JPH0575894B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is an adjustment device for adjusting the injection start timing of a fuel injection pump of an internal combustion engine, and the invention is an adjustment device for adjusting the injection start timing of a fuel injection pump of an internal combustion engine. An adjusting piston is provided, which cooperates with the internal combustion engine and is loaded against a return force by a pressure medium supplied from the pump interior, the pressure of the pressure medium increasing the operating temperature of the internal combustion engine. variable in relation to a parameter and controllable by a pressure control valve, the pressure control valve having a control piston controlling the outflow opening from the pump internal combustion engine, the control piston being able to control the control pressure. The spring chamber is slidable against the force of the return spring and forms a pressure connection between the pressure side of the control piston and a spring chamber receiving the return spring, the spring chamber acting as a pressure retaining valve. In this case, the pressure state closing the spring chamber serves to obtain an increased pressure medium pressure in the internal combustion engine at room temperature, and when the specified temperature is reached, the electrical/mechanical the actuator, which is adapted to be controlled as a function of the operating temperature and the engine speed of the internal combustion engine, has a valve-closing element, and has a valve-closing element; The invention relates to a type in which the valve closing member is adapted to cooperate with a valve seat which limits the outflow opening for the pressure medium from the spring chamber.

Conventional technology For example, patent application publication number of the Federal Republic of Germany
In the regulating device known from DE 2648043, the regulating element is an expanded material element, the heating coil of which is adapted to open and close a switch that is dependent on the temperature of the cooling water or fuel. If the heating coil is not applied, the constant-pressure valve is not opened by the plunger, which causes a pressure to build up on the back side of the piston of the pressure-control valve, and thus a pressure in the pressure medium reservoir. As a result, the injection start timing is adjusted earlier. When the heating coil is applied, the ram of the expanding material member controls the constant pressure valve to open, which relieves the load on the piston of the pressure control valve, and causes the pressure side of the piston to control the outflow opening to open. As a result, the pressure in the pressure medium storage chamber decreases, whereby the regulating piston of the injection start timing adjustment device shifts the injection start timing later again, that is, to the normal position in the engine operating state.

By performing this early temperature-related adjustment during cold starting and switching off the regulating element, it is possible to quickly start the internal combustion engine when starting the internal combustion engine at cold temperature.

Problem to be Solved by the Invention However, such early adjustment poses a problem when the internal combustion engine reaches a high rotational speed range. This is because in such cases it is not possible to completely eliminate quite large engine noise and so-called knocking.

It is therefore an object of the invention to solve the problem of high engine noise and knocking in the high speed range with simple means and with high operational reliability.

Means for Solving the Problem In order to solve this problem, the configuration of the present invention includes:
In an adjusting device of the type mentioned at the outset, the adjusting element is of electromagnetically actuated design, and the current path for the solenoid valve, which is formed by the cooperating valve closing element and the valve seat, has two a switch is arranged, one of the switches being controllable in relation to the operating temperature of the internal combustion engine and the other switch being controllable in relation to the engine speed;
The pressure state that closes the spring chamber is released at a predetermined operating temperature or a predetermined engine speed.

Operation The operation of the adjusting device according to the invention will now be explained with reference to the embodiment shown in FIG. Fig. 1 shows a state in which the internal combustion engine is already warmed up after starting, but when starting at room temperature, switch 33,
34 are both closed, so the excitation coil 24 is energized and the valves 25 and 26 are closed. Therefore, the fuel flowing out of the spring chamber 28 has to open the pressure holding valve 20, and this additional opening pressure causes the pump internal chamber (pressure medium storage chamber) 1 to open.
The fuel pressure at 0 increases, and thereby the adjusting piston 12 is adjusted to advance the fuel injection timing.

For example, when the temperature of the fuel and the engine speed reach predetermined values, both switches 33, 34 and, in turn, the valves 25, 26 are opened, the pressure in the pump interior 10 decreases, and the regulation is quickly returned.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a pump housing 9 of a fuel injection pump and an injection start timing adjusting device 11 which acts as a regulating device, the adjusting piston 12 of which is actuated by a return spring 13. kept in position. The feed pump 14 sucks fuel from the fuel tank 15 into the pump inner chamber 10, and in the pump inner chamber 10, a compartment vane pump (not shown) generates a fuel pressure that is directly proportional to the pump rotation speed, and the height of this fuel pressure is equal to the pressure. defined by control valve 16.

