1. A matrix for use in the replication of a plastic element having a positive microstructure, comprising:
a first wear-resistant layer;
wherein said layer is supported by a carrier element and consists of an electrically conducting or semi-conducting material;
wherein said matrix is in the form of a singular structure mould cavity insert and is connected to a source of electrical heat energy via the first wear-resistant layer or a layer supporting the first wear-resistant layer by a connecting means;
wherein said carrier element acts as a heat insulator; and
wherein said carrier element has a thermal conductivity less than 2 Wm\xb0 K.
2. The matrix of claim 1, wherein the carrier element has a resistivity of less than 0.3 ohms\xd7mm2m.
3. The matrix of claim 1, wherein the carrier element has a resistivity of less than 0.03 ohms\xd7mm2m.
4. The matrix of claim 1, wherein the carrier element is capable of producing heat.
5. The matrix of claim 1, wherein the electrical heat energy is supplied by applying a voltage to the electrically conducting or semi-conducting material of the first wear-resistant layer.
6. The matrix of claim 1, wherein said carrier element comprises a polymer material that acts as a heat shield.
7. The matrix of claim 1, wherein said carrier element comprises a plastic composite.
8. The matrix of claim 1, wherein said first wear-resistant layer has a thickness ranging from about 1 to about 50 \u03bcm.
9. The matrix of claim 1, wherein said first wear-resistant layer is a metal layer.
10. The matrix of claim 1, wherein said first wear-resistant layer exposes an inverse microstructure on its surface having a depth variation ranging from about 0.1 to about 1000 \u03bcm.
11. The matrix of claim 1, wherein said carrier element comprises a polymer material that act as the heat insulator.
12. The matrix of claim 1, wherein said conducting or semi-conducting material has a resistivity of between 0.025 and 0.12 ohms\xd7mm2m.
13. A plastic element-producing machine, comprising:
a matrix, wherein said matrix comprising:
a first wear-resistant layer;
wherein said layer is supported by a carrier element and consists of an electrically conducting or semi-conducting material;
wherein said matrix is in the form of a singular structure mould cavity insert and is connected to a source of electrical heat energy via the first wear-resistant layer or a layer supporting the first wear-resistant layer by a connecting means;
wherein said carrier element acts as a heat insulator;
wherein said machine is a compression moulding, an injection moulding, or an embossing machine; and
wherein said carrier element has a thermal conductivity less than 2 Wm\xb0 K.
14. A method for the manufacture of a plastic element having a surface with a positive microstructure comprising the steps of:
(i) providing a matrix, wherein said matrix comprising:
a first wear-resistant layer;
wherein said layer is supported by a carrier element and consists of an electrically conducting or semi-conducting material;
wherein said matrix is in the form of a singular structure mould cavity insert and is connected to a source of electrical heat energy via the first wear-resistant layer or a layer supporting the first wear-resistant layer by a connecting means;
wherein said carrier element acts as a heat insulator;
wherein said carrier element has a thermal conductivity less than 2 Wm\xb0 K; and
(ii) replicating said plastic element on said matrix while supplying heat energy to the electrically conducting or semi-conducting material of the first wear-resistant layer during the filling of the matrix mould cavity with molten plastic.
15. The method of claim 13, wherein step (ii) is performed in a plastic element-producing machine based on replication of the matrix.
16. The method of claim 14, where said plastic element-producing machine is a compression moulding, an injection moulding or an embossing machine.
17. The method of claim 14, wherein said first wear layer is a metal layer.
18. The method of claim 14, wherein said plastic element is an optical disc.
19. A matrix for use in the replication of a plastic element having a positive microstructure, comprising:
a first wear-resistant layer;
wherein said layer is supported by a carrier element and consists of an electrically conducting or semi-conducting material;
wherein said matrix is in the form of a singular structure mould cavity insert and is connected to a source of electrical heat energy via the first wear-resistant layer or a layer supporting the first wear-resistant layer by a connecting means;
wherein said carrier element acts as a heat insulator; and wherein said carrier element comprises a plastic composite.
20. The matrix of claim 19, wherein the carrier element has a resistivity of less than 0.3 ohms\xd7mm2m.
21. The matrix of claim 19, wherein the carrier element has a resistivity of less than 0.03 ohms\xd7mm2m.
22. The matrix of claim 19, wherein the carrier element is capable of producing heat.
23. The matrix of claim 19, wherein the electrical heat energy is supplied by applying a voltage to the electrically conducting or semi-conducting material of the first wear-resistant layer.
24. The matrix of claim 19, wherein said first wear-resistant layer has a thickness ranging from about 1 to about 50 \u03bcm.
25. The matrix of claim 19, wherein said first wear-resistant layer is a metal layer.
26. The matrix of claim 19, wherein said first wear-resistant layer exposes an inverse microstructure on its surface having a depth variation ranging from about 0.1 to about 1000 \u03bcm.
27. The matrix of claim 19, wherein said conducting or semi-conducting material has a resistivity of between 0.025 and 0.12 ohms\xd7mm2m.
28. A plastic element-producing machine, comprising:
a matrix, wherein said matrix comprising:
a first wear-resistant layer;
wherein said layer is supported by a carrier element and consists of an electrically conducting or semi-conducting material;
wherein said matrix is in the form of a singular structure mould cavity insert and is connected to a source of electrical heat energy via the first wear-resistant layer or a layer supporting the first wear-resistant layer by a connecting means;
wherein said carrier element acts as a heat insulator; and
wherein said machine is a compression moulding, an injection moulding, or an embossing machine; and
wherein said carrier element comprises a plastic composite.
