Electrical Door Actuator

Field of the Invention

[001] The present invention relates, in general, to an electric actuator and, more specifically, to an electric actuator for opening and closing the door to a vehicle, more particularly, bi-fold or swing doors of a mass transit vehicle such as buses or vans.

Background

[002] Prior to the use of power operated door openers, doors of mass transit vehicles were manually opened and closed, typically by the vehicle operator. The strain of actuating these door openings and closings often led to long term medical difficulties for the vehicle operators. Power door actuators have been developed to reduce the strain on vehicle operators caused by the repeated opening and closing of vehicle doors. The need for power operated door openers led to the development of largely pneumatically actuated operators since in most large vehicles, use of air brake systems provides a reliable and convenient source of operating air at controlled pressures.

[003] However, many of the vehicles typically incorporate hydraulic brake systems. Therefore, no air supply is available, and hydraulic door drives are high in cost and involve excessive maintenance in order to prevent leaks and loss of brake system integrity. A growing need for a reliable low cost electric bus door actuator existed.

[004] Electric door actuators have also been developed, motorized actutors are widely used for controlling the movement of swing doors by remote or automatic control. Typically, swing door actuators include an electric motor driving an output shaft through a reduction gear drive for controlling movement of the door between a closed position and an open position, the actuator also including a return spring or the like for at least assisting the motor to move the door to the closed position. Several types of swing door actuator mechanisms have been developed but prior art actuators tend to be mechanically complicated, particularly if adapted for so called universal applications, that is, applications where the actuator may be reversed in its working position for swinging doors of opposite "hands" or for controlling doors to swing inwardly or outwardly with respect to the actuator, and/or the door frame. Further, the prior art systems fail to efficiently use space and require motion in more than one plane of action.

[005] Power door actuators usually include an emergency release mechanism. A pre-existing design for the release mechanism is a toggle-based device.

[006] Therefore, a need exists for an electric door actuator that maximizes space efficiency, while also ensuring that all motion occurs in a single plane. There is also a need for an actuator with a simple emergency release mechanism that is space and cost efficient.

[007] Also, it is desirable to provide a bi-fold / swing door actuator with low maintenance requirements, and which may be easily adapted for controlling doors in inswing and outswing applications and where the actuator remains reliable for a long life. It is to these ends that the present invention has been developed.

Objects of the Invention

[008] It is, therefore, an object of the invention to provide a compact, easily maintained, low cost, electrically driven power door actuator primarily for multi-passenger utility transport vehicles such as buses and vans.

[009] It is also an object of the invention to combine innovative electrical and mechanical components to precisely open and close passenger doors without consuming much power.

[0010] It is a further object of this invention to provide an electrically driven door actuator for multi-passenger vehicles having electronic controller for complete motion control and adjustable individual door panel phasing during opening and closing sequences.

[0011] It is a further object of this invention to provide an electric drive door actuator for multi-passenger vehicles wherein the forces holding the doors closed is easily adjustable.

[0012] It is yet an additional object of this invention to provide an electrical drive door actuator for multi-passenger vehicles with improved emergency features with better obstruction sensing in both door opening and closing operations.

Summary of the Invention

[0013] The present invention provides an improved bi-fold / swing door actuator including a mechanism operable for returning the door from an open position to a closed position regardless of the hand or swing direction of the door.

[0014] Briefly, according to this invention, there is provided an electrically driven door actuation system consisting of electrical, electronic and mechanical parts which are integrated together to achieve the accurate opening and closing of the bus door or any type of institutional doors in common.
[0015] The highly precise electrical Bi-fold / Swing door actuator operates using a 12 v power supply.

[0016] The electrically driven door actuation system as provided includes a gear box (32), a linkage assembly (310), a general frame, a DC motor (33), stopper switch (35)> micro limit switch (39) and an electronic controller. The general frame of the actuator further comprises of a base plate (37), outer cover, mounting pads etc. The configuration of each of the above elements has been arranged for maximum space efficiency and to ensure that all motion occurs in a single plane of action. This allows the system to reduce inefficiency of operation, leading to a lower operational heat build-up, and reduced stress and strain on both the actuator mechanism and the vehicle frame.

[0017] In accordance with one aspect of the present invention a motorized swing door actuator is provided which includes a frame which may be mounted on a support member for controlling doors of one hand or the other without major modifications to the actuator. The actuator is characterized by a frame which supports an electric drive motor (33) driving an output shaft (413) through a reduction gear drive wherein the output shaft (413) of the operator is drivingly connected to a return spring. The mechanism is mechanically uncomplicated and provides for use of the actuator for controlling doors of opposite hand or swing direction when moving from a closed position to an open position and back to a closed position.

[0018] In accordance with another aspect of the present invention a motorized swing door actuator is provided which comprises a frame for supporting a gear drive mechanism, a drive motor (33), a return spring and a mechanism for storing energy in the spring and returning the spring energy to the actuator for moving the door in one direction or the other. The frame may be conveniently mounted on a support plate in two opposed positions, depending on the door to be operated.