When the pump rotational speed exceeds a predetermined rotational speed, the pressure in the pump interior 10 overcomes the spring force of the return spring 13 and moves the adjusting piston 12 to the new balance position; A roller ring (not shown) is rotated via pin 17. In other words, this changes the correspondence between the rotating lifting disk and the roller ring, so that the lifting disk is lifted by the rollers of the roller ring and adjusted earlier. As a result, the injection start time becomes correspondingly earlier.

The room temperature start acceleration valve 19, which is an adjustment member for releasing the closed state of the spring chamber 28, which will be described later, has a pressure solenoid valve 18 and a pressure holding valve 20 connected in parallel to the valve. A ball 21 loaded by a return spring 23 is mounted on the valve seat 22 of the pressure holding valve 20.
is touching from the inside. The pressure solenoid valve 18 has an excitation coil 24 which is designed as a valve closing member 25 and has an armature that cooperates with a valve seat 26 . A supply line 27 from the spring chamber 28 of the pressure control valve 16 leads to both valve seats 22 , 26 . The spring chamber 28 is closed by a control piston 29 loaded by a return spring 30, the control surface 31 of the control piston 29 controlling the opening and closing of the control opening 32 so that the Adjust the predetermined fuel pressure.

In the first embodiment shown in FIG.
and a switch 34 related to the rotational speed of the internal combustion engine are connected in series to the current path 35 of the excitation coil 24 one after the other. Since the fuel pressure in the pump chamber 10 is directly proportional to the engine speed, the engine speed-related switch 34 may be a switch loaded by the fuel pressure.

In the regulating device of FIG. 1, the cold start acceleration valve 19 is shown in the case where the excitation coil 24 is in the rest position and the valves 25, 26 are open. In other words, this indicates a warm internal combustion engine condition in a high rotational speed range.

When starting an internal combustion engine at normal temperature, the temperature-related thermoswitch 33 and the engine speed-related switch 34 are each in a closed position, so that the excitation coil 24, which is now energized, is in its closed position. It is in its working position and valves 25, 26 are closed. As a result, some of the fuel flowing through the throttle hole 36 provided in the control piston 29 is transferred to the pressure holding valve 2 in order to flow out via the outflow conduit 37.
0 valves 21, 22 have to be opened, in which case an additional opening pressure is applied, as is known, to the pump interior 1.
The fuel pressure at 0 is increased so that, as already mentioned, the adjusting piston 12 adjusts the injection start timing in the earlier direction.

When a predetermined temperature or a predetermined rotational speed (pressure) is achieved or exceeded, the thermoswitch 33 and/or the switch 34 in each case opens the current path, so that the valves 25, 26 are opened and the outflow conduit is opened. As a result of the outflow of fuel via 38, the closed pressure state of the spring chamber 28 is released and the regulation is therefore restored earlier.

Also in FIG. 2 showing the second embodiment, members that are the same as or similar to those in FIG. 1 are given the same reference numerals. In this embodiment, the normal temperature start acceleration valve 49
is designed as a tension solenoid valve whose excitation coil 44 keeps the solenoid valves 25, 26 open in its working position against the force of a compression spring 48.
The force of the compression spring 48 is adjusted in such a way that in the working position of the excitation coil 44, ie when the valves 25, 26 are open, a pressure holding force is generated thereby which relieves the pressure in the spring chamber 28. With this configuration, a separate pressure holding valve is not required. In this second embodiment, unlike the first embodiment, a temperature-related thermoswitch 33 and a speed- or pressure-related switch 34 are connected in parallel to the current path 35.

FIG. 2 shows a control device for a hot internal combustion engine operating in a high speed range, with valves 25, 26 open, ie the cold start function is not active. During a cold start of the internal combustion engine, both switches 33, 34 open the current path 35, and the valves 25, 26 are closed by the compression spring 48. When a predetermined temperature or rotational speed is exceeded,
Each switch 33, 34 closes the current path 35, so that the excitation coil 44 assumes the working position shown, whereby early adjustment is restored via the open valves 25, 26.

It is also possible to provide the embodiment of FIG. 2 with a pressure holding valve as shown in FIG. In this case, the closing spring of the armature must have a greater spring force than the spring in the pressure-holding valve in order to reliably open the pressure-holding valve without opening the solenoid valve.

