section 36, the large diameter pressure holding section 36 having one side. A pressure holding chamber 31 is formed by the first pressure surface 28, and a spring chamber 32 is formed on the other surface. Valve spring 27 forces piston 25 into the set position shown when feed pump 6 is not active. That is, in this position the control section 35 closes the outlet 37 leading to the suction conduit 34;
A pressure-retaining section 36 circumferentially closes a ring groove 38 formed in the wall of the stepped bore 26. S-ngu groove 3
From 8, a pressure holding line 39 leads to the regulating line 12 upstream of the pressure control valve 14. A temperature sensitive member 42, such as an expansion member or a metal spring, is inserted into the outflow chamber 24.
The actuating pin 41 is inserted, which actuates the control section 35 of the stage piston 25 to control the stage piston 25 when the internal combustion engine reaches the load operating temperature. 34 to the open position. Outlet 3 while the temperature is below the load operating temperature.
7 are closed. Thus, when the internal combustion engine is started at load operating temperature, the temperature sensitive element maintains the stepped piston 25 via the actuating pin 41 in a position in which the outlet 37 to the suction conduit 34 is open, and The fuel can flow back to the suction conduit 34 without pressure from the return spring chamber 19 of the pressure control valve 14 via the outflow passage 23 and the open pressure holding valve 22, and the injection start timing is adjusted in proportion to the rotational speed. Therefore, the pressure in the suction chamber 8 and thus in the working chamber 4 changes as a function of the rotational speed, primarily due to the force of the control spring 16 acting on the piston 15.

On the other hand, if the internal combustion engine is started below the load operating temperature, the pressure holding valve 22 is closed and the regulating piston 3 is in the "lag position" until the starting speed reaches approximately 15 Orpm. occupies . Pressure holding valve 22
As a result of the fact that the
The fuel pressure rising within pushes the regulating piston 3 into the "advance position". According to the invention, in this case the pressure holding valve 22
The tension of the valve spring 27 is set as follows. That is, the fuel pressure generated by the feed pump 6 and flowing through the pressure control valve 14 and the outflow passage 23 to the outflow chamber 24 of the pressure holding valve 22 is maintained at a predetermined pump rotational speed, for example, 10.
00 rpm, a pushing force is applied to the second pressure surface 29 to push and displace the stage piston 2-5. The stage piston 25 has a ring groove 38
is pushed to the position where it connects with the pressure holding chamber 31, and thereby the pushing force of the fuel exerted on the first pressure surface 28 moves the stage piston 25 to the position where it connects with the pressure holding chamber 31.
3, and this stop horn ξ43 is the pressure holding section 36.
This will prevent fuel from leaking into the spring chamber 32 from the circumferential surface of the spring chamber 32 as much as possible. In this way, the pressure holding valve 22 is opened independently of the temperature after a predetermined pump rotational speed, so that the fuel can flow out pressure-free from the return spring chamber I9 of the pressure control valve 14, so that the pressure The control valve 14 performs its normal control function to open the outlet 17 in proportion to the rotational speed to control the fuel pressure.

Reference numeral 44 designates a safety groove in the piston 15 of the pressure control valve 14. This safety channel 44 communicates with the fuel downstream of the throttle hole 20 and connects with a safety line 15 leading to the return line 18 in the event of overspeeding of the internal combustion engine or failure of the pressure-holding valve.

[Brief explanation of drawings]

The drawing is a circuit diagram partially showing an embodiment of the invention in longitudinal section.

Claims (1)

[Claims] (1) A fuel injection pump for an internal combustion engine, which is operated against a return force by liquid from a feed pump that pumps fluid in proportion to the rotational speed to adjust the injection start timing. The piston is provided with a control mechanism that controls the pressure of the liquid in proportion to the rotation speed via a pressure control valve, and the pressure control valve applies a return force between the pressure chamber and the return spring chamber. a movable wall which is movable against the flow rate and controls the outflow cross-sectional area, and which operates in conjunction with at least one operating characteristic value, such as the temperature of the engine, as well as at least one valve spring to control the flow rate of said liquid. In those types equipped with a pressure valve that additionally influences the pressure, the pressure valve has one pressure holding valve (
22), whose movable valve member (25) is loaded by a fluid pressure proportional to the rotational speed, and the pressure is increased from a predetermined pump rotational speed against the force of a correspondingly designed valve spring (27). Fuel injection pump, characterized in that the holding valve (22) can be shifted into an open position. 2 The pressure control valve (14) has a throttle connection port (20) between the pressure chamber (13) located downstream of the feed pump (6) and the return spring chamber (19), and the return spring Room (1
Outflow passage (23) leading from 9) to the pressure holding valve (22)
The fuel injection pump according to claim 1, having: 3. The movable valve member (25) of the pressure-retaining valve (22) is moved by the valve spring by means of a temperature-related actuator (41, 42), independent of the force generated by the liquid pressure proportional to the rotational speed. 3. The fuel injection pump according to claim 2, wherein the pressure holding valve (22) can be shifted to the open position against the force (27). 4. The movable valve member of the pressure holding valve (22) is a stepped piston (
25), and its first pressure surface (28
) is supplied with liquid pressure from the upstream side of the pressure control valve (14), and the second pressure surface (29) is supplied with liquid pressure from the downstream side 911j, respectively, against the force of the valve spring (27). A fuel injection pump according to claim 2 or 3. 5. Pressure holding valve (22
) is the position where the stage piston (25) interrupts the connection of the liquid pressure (39, 38) from the second flow side of the pressure control valve (4) to the first pressure surface (28) of the stage piston (25). occupy,
The second pressure surface (
The stage piston (25) is displaced against the force of the valve spring (27) by the liquid pressure proportional to the rotational speed acting on the pressure control valve (14), and the liquid (:39.38) on the upstream side of the pressure control valve (14) is displaced. ＞
5. A fuel injection pump according to claim 4, wherein the pump is in a position to create a connection between the first pressure surface (28) and the first pressure surface (28) to open the pressure holding valve (22).