[0019] The present invention also provides a swing door operator which is mechanically uncomplicated, compact, reliable in operation and easily modified as to its working position for controlling an inswing door, an outswing door, and for controlling a door regardless of the direction of swing movement or so-called hand of the door.

[0020] Those skilled in the art will further appreciate the advantages and superior features of the invention as well as other important aspects thereof upon reading the detailed description which follows in conjunction with the drawings.

Brief Description of Invention

[0021] Further features and other objects and advantages will become apparent from the following detailed description made with reference to the drawings in which:

[0022] FIG. 1 is a perspective view of an electrically-driven door actuation system according to this invention;

[0023] FIG. 2 is a top view of an electrically-driven door actuation system according to this invention;

[0024] FIG. 3 is an exploded perspective view of an electrically-driven door actuation system according to this invention as shown in FIG. 1; and

[0025] FIG. 4 is an exploded perspective view of the gear box (32) assembly as shown in FIG. 3.

Detailed Description of Invention

[0026] The following background information is provided to assist the reader to understand the environment in which the invention will typically be used. The terms used herein are not intended to be limited to any particular narrow interpretation unless specifically stated otherwise in this document.
[0027] The preferred embodiment of the invention comprises of a gear box (32), a linkage assembly (310), a general frame, a DC motor (33), stopper switch (35), micro limit switch (39) and an electronic controller. The general frame of the actuator further comprises of a base plate (37), outer cover, mounting pads, fasteners etc. Each component of the preferred embodiment is explained below in detail.
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[0028] The mechanical parts comprising of gear box (32) housing which encloses the gears through which the torque is transmitted. It further comprises of a driving shaft and driven shaft, the transmitting gear, drive connector (414) to transmit the power, springs to maintain the spring tension in the necessary parts. Also the provision to switch between auto and manual operation of the actuator is provided in the gear box (32) of the actuator which contains the auto manual hand lever connected to the cam (38) shaft which is interconnected to the rack shaft (412) to switch between auto and manual options. The manual actuation mechanism could become necessary in emergency situations.

[0029] The linkage assembly (310) of the mechanical parts consists of the linkage which connects the door to the unit making it possible for the unit to achieve the opening and closing operation of the door. The linkage is connected to the output shaft (413) of the gear box (32) using simple mechanism thus integrating it to the unit. The linkage acts as the coupler between the actuator and the door transmitting the power from gearbox.

[0030] The general frame of the actuator comprises of the base plate (37), outer cover, mounting pads, fasteners, and the rest of the mechanical components. The base plate (37) gives the skeletal structure to the actuator. It contains and integrates all the components of the actuator regardless of the electrical, electronic or mechanical parts, base plate (37) gives the shape to the actuator and ensures the rigidity of the actuator. The various components of the actuator are placed together and fastened or assembled on the base plate (37).

[0031] The High torque low voltage motor (33) drives the electrical Bi-fold / Swing door actuator. The 12v. 2Amps DC motor rotating at 5500 RPM is the

heart of the actuator which drives the actuator. The DC motor (33] is coupled to the gear box (32) through a drive connector (414] thus transmitting power to the mechanical components and thus driving the Bi-fold / Swing door actuator.

[0032] The actuator consists of two types of switches. One is stopper switch (35] and the other one is Micro limit switch (39). To start with, the stopper switch (35) ensures the safety of operation of the Bi-fold / Swing door actuator which is triggered by the stopper plate which is connected with spring loaded rack shaft (412). The micro limit switch (39) is used to read the end positions of the door, which may either be fully open or close. The end position of the door is fed to the controller through the micro switch with the help of the cam (38) which is being linked to the linkage assembly (310).

[0033] The electronic controller of the Bi-fold / Swing door actuator serves as the brain of the actuator. The controller is interlinked with all the other electrical and electronic items in the actuator. When the driver gives the signal for the door open or door close the signal are fed to the controller through a toggle switch which is used by the driver to open and close the door of the vehicle. The controller receives the signal through the toggle switch which is operated by the driver and the signals are processed by the controller and the feedback is fed to the motor (33) and the forward and reverse or open and close operation of the door is achieved by on the door.

[0034] When the driver gives the close command the signals are sent to the controller and the controller gives a signal which drives the motor (33) in the forward motion and when the driver gives the open command the vice versa occurs in the reverse direction, by changing the polarity of the motor (33) the open and close function of the actuator is achieved.

[0035] The limit switches (39) connected to the controller helps in reading the full open and close positions of the door. The limit switches (39) which are actuated by the mechanical cam (38) gives the open and close position of the door connected to the actuator.

[0036] In an embodiment, when the controller receives the input signal from the limit switch (39) for fully open position the electronic controller gives the feedback signal to the motor (33) and stops the power supply to the motor (33) so that motor (33) doesn't run further thereby protecting the overload to the motor (33) and also ensures that there is no power wastage during the idle time when the actuator is not in function. Similarly, the operations of motor (33) is terminated when the door reaches the fully closed position.

