Electricity: motive power systems – Automatic and/or with time-delay means
Reexamination Certificate
2002-09-13
2004-02-10
Masih, Karen (Department: 2837)
Electricity: motive power systems
Automatic and/or with time-delay means
C318S727000, C318S729000, C318S808000
Reexamination Certificate
active
06690132
ABSTRACT:
The invention relates to an assembly for adjusting mobile elements of furniture, with a motor displaying a first and a second connection, a control circuit for controlling the motor, which is provided with at least a first push-button switch for controlling the motor, a power supply circuit with an operating voltage output, with a mains connection located between a mains plug that can be connected to an alternating-current mains and the power supply circuit, with a relay displaying a relay switch and a control input controlling the relay switch, where the relay switch is located in the mains connection and is in OFF position when unexcited, and with an auxiliary power source that can be connected to the control input of the relay.
An assembly of the kind mentioned above is known from European Patent Specification 0 615 667 B1. The assembly described therein for safety isolation of control devices from the mains refers to an assembly for adjusting mobile elements of furniture that is provided with two motors. One motor displays a first and a second connection. Furthermore, a control circuit comprising a first and a second push-button switch is provided for each motor. The control circuit of a motor also includes a first and a second relay. The relay coil of the first relay is connected to operating potential via the first push-button switch and the relay coil of the second relay via the second push-button switch. The relay switches of both relays are designed as changeover switches, where one changeover contact is connected to the operating voltage output of the one polarity and the other changeover contact with the operating voltage output of the other polarity. The centre contact of the relay switch of the first relay is connected to the first connection of the motor and the centre contact of the relay switch of the second relay to the second connection of the motor. In unexcited state, the relay switches each establish a connection between their centre contact and the operating voltage output with the same polarity as on the respective other relay switch.
In this known assembly, the operating voltage source is designed as a direct-current source and each motor as a direct-current motor. As a result, the design of the control circuit provides control of the direction of the motors. If, for example, the first push-button switch is operated, the first relay picks up and switches over the relay switch. While the first and second connection of the motor had the same potential up to that time, the switching operation now connects the first connection to the other operating voltage potential. The motor thereupon performs motion in one direction until the first push-button switch is released. If the second push-button switch is subsequently operated, the second relay picks up, thereby reversing the polarity on the motor and causing the motor to move in the other direction.
In this known assembly, there is also a third relay with a relay switch located in the mains lead to the power supply circuit. An auxiliary power source is connected in parallel to the operating voltage output of the power supply circuit. This auxiliary power source is connected to the control input of the third relay via each of the push-button switches.
Since the relay switch of the third relay is in OFF position when unexcited, the power supply circuit is initially isolated from the mains. If one of the push-button switches is now operated, the voltage of the auxiliary power source is applied to the control input of the third relay via the push-button. This relay picks up as a result and switches its relay switch to the ON position. The power supply circuit is thereby connected to the mains voltage and supplies an operating voltage at its operating-voltage output. As a result, each of the relays forming part of the control circuit can pick up, provided the associated push-button switch is pressed. The motor thereupon performs its adjusting motion. The third relay remains operational during this time, since its control input is now supplied with operating voltage. If the push-button switch is released, for instance because the necessary adjusting motion has been completed, the relay associated with the respective push-button drops off, as does the third relay, and the circuit arrangement is once again isolated from the mains.
The disadvantage of this arrangement is that each push-button switch has to be provided with a relay, meaning that the circuit arrangement not only requires a considerable amount of space, but is also complex and expensive to manufacture.
Consequently, the object of the invention is to disclose an assembly for adjusting mobile elements of furniture that can be constructed more easily and cost-effectively while maintaining safety isolation from the mains, i.e. isolation from the mains during times when no control functions have to be executed and connection to the mains when control commands are received.
According to the invention, this object is solved in that the first push-button switch forms an electric circuit with the motor and the operating voltage output. Moreover, either the control input of the mains isolating relay is connected in parallel to the motor, or a rectifier bridge known as a Graetz bridge is connected between the motor and the control input of the mains isolating relay. A rectifier bridge of this kind is provided with four diodes, of which two first diodes have their cathodes interconnected in a positive node, while their anodes are each interconnected with the cathodes of the two second diodes in an alternating-current node. In this context, the first and second connections of the motor are each connected to an alternating-current node. The positive and negative nodes are each connected to the control input of the mains isolating relay.
The first alternative provides for the simplest realisation of the solution according to the invention, where both the motor and the mains isolating relay are connected directly by the first push-button. In this context, the relay switch of the mains isolating relay is in OFF position when in quiescent state. Consequently, the power supply circuit is not connected to the mains. If the first push-button is pressed in order to start the motor, the voltage from the auxiliary power source is applied via the first push-button switch to the mains isolating relay, which picks up and connects the power supply circuit to the mains. Operating voltage is then present at the operating-voltage output and the mains isolating relay is held in picked-up state by the operating voltage for as long as the first push-button switch is pressed. When it is released, the voltage at the control input of the mains isolating relay is interrupted and this mains isolating relay drops off. The power supply circuit is then no longer connected to the mains, since the relay switch of the mains isolating relay is once again in OFF position.
The second alternative of the solution according to the invention displays the same mode of operation. When the push-button switch is pressed, the voltage from the auxiliary power source is applied to the control input of the mains isolating relay via the rectifier bridge, causing the mains isolating relay to pick up and connect the power supply circuit to the mains for as long as the push-button switch is pressed. However, interconnection of the rectifier bridge avoids feedback from the control input of the mains isolating relay to the motor connections. This permits the use of several motors, for example, all of which operate with one mains isolating relay, as described in more detail below.
In one embodiment of the invention, provision is made for the operating-voltage output to be designed as a DC output and the motor as a DC motor.
Designing the invention with DC motors offers not only favourable torque distribution, but also the advantage of simple control of the sense of rotation of the motors.
Especially for simple control of the sense of rotation of the DC motors, a further embodiment of the invention provides for the incl
Grossman Tucker Perreault & Pfleger PLLC
Masih Karen
OKIN Gesellschaft fur Antriebstechnik mbH & Co. KG
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