29. A method for the manufacture of a plastic element having a surface with a positive microstructure comprising the steps of:
(i) providing a matrix, wherein said matrix comprising:
a first wear-resistant layer;
wherein said layer is supported by a carrier element and consists of an electrically conducting or semi-conducting material;
wherein said matrix is in the form of a singular structure mould cavity insert and is connected to a source of electrical heat energy via the first wear-resistant layer or a layer supporting the first wear-resistant layer by a connecting means;
wherein said carrier element acts as a heat insulator;
wherein said carrier element comprises a plastic composite; and
(ii) replicating said plastic element on said matrix while supplying heat energy to the electrically conducting or semi-conducting material of the first wear-resistant layer during the filling of the matrix mould cavity with molten plastic.
30. The method of claim 29, wherein step (ii) is performed in a plastic element-producing machine based on replication of the matrix.
31. The method of claim 30, where said plastic element-producing machine is a compression moulding, an injection moulding or an embossing machine.
32. The method of claim 30, wherein said first wear layer is a metal layer.
33. The method of claim 30, wherein said plastic element is an optical disc.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A pneumatic brake booster for a motor vehicle, comprising a piston (22) mounted between a control rod (24) and a push rod (34), the control rod being terminated by a distributor plunger (28) guided translationally in a housing (48) of the piston, and a three-way valve (30) mounted in the piston (22) around the control rod (24) and comprising a shutter (56) engaging with a seat of the piston (22) and with a seat (70) of the distributor plunger (28), a cylindrical sleeve (46) mounted in an axially sliding manner in said housing (48) around the distributor plunger (28), and means (52) which permanently urge the sleeve (46) elastically toward the shutter (56) of the three-way valve in order to move said shutter away from a seat (70) on the distributor plunger (28) and to increase the supply of atmospheric air to a working chamber (16) of the booster, means (58, 58\u2032) for axially locking the sleeve (46) when the shutter (56) is in a moved-away position, and means (66) for unlocking the sleeve which are sensitive to the speed of movement of the control rod (24) and of the distributor plunger (28) in the direction of braking and which unlock the sleeve (46) when this speed is at least equal to a predetermined value, characterized in that the means for axially locking the sleeve (46) are arranged in the housing (48) of the piston between the distributor plunger (28) and the piston (22) and comprise an elastically deformable element (58, 58\u2032) for retaining the sleeve (46), said element (58, 58\u2032) being mounted in an annular groove or slot in the body (42) of the piston (22).
2. The booster according to claim 1, characterized in that a part (64) of the retaining element (58) bears on a ramp or oblique surface (66) of the distributor plunger (28) so that it can be moved away from said plunger and release the sleeve (46) when the distributor plunger (28) is moved axially toward the push rod (34) with respect to the piston (22).
3. The booster according to claim 1, characterized in that the retaining element (58) is formed by a spring steel wire stirrup comprising at least one kink housed in said groove in the housing (48) of the piston and at least one kink (62) housed in a notch or slot in the sleeve (46).
4. The booster according to claim 3, characterized in that the retaining element (58) comprises at least two opposed kinks (62) housed in notches or slots in the sleeve (46).
5. The booster according to claim 4, characterized in that the sleeve (46) is able to slide axially in a sealed manner in the housing (48) of the piston (22).
6. The booster according to claim 5, characterized in that the sleeve end rim (54) intended to be applied against the shutter (56) forms a sealing seat for the shutter.
7. The booster according to claim 6, characterized in that the retaining element (58) limits the axial movement of the sleeve (46) toward the shutter (56) of the three-way valve.
8. The booster according to claim 7, characterized in that it comprises means (72) borne by the piston (22) to limit the axial movement of the distributor plunger (28) with respect to the piston (22) toward the shutter (56) of the three-way valve and to define a rest position for the distributor plunger (28).
9. The booster according to claim 8, characterized in that said movement-limiting means comprise a rod or a clip (72) engaged in openings (74, 76) in the cylindrical walls of the piston (22) and in the sleeve (46) and are able to move axially over a limited travel with respect to the piston (22).
10. The booster according to claim 9, characterized in that said movement-limiting means (72) also form means for returning the sleeve (46 ) to an axial-locking position in the housing (48) of the piston, in which the sleeve (46) is moved away from the annular shutter (56) of the three-way valve.
11. The booster according to claim 10, characterized in that the means (72) for limiting the movement and for defining a rest position for the distributor plunger (28) are substantially in the same transverse plane as the means (58\u2032) for axially locking the sleeve (46).
12. The booster according to claim 11, characterized in that the means (72) for limiting movement and for defining a rest position for the distributor plunger (28) and the means (58\u2032) for axially locking the sleeve (46) are mounted by elastic snap-fastening on the body (42) of the piston.
13. The booster according to claim 12, characterized in that a washer (80, 86, 94) is interposed with an axial clearance between the end of the distributor plunger (28) and a reaction disk (40) mounted between the piston (22) and the push rod (34), this washer (80, 86, 94) being housed in a recess (82) in the end of the piston (22) and being applied against the bottom of this recess in order to transmit a reaction force while the distributor plunger (28) is returning to a rest position or non-braking position.
14. The booster according to claim 13, characterized in that the washer (80) is a flat washer and transmits a reaction force to the piston (22).
15. The booster according to claim 13, characterized in that the washer (86) is guided in axial translation in a ring (88) guided in axial translation in the recess (82), the ring having an axial length which is greater than that of the washer, and the washer (86) transmits a reaction force to the distributor plunger (28).
16. The booster according to claim 13, characterized in that the washer (94) comprises an axial cylindrical tail (96) which transmits a reaction force to the distributor plunger (28).