Parallel circuit for driving an electromagnetic load

• US 5,731,946 A
• Filed: 12/26/1995
• Issued: 03/24/1998
• Est. Priority Date: 04/27/1994
• Status: Expired due to Fees

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Kahr, Viktor
• Primary Examiner(s): Gaffin, Jeffrey A.
• Assistant Examiner(s): Huynh, Thuy-Trang N.
• Application Number:
  US08/571,836
• Time in Patent Office: 819 Days
• Field of Search: 361/154, 361/187, 361/189, 361/190
• US Class Current: 361/154
• CPC Class Codes: F01L 9/20 by electric means
• CPC Class Codes: F02D 2041/001 for engines with variable valve actuation
• CPC Class Codes: F02D 2041/2017 using means for creating a boost current or using reference switching
• CPC Class Codes: F02D 2041/2058 using information of the actual current value
• CPC Class Codes: F02D 2041/2075 Type of transistors or particular use thereof
• CPC Class Codes: F02D 41/20 Output circuits, e.g. for controlling currents in command coils
• CPC Class Codes: H01F 7/1805 Circuit arrangements for holding the operation of electromagnets or for holding the armature in attracted position with reduced energising current for holding relay armature in attracted position with reduced energising current H01H47/04; quick energising of electro-dynamic machines H02P9/08; for quickly de-energising of dynamo-electric generators H02P9/123

Abstract

A device for driving a load, in particular an electromagnetic load. The device includes a current detector for detecting the current flowing through the load, a power transistor connected in series to the load, which is triggered in dependence upon the current flowing through the load, and a further transistor arranged in parallel to the power transistor. The device has the advantage of reducing the power dissipation in the power transistor.

Claims

1. A device for driving an electromagnetic load, comprising:

current detector means for detecting a current flowing through the load;

control means connected in series with the load, the control means being activated to conduct in dependence upon the current flowing through the load; and

a circuit component arranged parallel to the control means, thereby forming a parallel circuit arrangement, the parallel circuit arrangement being connected in series with the current detector means;

wherein the control means conducts a portion of the current flowing through the load when the circuit component is activated.

2. The device of claim 1, further comprising a resistor arranged in series to the circuit component.

3. The device of claim 2, wherein a resistance of the series combination of the resistor and the circuit component is smaller than a resistance of the control means.

4. The device of claim 1, wherein the control means is activated in dependence upon a difference between the current flowing through the load and a setpoint current.

5. The device of claim 1, wherein the circuit component operates as a switch.

6. The device of claim 1, wherein at the beginning of an activation for driving the load, the circuit component and the control means become fully conductive.

7. The device of claim 1, wherein each of the control means and the circuit component conducts a portion of the current flowing through the load when both the control means and the circuit component are activated.