Piezoelectric injector for fuel-injection systems of internal combustion engines

Claim 2

A piezoelectric injector for fuel-injection systems of internal combustion engines, comprising: a piezoactuator guided under spring pretensioning in a valve housing, wherein an actuating part comprises a pressure pin that passes through the piezoactuator and a head part resting on the piezoactuator, said actuating part pressing a sealing piece against a valve seat thereby closing a bore leading to a pressure chamber, wherein the pressure pin and the piezoactuator are of approximately the same length and are made of similar thermal expansion characteristic ceramic material or ceramic-like material, and wherein the sealing piece can be lifted off its valve seat by the piezoactuator which is extended when in the charged state.

Claim 3

Piezoelectric injector according to claim 1, wherein the piezoactuator is composed of annular piezoelements in which the pressure pin of actuating part is concentrically located.

Claim 4

Piezoelectric injector according to claim 2, wherein the head part of the actuating part that rests on the piezoactuator and an upper lid-type closure of the valve housing form supporting bodies for a compression spring.

Claim 5

Piezoelectric injector according to claim 3, wherein a separate spacing washer is located between the lid-like closure and a spring end of the compression spring.

Claim 6

Piezoelectric injector according to claim 1, wherein piezoactuator abuts a lower housing surface of a narrowed housing part of the valve housing, and wherein the pressure pin of the actuating part ends flush with the piezoactuator in a vicinity of this lower housing surface when the sealing piece is in a closed position.

Claim 7

Piezoelectric injector according to claim 5, wherein sealing piece is designed as a valve ball that is secured in position in a recess in the pressure pin that is approximately hemispherical in shape.

Claim 8

Piezoelectric injector according to claim 6, wherein the head part of the actuating part that rests on the piezoactuator and an upper lid-type closure of the valve housing form supporting bodies for a compression spring.

Claim 9

Piezoelectric injector according to claim 7, wherein a separate spacing washer is located between the lid-like closure and a spring end of the compression spring.

Claim 10

Piezoelectric injector according to claim 5, wherein the head part of the actuating part that rests on the piezoactuator and an upper lid-type closure of the valve housing form supporting bodies for a compression spring.

Claim 11

Piezoelectric injector according to claim 9, wherein a separate spacing washer is located between the lid-like closure and a spring end of the compression spring.

Claim 12

Piezoelectric injector according to claim 1, wherein the head part of the actuating part that rests on the piezoactuator and an upper lid-type closure of the valve housing form supporting bodies for a compression spring.

Claim 13

Piezoelectric injector according to claim 11, wherein a separate spacing washer is located between the lid-like closure and a spring end of the compression spring.

Claim 14

A piezoelectric injector according to claim 1, wherein the valve housing comprises steel or aluminum.

Claim 15

Piezoelectric injector for fuel-injection systems of internal combustion engines, comprising: a piezoactuator guided under spring pretensioning in a valve housing, wherein the piezoactuator consists of two small actuators located side by side, wherein an actuating part comprises a pressure pin that extends between the actuators, with the pressure pin being coupled by a bridge that connects the two actuators, said actuating part pressing a sealing piece against a valve seat thereby closing a bore leading to a pressure chamber, wherein the pressure pin and the actuators are of approximately the same length and are made of similar thermal expansion characteristic ceramic material or ceramic-like material, and wherein the sealing piece can be lifted off its valve seat by the piezoactuator which is extended when in the charged state.

Claim 16

Piezoelectric injector for fuel-injection systems of internal combustion engines, comprising: a piezoactuator guided under spring pretensioning in a valve housing, wherein the piezoactuator consists of two small actuators located side by side, wherein an actuating part comprises a pressure pin that extends between the actuators, with the pressure pin being coupled by a bridge that connects the two actuators, said actuating part pressing a sealing piece against a valve seat thereby closing a bore leading to a pressure chamber, wherein the pressure pin and the actuators are of approximately the same length and are made of similar thermal expansion characteristic ceramic material or ceramic-like material, and wherein the sealing piece can be lifted off its valve seat by the piezoactuator which is extended when in the charged state.

Claim 17

Piezoelectric injector according to claim 14, wherein piezoactuator abuts a lower housing surface of a narrowed housing part of the valve housing, and wherein the pressure pin of the actuating part ends flush with the piezoactuator in a vicinity of this lower housing surface when the sealing piece is in a closed position.

Claim 18

Piezoelectric injector according to claim 15, wherein sealing piece is designed as a valve ball that is secured in position in a recess in the pressure pin that is approximately hemispherical in shape.

Claim 19

Piezoelectric injector according to claim 16, wherein the head part of the actuating part that rests on the piezoactuator and an upper lid-type closure of the valve housing form supporting bodies for a compression spring.

Claim 20

Piezoelectric injector according to claim 17, wherein a separate spacing washer is located between the lid-like closure and a spring end of the compression spring.

Claim 21

Piezoelectric injector according to claim 14, wherein the head part of the actuating part that rests on the piezoactuator and an upper lid-type closure of the valve housing form supporting bodies for a compression spring.

Claim 22

Piezoelectric injector according to claim 19, wherein a separate spacing washer is located between the lid-like closure and a spring end of the compression spring.