Effects of the Invention With the structure of the present invention, relatively large engine noise and knocking at high rotational speeds, which were problems in the prior art, can be solved by simple technical means and with great operational reliability. can. The invention differs from the prior art by using an electro-mechanical adjustment element instead of the expandable material element acting as the adjustment element and controlling this adjustment element not only in relation to the temperature but also in relation to the engine speed. It is based on the idea that shortcomings can be avoided.

[Brief explanation of the drawing]

FIG. 1 schematically shows a first embodiment of an adjusting device according to the invention, and FIG. 2 schematically shows a second embodiment. 9...Pump casing, 10...Pump inner chamber, 1
DESCRIPTION OF SYMBOLS 1... Injection start timing adjustment device, 12... Adjustment piston, 13... Return spring, 14... Feed pump, 1
5... Fuel tank, 16... Pressure control valve, 17... Pin, 18... Pressing solenoid valve, 19, 49... Room temperature start acceleration valve, 20... Pressure holding valve, 21... Ball, 22... Valve seat, 23... Return spring, 24... Excitation coil, 25...
Valve closing member, 26... Valve seat, 27... Supply conduit, 28
...Spring chamber, 29...Control piston, 30...Return spring, 31...Control surface, 32...Control opening, 33...Thermo switch, 34...Switch, 35...Current path, 3
6... Throttle hole, 37, 38... Outflow conduit, 44... Excitation coil, 48... Compression spring.

Claims (1)

[Scope of Claims] 1. An adjusting device for adjusting the injection start timing of a fuel injection pump of an internal combustion engine, which comprises an adjusting piston 12 that cooperates with a cam transmission mechanism of a plunger of the injection pump to adjust the injection start timing. and the adjusting piston 12 is loaded against a return force by a pressure medium supplied from the pump interior 10, the pressure of the pressure medium being variable as a function of the operating parameters of the internal combustion engine. and is controllable by a pressure control valve 16, which has a control piston 29 for controlling the outflow opening from the pump internal combustion engine 10, which control piston 29 is controlled by a control pressure. The pressure side of the control piston 29 and the return spring 30 are slidable against the force of the return spring 30.
a pressure connection is formed between the spring chamber 28 and the spring chamber 28 which receives the pressure condition which can be relieved via the pressure retaining valve 20 and which in this case closes the spring chamber 28. acts in order to obtain an increased pressure medium pressure in the internal combustion engine at room temperature, and can be released by an electro-mechanical regulating member when a specified temperature is reached, in which case the regulating member is adapted to be controlled as a function of the operating temperature and the engine speed, and has a valve closing element 25 which opens an outlet opening for the pressure medium from the spring chamber 28. In the version adapted to cooperate with the limiting valve seat 26, the adjusting member is of electromagnetically actuated construction and is formed by the valve closing member 25 and the valve seat 26 cooperating with each other. In the current path 35 for the solenoid valves 25, 26, 2
Two switches 33, 34 are arranged, of which one switch 33 can be controlled in relation to the operating temperature of the internal combustion engine, and the other switch 34 can be controlled in relation to the engine speed. ,
In this case, the pressure state closing the spring chamber 28 is
1. An adjustment device for adjusting the injection start timing of a fuel injection pump of an internal combustion engine, characterized in that it is released at a predetermined operating temperature or a predetermined engine speed or higher. 2. The solenoid valve is constructed as a tension solenoid valve 49, the valve closing member 25 of which is loaded in the closing direction by a compression spring 48 and assumes an open position when the solenoid valve is closed. 2. The adjusting device according to claim 1, wherein the valve closing member 25 together with the pressure spring 48 acts as a pressure retaining valve. 3. Adjustment device according to claim 1, characterized in that the solenoid valve is constructed as a push-on solenoid valve 18 with a valve closing member 25 which is adapted to occupy a closed position when the closing connection is made. 4 Switch 3 that can be controlled in relation to engine speed
4. The regulating device according to claim 1, wherein 4 is a switch that can be loaded by the pressure of the fuel in the pump interior. 5. Adjustment device according to claim 3, in which the pressure solenoid valve 18 and the pressure holding valve 20 are arranged in one common housing 9.