# US 10,767,579 B2 · Monitoring the function of solenoid valves for fuel injection systems

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- Number: US 10,767,579 B2
- Document ID: US10767579B2
- Status: Granted
- Kind: B2
- Application number: 16/335,301
- Filed: 2017-08-07
- Published: 2020-01-16
- Granted: 2020-09-08
- Earliest claimed: 2016-09-22
- Assignees: Robert Bosch GmbH
- Applicants: Robert Bosch GmbH
- Inventors: Claudia Gasselsdorfer; Peter Christiner
- Web page: https://patentgrep.com/patent/US10767579B2

## CPC

- F02D 41/0027: {the fuel being gaseous (non-electrical control F02D19/02)}
- F02D 19/02: peculiar to engines working with gaseous fuels
- F02D 19/024: {by controlling fuel injectors}
- F02D 19/025: {Failure diagnosis or prevention; Safety measures; Testing}
- F02D 19/029: {Determining density, viscosity, concentration or composition}
- F02D 41/1401: {characterised by the control or regulation method (F02D41/1473, F02D41/1477 take precedence)}
- F02D 41/144: {Sensor in intake manifold}
- F02D 41/20: Output circuits, e.g. for controlling currents in command coils
- F02D 41/221: {relating to the failure of actuators or electrically driven elements}
- F02D 41/222: {relating to the failure of sensors or parameter detection devices}
- F02D 41/40: with means for controlling injection timing or duration
- F02D 41/401: {Controlling injection timing (F02D41/402 takes precedence)}
- F02M 21/023: {Valves; Pressure or flow regulators in the fuel supply or return system}
- F02D 2041/1433: {using a model or simulation of the system}
- F02D 2041/2055: {with means for determining actual opening or closing time}
- F02D 2041/2058: {using information of the actual current value}
- F02D 2041/225: {Leakage detection}
- F02D 2200/0614: Actual fuel mass or fuel injection amount
- F02D 2200/0618: Actual fuel injection timing or delay, e.g. determined from fuel pressure drop
- Y02T 10/30: Use of alternative fuels, e.g. biofuels
- Y02T 10/40: Engine management systems
- F02D: CONTROLLING COMBUSTION ENGINES (vehicle fittings, acting on a single sub-unit only, for automatically controlling vehicle speed B60K31/00; conjoint control of vehicle sub-units of different type or different function, road vehicle drive control systems for purposes other than the control of a single sub-unit B60W)
- F02M: SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
- Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION

## Abstract

The invention relates to a method (100) for operating a solenoid valve (1) for metering a fuel (2) in a fuel injection system (3). The solenoid valve can be actuated against a restoring force (12) by an electromagnet (11), wherein •the time curve l(t) of the current I flowing through the electromagnet (11) and/or the time curve U(t) of the voltage U applied to the electromagnet (11) are detected during at least one opening process of the solenoid valve (1). The opening time tON and the closing time tOFF of the solenoid valve (1) are evaluated (110) from the time curve I(t) and/or U(t), and the actual opening duration TT=tOFF−tON of the solenoid valve (1) is compared (140) with a reference value TR and/or •the mass flow dm/dt flowing through the solenoid valve (1) is detected (120) and compared (142) with a reference value MR during at least one opening process of the solenoid valve (1); and/or a leakage dm′/dt of fuel (2) through the solenoid valve (1) is detected (130) in the closed state of the solenoid valve (1). The invention also relates to a corresponding controller (5), a fuel injection system (3), and a computer program product.

## Claims

### Claim 1

A method (100) for operating a solenoid valve (1) for metering a fuel (2) in a fuel injection system (3), wherein the solenoid valve is configured to be actuated counter to a return force (12) by an electromagnet (11), the method comprising:
detecting, at at least one opening of the solenoid valve (1), either or both of a temporal profile I(t) of a current I flowing through the electromagnet (11) and a temporal profile U(t) of a voltage U applied to the electromagnet (11);
evaluating, from either or both of the temporal profile I(t) and the temporal profile U(t), an opening time tON and a closure time tOFF of the solenoid valve (1);
comparing an actual opening duration TT=tOFF−tON of the solenoid valve (1) with a reference value TR; and
compensating or correcting a difference in the actual opening duration TT with respect to the reference value TR by changing the voltage temporal profile u(t) applied to the electromagnet (11) or the current temporal profile i(t) applied to the electromagnet (11).

### Claim 2 (depends on 1)

The method (100) as claimed in claim 1, the method further comprising evaluating a degree of wear W of the solenoid valve (1), which influences a mass flow dm/dt through the solenoid valve (1), from either or both of the temporal profile I(t) and the temporal profile U(t).

### Claim 3 (depends on 2)

The method (100) as claimed in claim 2, wherein the degree of wear W is retrieved from a calibration database (4).

### Claim 4 (depends on 1)

The method (100) as claimed in claim 1, wherein the solenoid valve (1) meters fuel (2) into an intake manifold (31) of the fuel injection system (3) and a leakage dm′/dt of fuel (2) passing through the solenoid valve (1) is detected by measuring a gas composition (32) in the intake manifold (31).

### Claim 5 (depends on 4)

The method (100) as claimed in claim 4, wherein the gas composition (32) is measured by measuring a speed of sound c in the intake manifold (31).

### Claim 6 (depends on 1)

The method (100) as claimed in claim 1, the method further comprising evaluating an estimation of the remaining lifetime of the solenoid valve (1) from archived detected values of the opening duration TT.

### Claim 7

A controller (5) for operating a solenoid valve (1) that is configured to be actuated counter to a return force (12) by an electromagnet (11), the controller comprising a calibration database (4) configured to assign a degree of wear W of the solenoid valve (1) to either or both of a temporal profile I(t) of a current I flowing through the electromagnet (11) and to a temporal profile U(t) of a voltage U applied to the electromagnet (11).

### Claim 8

A fuel injection system (3) comprising
at least one intake manifold (31); and
at least one solenoid valve (1) for metering fuel (2) into the intake manifold (31), wherein a measurement apparatus (33) for measuring a speed of sound c in the intake manifold (31) is arranged in or on the intake manifold (31), downstream of the solenoid valve (1).

### Claim 9 (depends on 8)

The fuel injection system (3) as claimed in claim 8, wherein the measurement apparatus (33) comprises at least one oscillation generator (34).

### Claim 10 (depends on 1)

A non-transitory computer-readable medium storing instructions that, when executed by a processor of a computer, cause the computer to perform the method as claimed in claim 1.

### Claim 11 (depends on 1)

The method (100) as claimed in claim 1 further comprising detecting, at at least one opening of the solenoid valve (1), a mass flow dm/dt through the solenoid valve (1) and comparing the mass flow dm/dt with a reference value MR.

### Claim 12 (depends on 11)

The method (100) as claimed in claim 11, the method further comprising compensating or correcting a difference in the mass flow dm/dt with respect to the reference value MR by changing the voltage temporal profile u(t) applied to the electromagnet (11) or the current temporal profile i(t) applied to the electromagnet (11).

### Claim 13 (depends on 11)

The method (100) as claimed in claim 11, the method further comprising evaluating an estimation of the remaining lifetime of the solenoid valve (1) from archived detected values of the mass flow dm/dt.

### Claim 14 (depends on 1)

The method (100) as claimed in claim 1 further comprising detecting, in a closed state of the solenoid valve (1), a leakage dm′/dt of fuel (2) passing through the solenoid valve (1).

### Claim 15 (depends on 14)

The method (100) as claimed in claim 14, the method further comprising evaluating an estimation of the remaining lifetime of the solenoid valve (1) from archived detected values of the leakage dm′/dt.