Solenoid valve, in particular for fuel-injection pumps

• US 5,109,885 A
• Filed: 05/14/1991
• Issued: 05/05/1992
• Est. Priority Date: 11/15/1988
• Status: Expired due to Term

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Tauscher, Joachim
• Primary Examiner(s): Rosenthal, Arnold
• Application Number:
  US07/700,150
• Time in Patent Office: 357 Days
• Field of Search: 251/129.02, 251/129.16, 251/129.04, 137/554
• US Class Current: 137/554
• CPC Class Codes: F02D 2200/063 Lift of the valve needle
• CPC Class Codes: F02D 35/0007 using electrical feedback F02D35/0015 takes precedence
• CPC Class Codes: F02D 41/2096 for controlling piezoelectric injectors drive and control circuit for piezoelectric devices in general H10N30/802
• CPC Class Codes: F02D 41/28 Interface circuits
• CPC Class Codes: F02M 2200/21 Fuel-injection apparatus with piezoelectric or magnetostrictive elements
• CPC Class Codes: F02M 2200/24 Fuel-injection apparatus with sensors
• CPC Class Codes: F02M 59/466 Electrically operated valves, e.g. using electromagnetic or piezoelectric operating means
• CPC Class Codes: H01F 7/1607 Armatures entering the winding
• CPC Class Codes: Y10T 137/8242 Electrical

Abstract

In a solenoid valve, in particular for fuel-injection pumps, the end position of the valve needle (20) is detected when the valve seating (14) is fully opened by a position signalling device (46), which has a piezoelectric ceramic disk (47) arranged on the stroke-limit stop (28) for the valve needle (20). To transmit the valve-opening signal produced by the piezoelectric ceramic disk (47) when the valve needle (20) strikes the control element (40) of the solenoid valve, a double-conductor connecting cable (34), which is required for the excitation of the electromagnet (25) of the solenoid valve, is used. For this purpose, the circuit element (44) in the control element (40), which causes the electromagnet to be triggered, is connected downstream in the current direction, from the magnetic coil (24) via its feedback line (49) of the connecting cable (34), and the piezoelectric ceramic disk (47) is connected in parallel via the electrical outputs (51,52) of the series connection consisting of a diode ( 50) and of the magnetic coil (24).

Claims

1. A solenoid valve for a fuel injection pump comprising:

a housing defining a valve opening surrounded by a valve seat and coupled in fluid communication with a valve inlet and a valve outlet;

a valve needle moveable relative to the valve seat into a closed position into contact with the valve seat to close the valve opening and into an open position away from the valve seat to open the valve opening;

a stop member located adjacent to the valve needle to stop the valve needle upon reaching the open position;

an electromagnet including a winding for driving the valve needle into the closed position upon electrical excitation of the winding;

a spring member coupled to the valve needle for driving the valve needle into the open position;

a cable including a supply line coupled to one terminal of the winding and a feedback line coupled to another terminal of the winding for directing current through the winding;

a piezoelectric member coupled to the stop member for contacting the valve needle upon reaching the open position and generating a signal indicative thereof, wherein the output of the piezoelectric member conducting the higher potential is coupled between the winding and the feedback line and the other output of the piezoelectric member is coupled either between the supply line and winding or to ground or zero potential; and

a control unit including a first output coupled between the supply line and a voltage source for directing current from the voltage source to the winding, and a second output coupled between the feedback line and ground or zero potential by means of a switch element, wherein the open-position signal of the piezoelectric member is transmitted by the feedback line to the second output for tapping the signal.

2. A solenoid valve as defined in claim 1, further comprising a first diode coupled between the supply line and the winding wherein the conducting direction of the first diode is toward the winding.

3. A solenoid valve as defined in claim 1, wherein the control unit further includes a capacitor coupled between the second output and the switch element for tapping the open-position signal between the capacitor and the switch element.

4. A solenoid valve as defined in claim 1, wherein the switch element is a power transistor.

5. A solenoid valve as defined in claim 3, wherein the control unit further includes an amplifier coupled between the capacitor and the switch element.

6. A solenoid valve as defined in claim 3, wherein the control unit further includes a second diode coupled in series with a third diode between the first and second outputs, and the conducting direction of the second diode is directed toward the second output and the conducting direction of the third diode is directed toward the first output.