Servocylinder unit

• US 4,972,819 A
• Filed: 09/14/1988
• Issued: 11/27/1990
• Est. Priority Date: 03/22/1986
• Status: Expired due to Term

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Engfer, Ortwin
• Primary Examiner(s): Miller, Carl Stuart
• Application Number:
  US07/271,753
• Time in Patent Office: 804 Days
• Field of Search: 123/370, 123/372, 123/385, 123/386, 123/387, 180/197
• US Class Current: 123/370
• CPC Class Codes: F02B 3/06 with compression ignition compression ignition engines using air or gas for blowing fuel into compressed air in cylinder F02B13/02
• CPC Class Codes: F02D 11/08 of the pneumatic type
• CPC Class Codes: F02D 17/04 rendering engines inoperative or idling, e.g. caused by abnormal conditions dependent on lubricating conditions F01M1/22; dependent on cooling F01P5/14

Abstract

A servocylinder unit for adjusting an amount of fuel fed to a vehicle drive engine and comprising a piston displaceable in a cylinder, a first pre-stressed spring for biasing the piston to its initial position, a first stop for supporting the first spring and displaceable along the longitudinal axis of the cylinder, a second pre-stressed spring extending between the first stop and a base of the cylinder, and a second stop fixed to the cylinder and engageable by the first stop under bias of the second spring. The first spring enables regulation of a number of revolutions of the vehicle engine, and the second spring, which has a larger pre-stress than the first spring and is less rigid than the first spring, is compressible to enable switching off of fuel feeding.

Claims

1. A servocylinder unit for adjusting an amount of fuel fed to a vehicle drive engine, said servocylinder unit comprising:

a cylinder having a longitudinal axis, a loading chamber at one end thereof, and a part immovably connected with said cylinder at the other end thereof;

a valve arrangement supplying a pressure medium from an injection pump to said piston;

a drive slippage governor connected with said valve arrangement and controlling said valve arrangement;

a piston displaceable in said cylinder under the action of the pressure medium and limiting said loading chamber in said cylinder;

pre-stressed spring means located between a gas pedal and the injection pump and on an opposite side of said piston from said loading chamber for biasing said piston to an initial position thereof and including;

a first spring acting on said piston for enabling regulation of a number of revolutions of the vehicle drive engine,

a first stop located in said cylinder for supporting said first spring and displaceable along the longitudinal axis of said cylinder,

a second spring extending between said first stop and said part of said cylinder and compressible to enable switching off of fuel feeding, and

a second stop fixed to said cylinder and engageble by said first stop under a biasing force of said second spring,

said second spring having a higher pre-stress than said first spring and a spring rigidity which is smaller than that of said first spring.

2. A servocylinder unit according to claim 1 wherein said first stop includes an annular member, said servocylinder unit includes a piston rod connected with said piston and extending through said annular member which encircles said piston rod with a clearance.

3. A servocylinder unit according to claim 2 wherein said cylinder has a first bore in which said piston is displaceable and a second bore of a greater diameter than said first bore and coaxial therewith, a shoulder formed as a result of a diameter difference of said first and second bores and forming said second stop.

4. A servocylinder unit according to claim 2 wherein said first stop further includes a bush extending from said annular member toward said piston for limiting compression of said first spring.