Plunger assembly having a preset spring force pre-load

• US 20020026827A1
• Filed: 08/14/2001
• Published: 03/07/2002
• Est. Priority Date: 02/28/2000
• Status: Active Grant

• Current Assignee: Delphi Technologies, Inc. (BorgWarner Incorporated)
• Original Assignee: Delphi Technologies, Inc. (BorgWarner Incorporated)
• Inventors: Morales, Veronica, Gomez, Javier, Heinrichs, Jeffrey Alan, Fong, Keith B., Rocha, Omar
• Granted Patent: US 6,668,639 B2
• Time in Patent Office: Days
• US Class Current: 73/161
• CPC Class Codes: F16K 31/046 with electric means, e.g. electric switches, to control the motor or to control a clutch between the valve and the motor F16K31/041 takes precedence
• CPC Class Codes: F16K 31/0665 with valve member being at least partially ball-shaped F16K31/0662 takes precedence

Abstract

A uniformly preset spring force pre-load among a number of identical solenoid actuated valve assemblies (28) by uniquely adjusting the spring pocket length (L) of each respective plunger (12) to accommodate a respective spring (20) which is uniquely mated thereto. This adjustment is accomplished using a two-component plunger (12) consisting of a plunger body (14) having a central bore (22) and a rod (18) sidably located within the central bore. The rod (18) is press-fit into the central bore (22), and the spring pocket includes a portion of the central bore unoccupied by the rod. By pressing the rod (18) a selected distance into the central bore (22), a precisely set spring pocket is obtained which is uniquely correct for a selected spring (20), in that the selected spring is compressed to a precisely preset spring force pre-load. The adjusted plunger (12) and spring (20) are uniquely assigned to each other to collectively form a customized plunger assembly (10) having a preset spring force pre-load, whereupon a valve assembly (28) is manufacturable therewith having the precisely preset spring force pre-load. In carrying-out the adjustment of the plunger (12) with respect to a specific spring (20), the rod is pressed into the bore by a controllable source of force, such as for example provided by a stepper motor (88), and the spring force pre-load is monitored by a load cell (78) to ascertain when the desired spring force pre-load is achieved. Monitoring and force control is preferably automatic via a micro-controller (98), but may be manual.

Claims

1. A method for providing a uniformly preset spring force pre-load among a number of plunger assemblies, wherein each plunger assembly comprises a plunger and a spring mated therewith, wherein the plunger includes a plunger body having a central bore and a rod partially received in the central bore, wherein a spring pocket is defined between a rod end located within the central bore and an abutment location spaced from the rod end, the spring being located in the spring pocket, and wherein the preset spring force pre-load is defined by compression of the spring between the rod end and the abutment location, said method comprising the steps of:

providing a plunger by placing a predetermined portion of a rod within a central bore of a plunger body, wherein a rod end of the rod enters into the central bore from a forward end of the plunger body;

selecting a particular spring for being uniquely mated with the plunger;

placing the spring into an open end of the central bore, wherein the spring enters into the central bore from a rearward end of the plunger body so that a first end of the spring abuts the rod end;

placing an abutment against a second end of the spring, wherein the abutment is located in substantially fixed relation to the rearward end of the plunger body;

sliding the rod relative to the plunger body to thereby compress the spring between the rod end and the abutment until compression force of the spring equals a present spring force pre-load.

2. The method of claim 1, wherein said steps of placing an abutment and sliding the rod further comprise:

placing the plunger a predetermined distance into a cavity;

preventing the rod from moving further into the cavity;

placing a face of a ram against the rearward end of the plunger body, wherein the abutment is slidably mounted relative to the ram;

connecting a load cell to the abutment; and

applying a force to the ram to thereby cause the plunger body to move relative to the rod;

wherein the load cell measures compression force of the spring during said step of applying a force and provides an output signal responsive thereto, and wherein said step of applying a force is terminated responsive to the output signal.

3. The method of claim 2, wherein said step of applying a force is manually controlled responsive to an operator monitoring the output signal.

4. The method of claim 2, wherein said step of applying a force is automatically controlled responsive to micro-controller monitoring the output signal.