CZ2020569A3 - Actuator for fuel dose control - Google Patents

Abstract

Actuator for controlling the amount of fuel injected by a high-pressure diesel fuel injection pump, comprising a rotary electromagnet with a rotor (1) on a shaft (3), the shaft (3) being mounted in at least one bearing (5) and carrying a control lever (7) pumps. The rotor (1) comprises two rectangular fingers (2) made of magnetically mild steel, which are arranged at a distance on a common shaft (3) in the stator (6). An annular coil (4), firmly connected to the stator (6), extends into the space between the thumbs (2). The shaft (3) is provided with a return spring and at least one position sensor (9).

Description

Actuator for fuel dose control

Field of technology

The invention relates to an actuator for controlling a dose of fuel injected by a high-pressure fuel injection pump of a diesel engine, comprising a rotary electromagnet with a rotor on a shaft, the shaft being mounted in at least one bearing and carrying a lever for controlling the pump.

Prior art

An injection valve and an injection system with such an injection valve are known from US 2013037622. The injection valve is located in the fuel system only at the very end, ie in front of the combustion chamber of the engine compartment, into which fuel is injected on the basis of an electrical impulse from the control unit. The injector of US 2013037622 is essentially a double-acting solenoid with a core, solenoid coils and return springs that keep the solenoid in the home position. The amount of fuel injected by this valve is regulated in such a way that an electrical impulse from the control unit applied to one of the coils causes the rod to move upwards or downwards. This movement opens one of the cone valves to which the fuel from the pressure tanks is already supplied.

Furthermore, an actuator for controlling the dose of fuel injected by a high-pressure fuel injection pump of a diesel engine is known. Such an actuator is an electromechanical device capable of adjusting the exact angle of rotation of its shaft. It is therefore a rotary proportional electromagnet with a position sensor. During the operation of the engine, the entire injection system and thus the actuator is exposed to intense vibrations in a wide range of operating temperatures with the possible action of other environmental influences of the environment and chemicals.

Most known solutions of rotary electromagnets use permanent magnets which are glued to the rotor. In this type of construction, the phenomenon is used when the stator coil together with its poles is an electromagnet and, depending on the direction of current through the coil, attracts or repels suitably located poles of the permanent magnet. Such types of constructions can also have a higher number of poles than two, in order to achieve a better course of the output torque at the required working angle. In such a case, the permanent magnet must be precisely positioned due to the high sensitivity of the location to the output parameters of the actuator.

Another undesirable scattering of the output parameters results from the differences in the magnetic fields of the individual pieces of permanent magnets.

When using permanent magnets, a return spring is usually included, which allows you to return to the zero position. Without this spring, it is necessary to generate a certain moment to return to the zero position, which is necessary for the passage of the permanent magnet on the rotor through the poles of the stator to which it is attracted. The return spring placed in this way, due to its adjustment and differences in the characteristics, introduces further dispersion of the monitored parameters for the individual pieces of actuators.

In known solutions, the connection of the actuator coil and possibly also the position sensor is not made in such a way that the actuator is protected against undesired effects from external influences. Above all, there is a lack of a sufficient degree of protection by the cover, ie resistance to the effects of oil substances, water penetration and foreign particles.

The angle sensor for measuring in the feedback loop is part of the actuator itself and cannot be easily replaced by the service. The sensor integrated in this way itself does not have an additional auxiliary cover that would protect it against adverse effects that may act inside the actuator body.

- 1 CZ 2020 - 569 A3

The mounting of moving parts of known types of actuators is not suitably dimensioned to ensure service life under the action of operating vibrations in demanding conditions of some target applications.

The essence of the invention

The disadvantages of the prior art are eliminated by the actuator for controlling the dose of fuel injected by a high-pressure fuel injection pump of a diesel engine, comprising a rotary electromagnet with a rotor on a shaft, where the shaft is mounted in at least one bearing and carries a pump control lever according to the invention. that the rotor comprises two rectangular fingers of magnetically soft steel, which are arranged at a distance on a common shaft in the stator, an annular coil firmly connected to the stator extending into the space between the fingers. The shaft is provided with a return spring and at least one position sensor.

The actuator according to the invention makes it possible to obtain a significantly lower variance of the output parameters. The advantage is the absence of permanent magnets, which in known embodiments cause a considerable part of such scattering.

The rotor of the actuator is composed of several parts, so it can be easily mounted as a whole, due to the location of the coil in the space between the fingers of the rotor. This makes efficient use of space and reduces the weight of the actuator.

