Method for Operating a High Pressure Pump of an Injection System and an Injection System

Abstract

A method for operating a high-pressure pump of an injection system and an injection system is provided. The method relates to a switching off of additional pulses, which are applied to a valve of the high-pressure pump, if the determined coil temperature of the valve exceeds a limit value. The method is, for instance, then carried out if additional pulses are applied to the valve to reduce noise (whisper function). Current information and voltage information from the control signal of the valve of the high-pressure pump are used to measure the temperature of the valve and switch off additional current pulses through this information if there is a risk of the valve overheating. The disclosure further describes an injection system of a combustion engine, wherein the injection system comprises a high-pressure pump having a valve and a corresponding control unit.

Claims

1. A method for operating a high pressure pump of an injection system of an internal combustion engine in which a valve in the high pressure pump is opened and/or closed by way of a control unit by means of influencing the coil of the valve by way of a control pulse of the type mentioned, the method comprising the following steps: measuring an electrical current that the valve uses to open and/or to close; measuring an electrical voltage that is prevailing at the valve; calculating an electrical resistance of the coil; determining a coil temperature from the calculated coil resistance; and switching off additional pulses with which the valve is influenced if the determined coil temperature exceeds a limit value.

2. The method of claim 1, where additional pulses with which the valve is influenced so as to reduce noise development are switched off.

3. The method of claim 1, wherein the current that the valve uses to open and/or to close is measured by a shunt resistor in the control unit.

4. The method of claim 1, wherein with the knowledge of the coil resistance a resistance is measured at normal temperature and stored for the calculation of the prevailing coil temperature value.

5. The method of claim 1, wherein an inlet valve is controlled in an identical manner to the valve in the high pressure pump.

6. An injection system of an internal combustion engine comprising: a high pressure pump having a valve and a control unit for opening and/or closing the valve by means of influencing a coil of the valve by way of a current pulse;: a device for measuring the electrical current that the valve uses to open and/or to close; a device for measuring the electrical voltage that is prevailing at the valve; a device for calculating the electrical resistance of the coil; a device for determining the coil temperature from the calculated coil resistance; a device for influencing the valve by way of additional pulses; and a device for switching off the device for influencing the valve by way of additional pulses if the determined coil temperature exceeds a limit value.

7. The injection system of claim 6, wherein the device for influencing the valve by way of additional pulses is a device for influencing the valve by way of pulses so as to reduce the noise development.

8. The injection system of claim 6, wherein the device for measuring the electrical current that the valve uses to open and/or to close is a shunt resistor in the control unit.

9. The injection system of claim 6, further comprising a device for measuring the coil resistance at normal temperature.

10. The injection system of claim 6, wherein the valve in the high pressure pump is an inlet valve in the high pressure pump.

Description

DESCRIPTION OF DRAWINGS

[0023] FIG. 1 illustrates a schematic longitudinal section view of an exemplary high-pressure pump having a valve.

[0024] FIG. 2 illustrates a flow diagram of the method in accordance with the exemplary high-pressure pump.

[0025] Like reference symbols in the various drawings indicate like elements.

DETAILED DESCRIPTION

[0026] FIG. 1 illustrates a schematic view of a high-pressure pump 10 of an injection system of a combustion engine. The pump 10 includes a pump housing 12 and is embodied in the case of the example as a radial piston pump. A pump piston 14 is movably mounted in the pump housing 12. A pressure chamber 16 is located in the pump housing 12 at one end of the pump piston 14. To be able to fill the pressure chamber 16 with fluid, the pressure chamber includes a supply line 18 in which is arranged a valve 20 that is shown as an inlet valve. The valve 20 that is shown as an inlet valve may be a digitally controlled valve. The valve 20 facilitates the procedure of filling the pressure chamber 16 and prevents the fluid flowing back out of the supply line 18 during the filling procedure. The pressure chamber 16 includes moreover a discharge line 22 in which a further valve 24 that is embodied as an outlet valve is arranged. As a result, fluid can be discharged from the pressure chamber 16.

[0027] Furthermore, and in some examples, the pump 10 includes a drive shaft 26 that is operatively connected to an eccentric cam 28 and can rotate in a direction of rotation D in the clockwise direction.

[0028] In some implementations, the valve includes a valve housing having a cavity in which a spring 32, a rod 34, and a sealing element 36 are arranged. The spring 32 pretensions the sealing element 36 by way of the rod 34, in that the spring is supported on a wall of the cavity. Furthermore, a seal seat 38 that is fixedly arranged opposite the valve housing 29 may be located in the cavity and the seal seat includes through-going cut-outs. Fluid may flow by way of the through-going cut-outs if the sealing element 36 is not lying against the seal seat 38. In some examples, the valve 20 includes an actuator 42. The actuator 42 may be a magnetic coil. The rod 34 may be arranged in part within the actuator 42 and may be actuated by the actuator 42. The precise construction of a valve of this type is described in the document DE 10 2011 075 269 A1 already mentioned in the introduction. The valve is designed and functions in such a manner that the noise development during opening the valve is reduced by means of applying additional current pulses. This so-called whispering function is described in detail in the above mentioned publication.

[0029] In the case of the method in accordance with the disclosure, these additional pulses with which the valve is influenced so as to reduce noise development are now switched off (whispering function) if the determined coil temperature of the valve exceeds a limit value. In so doing, the whispering pulse is not blindly switched off once a specific rotational speed has been achieved but rather, as illustrated in FIG. 2, the electrical current that is used by the valve to open is measured in Step 1. In Step 2, the electrical voltage that is prevailing at the valve is measured. The resistance of the valve coil is calculated from the two values according to the formula R=U/I (Step 3). This value is dependent upon the coil resistance at nominal temperature (20 C.) and the coil temperature. The coil temperature is thus unambiguously allocated to a temperature in the case of a specific coil. The coil temperature may then be calculated as follows (Step 4):

Rt=R20*(1+a20*(t20 C.)).fwdarw.t=20 C.+(Rt/R201)/a20.

[0030] If in so doing a temperature is determined at which damage may occur to the coil, the whispering pulse is switched off (Step 5). However, this consequently only occurs when there is an actual risk of damage and not just as a precaution. As a result of switching off the pulse, the electrical loading on the pump is less.

[0031] The parameters included in the above equation have the following meaning: [0032] Rt=Resistance at temperature t [0033] R20=Resistance at 20 C. [0034] t=Temperature being determined [0035] a20=Temperature coefficient

[0036] A number of implementations have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the disclosure. Accordingly, other implementations are within the scope of the following claims.