1. A device (10) for the incremental control of at least a first direct-current motor (12) for a cooling fan of a motor vehicle with a first current-limiting component (14) and a second current-limiting component (16), and a first (22), second (24) and third switching element (28),
wherein
the switching elements (22, 24, 28) connect the first (14) and second current-limiting components (16) in a manner such that the cooling capacity of the cooling fan can be varied in at least four non-zero levels.
2. The device as recited in claim 1,
wherein
the first current-limiting component (14) and second current-limiting component (16) can be operated individually or in a series connection or a parallel connection.
3. The device as recited in claim 1,
wherein
the first current-limiting component (14) can be connected to a supply voltage (Vcc) using the first switching element (22), and to a first contact (26) of the direct-current motor (12) using the second switching element (24),
the second current-limiting component (16) can be connected to the supply voltage (Vcc) using the third switching element (28), and to the first contact (26) of the direct-current motor (12) using the second switching element (24),
the first current-limiting component (14) and second current-limiting component (16) can be connected in parallel to the supply voltage (Vcc) using the first switching element (22) and the third switching element (28), and
they can be connected to the first contact (26) of the direct-current motor (12) using the second switching element (24), and
the first current-limiting component (14) and second current-limiting component (16) can be connected in series to the supply voltage (Vcc) and to the first contact (26) of the direct-current motor (12) using the first switching element (22) and the second switching element (24).
4. The device as recited in claim 1,
wherein
the first current-limiting component (14) is a first resistor (18), and the second current-limiting component (16) is a second resistor (20).
5. The device as recited in claim 4,
wherein
the first resistor (18) has a first resistance value R1, and the second resistor (20) has a second resistance value R2, and a first quotient,
Q
1
=
R
1
R
1
+
R
2
which is calculated based on first resistance value R1 and second resistance value R2, is located approximately in a range between 50% and 100%.
6. The device as recited in claim 5,
wherein
the first quotient Q1 is approximately 62%.
7. The device as recited in claim 4,
wherein
the at least one direct-current motor (12) has a motor resistance value Rm, and a second quotient,
Q
2
=
R
1
+
R
2
R
m
which is calculated based on first resistance value R1, second resistance value R2, and motor resistance value Rm, is located approximately in a range from 1 to 10.
8. The device as recited in claim 1,
wherein
the first current-limiting component (14) is a resistor (46), and the second current-limiting component (16) is a second direct-current motor (48).
9. The device as recited in claim 8,
wherein
the first direct-current motor (12) and second direct-current motor (48) can be operated individually or in a series connection or a parallel connection.
10. The device as recited in claim 8, wherein
a first contact (26) of the first direct-current motor (12) can be connected to a supply voltage (Vcc) using the first switching element (22) and second switching element (24) via the resistor (46),
the first contact (26) of the first direct-current motor (12) can be connected to a second contact (32) of the first direct-current motor (12) using the second switching element (24) and the third switching element (28),
a first contact (50) of the second direct-current motor (48) can be connected to the supply voltage (Vcc) using the first switching element (22) via the resistor (46), and a second contact (52) of the second direct-current motor (48) can be connected to the second contact (32) of the first direct-current motor (12) using the third switching element (28),
the first direct-current motor (12) and second direct-current motor (48) can be connected in series or parallel using the second switching element (24) and third switching element (28).
11. The device as recited in claim 8,
wherein
the resistor (46) has a resistance value R\u22480 ohm.
12. The device as recited in claim 1,
wherein
a thermal protective element (70) is assigned to at least one switching element (22, 24, 28).
13. The device as recited in claim 1,
wherein
the switching elements (22, 24, 28) are designed as a relay (60) andor MOSFET andor FET andor bipolar transistors.
14. The device as recited in claim 1,
wherein
a fourth switching element (56) is connected in parallel with the at least one direct-current motor (12, 48).
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. Hydraulic actuator comprising
a hollow body (1, 3) defining a cylindrical cavity;
a rod (5) which is mounted so as to be able to slide within the body along a sliding axis between two end positions and which is integral with a piston sliding in a sealed manner within the cylindrical cavity of the body in order to define two chambers (C1, C2) therein; the rod defining an interior passage connecting the two chambers, this passage being equipped with a valve (20) comprising a shut-off member (21) which is returned towards a seat (22) and which engages with the latter to close the passage, the rod receiving a push member (15, 26) which can move relative to the rod between a position in which it is moved apart from the shut-off member (21) of the valve and a position in which it forces the shut-off member to open, the push member being constrained in the latter position when the rod reaches the end of its stroke in one of its end positions as a result of the push member engaging with a portion (3) of the hollow body,
characterized in that the push member (15, 26) comprises a needle (26) which is mounted so as to be able to slide within the rod in a direction parallel to the sliding axis of the rod, the needle having a distal end close to the valve and a proximal end close to a crosspiece (15) which is floatingly mounted across the rod in a longitudinal slot (13) therein so as to project to either side of the rod such that, when the rod reaches the end of its stroke, ends of the crosspiece will bear against the facing portion (3) of the hollow body, pushing the crosspiece relative to the needle such that said crosspiece in turn pushes the needle, which in turn pushes the shut-off member of the valve to force it to open.
2. Actuator according to claim 1, wherein the push member (15, 26) comprises a needle (26) which is mounted so as to be able to slide within the rod in a direction parallel to the sliding axis of the rod, the needle having a distal end close to the valve and a proximal end close to a crosspiece (15) which is floatingly mounted across the rod in a longitudinal slot (13) therein so as to project to either side of the rod such that, when the rod reaches the end of its stroke, ends of the crosspiece will bear against the facing portion (3) of the hollow body, pushing the crosspiece relative to the needle such that said crosspiece in turn pushes the needle, which in turn pushes the shut-off member of the valve to force it to open.