The actuator can be placed in the pump flange to increase the rigidity of the unit and thus increase the vibration resistance. This concept also reduces the overall weight and improves the heat dissipation ability of the actuator coil.

It is advantageous if the thumbs on the common shaft are arranged in an overlapping manner.

According to a preferred embodiment, the return spring is connected to a lever for controlling the pump.

According to another preferred embodiment, both thumbs are in the shape of a rectangle with circularly rounded shorter sides which copy the inner surface of the stator.

According to yet another preferred embodiment, the stator is pressed into a housing which is hermetically sealed by a lid.

According to another preferred embodiment, the shaft is mounted in a pair of bearings arranged in the housing.

Explanation of drawings

The invention will be described in more detail by way of an example of a specific embodiment of a fuel dose control actuator according to the invention, shown in the drawings, in which the individual figures show:

Fig. 1 - longitudinal section of the actuator;

Fig. 2 - cross section of the actuator of Fig. 1.

Examples of embodiments of the invention

An exemplary embodiment of an actuator for controlling the dose of fuel injected by a high-pressure diesel fuel injection pump, according to Figs. 1 and 2, comprises a housing 8 which is hermetically sealed by a lid 10 against external influences up to IP69K according to EN 60529.

-2EN 2020 - 569 A3

A stator 6 is pressed into the housing 8 and a rotor 1 is mounted in a pair of bearings 5, formed by a shaft 3, which carries two overlapping rectangular fingers 2 of magnetically soft steel. The shaft 3 further carries a lever 7 for controlling the injection pump. A return spring (not shown) is connected to the lever 7 to return the shaft 3 to the initial position. The return spring pushes the lever 7 using the pump control rod.

It will be apparent to those skilled in the art that instead of two bearings 5, it is possible to mount the shaft 3 in one axially radial bearing.

In an embodiment not shown, the thumbs 2 do not have to be arranged on the shaft 3 in an overlapping manner. In this case, however, the arrangement of the stator 6 would have to be adjusted accordingly.

In the exemplary embodiment shown, one encapsulated position sensor 9 is arranged at each end of the shaft 3, for measuring the angle of rotation of the actuator. The second position sensor 9 is optional and reduces the risk of the motor running in emergency mode in the event of a failure of the primary position sensor 9.

The thumbs 2 are arranged at a distance from each other on the shaft 3 of the rotor 1. In the exemplary embodiment shown, both thumbs 2 have the shape of a rectangle with circularly rounded shorter sides which copy the inner surface of the stator 6.

An annular coil 4, firmly connected to the stator 6, extends into the space between the thumbs 2.

After applying direct current to the coil 4, a magnetic field is created in the magnetic circuit, thanks to which a torque is generated acting on the rotor 1 with the thumb 2 and causing the lever 7 to rotate, which is connected to the control mechanism of the regulated injection pump. 9 position sensors are used to provide feedback.

The rotary movement of the actuator is transformed by a lever 7 into a linear movement of the control rod. Together with the engine control unit and other system components, the injection pump fitted in this way is part of the injection system of the machine or vehicle engine.

Industrial applicability

The actuator for controlling the dose of fuel injected by the high-pressure fuel injection pump of the diesel engine serves for precise dosing of the fuel of the diesel engine by controlling the position of the control rod of the high-pressure injection pump.

Claims (6)

PATENT CLAIMS An actuator for controlling a dose of fuel injected by a high-pressure diesel fuel injection pump, comprising a rotary electromagnet with a rotor (1) on a shaft (3), wherein the shaft (3) is mounted in at least one bearing (5) and carries a lever (7) for controlling the pump, characterized in that the rotor (1) comprises two rectangular thumbs (2) of magnetically mild steel, which are arranged at a distance on a common shaft (3) in the stator (6), into the space between the thumbs (2) an annular coil (4), fixedly connected to the stator (6), engages, and the shaft (3) is provided with a return spring and at least one position sensor (9). Actuator according to Claim 1, characterized in that the thumbs (2) are arranged in an overlap on the common shaft (3). Actuator according to Claim 1 or 2, characterized in that the return spring is connected to a lever (7) for actuating the pump. Actuator according to any one of claims 1, 2 or 3, characterized in that both thumbs (2) have the shape of a rectangle with circularly rounded shorter sides which copy the inner surface of the stator (6). Actuator according to any one of claims 1, 2, 3 or 4, characterized in that the stator (6) is pressed into a housing (8) which is hermetically sealed by a lid (10). Actuator according to any one of claims 1, 2, 3, 4 or 5, characterized in that the shaft (3) is mounted in a pair of bearings (5) arranged in the housing (8).