[0037] The stopper switches (35) which are designed for the safety purpose of the actuator make sure that the actuator stops working when the door attains the full closed or full open position. When the door attains the full closed or full open position and if it is not read by the micro limit switch (39) then the stopper switch (35) comes to play, in these cases the rack shaft (412) connected to the ring gear (416) is driven which in turn pushes the stopper plate and hits the stopper switch (35) therefore stopping the power supply to the motor (33) protecting the motor (33) and circuit from overload.

[0038] In an embodiment, an LED light is connected to the controller which gives a visual signal of door close and door open. In another embodiment, the buzzer connected to the electrical controller gives a caution signal 3 seconds before closing and opening of the door so that the passengers standing nearby the door are alerted that the door is going to open or close so that they can step away from the doorway and are not hurt by the door.

[0039] The electrical controller and the entire circuit is connected to an electrical circuit breaker (36) which protects the actuator from electrical overload. The electrical controller also has an inbuilt safety feature, which stops the closing of the door if there is any obstacle in the doorway, for example, if a passenger is stuck in the doorway and driver gives a close command without noticing the passenger, the door starts closing and when the door comes in contact with the passenger the motor [33) gets overload and the current in the motor (33) increases and that overload or increase in current in the motor (33) is sensed by the electrical controller and a feedback signal is given to the motor (33) to stop the closing operation of the door thus ensuring the safety of the passenger.

[0040] In an exemplary embodiment of the invention, when the driver gives the signal for closing the door, the signals are sent to the actuator. The electrical controller in the unit receives the signal and sends a feedback signal to the motor (33) and the motor (33) drives the worm shaft (48) which in turn drives the worm wheel having sun gear (44) in the centre of the worm wheel (45) which drives the planetary gear (415) arrangement which is integrated with the output shaft (413) projecting out of the output shaft (413) housing. The power is transmitted through the linkage which is pivoted to the door and hence the door closes. The cam (38) connected to the linkage also rotates when the linkage moves, which in turn activates the micro limit switch (39) when the door reaches the fully closed position. Similarly when the door reaches the fully opened position the micro switch gives signal to the Electronic controller regarding the fully open position, and hence the controller sends signal to the motor (33) and the motor (33) stops avoiding any overload to the motor (33) hence increasing the life of both motor (33) and the controller. Thus the smooth operation in opening and closing of the door is ensured by the actuator.

[0041] In yet another exemplary embodiment of the invention, in case of emergency, for example, when a passenger is held in the doorway and the driver gives close command by mistake, the door starts closing and when the door comes in contact with the passenger the full close position is not sensed by the micro limit switch (39). Hence, the motor (33) would not stop leading to increase in load and therefore increase in current of motor (33) which is sensed by the electrical controller and a feedback signal is given to the motor (33) to stop the closing operation of the door thus preventing the passenger from getting hurt.

[0042] It is apparent that there has been provided in accordance with the invention an electrically driven door actuator, that fully satisfies the objects, aims, and advantages as set forth above. While the operator disclosed has been described in conjunction with a specific embodiment, it is evident that many alternatives, modifications, and variations will be apparent to those skilled in the art in light of the foregoing description.

[0043] The invention has been described in such full, clear, concise and exact terms so as to enable any person skilled in the art to which it pertains to make and use the same. Persons who possess such skill will also recognize that the foregoing description is merely illustrative and not intended to limit any of the ensuing claims to any particular narrow interpretation. Accordingly, it is intended to embrace all such alternatives, modifications, and variations as may fall within the spirit and broad scope of the appended claims.

ClaimS

1. An electrical door actuator for opening or closing passenger door in transit vehicles comprising:
a gear box (32), enclosing the gears through which the torque is transmitted
a linkage assembly (310), connecting the door to the actuator unit
a general frame, ensures rigidity of the actuator
a DC motor (33), high torque low voltage motor (33) to drive the actuator; and
an electronic controller, interlinked with all electrical and electronic components of the actuator
2. An electrical door actuator for opening or closing passenger door in transit vehicles wherein the gear box (32) further comprises of:
a driving shaft and a driven shaft,
the transmitting gear,
drive connector (414) to transmit the power,
springs to maintain the spring tension

3. An electrical door actuator for opening or closing passenger door in transit vehicles wherein the general frame of the actuator further comprises
of:
a base plate (37), giving a skeletal structure and rigidity to the actuator, integrating electrical, electronic and mechanical components; outer cover, mounting pads

4. An electrical door actuator for opening or closing passenger door in transit vehicles as claimed in claim 1 characterized by a stopper switch (35) which ensures safety on being triggered by a stopper plate connected with spring loaded rack shaft (412).
5. An electrical door actuator for opening or closing passenger door in transit vehicles as claimed in claim 1 characterized by a micro limit switch (39) utilized to read the end positions of the door during opening or closing.

6. An electrical door actuator for opening or closing passenger door in transit vehicles as claimed in claim 1 characterized by an electronic controller which is interlinked with the electrical and electronic components of the actuator

7. An electrical door actuator for opening or closing passenger door in transit vehicles as claimed in claim 1 wherein electrical controller and the entire circuit is connected to^an electrical circuit breaker (36) which protects the actuator from electrical overload.

8. A method of operating the electrical door actuator, the method comprising:
a. signalling for opening or closing of the door through the toggle switch;
b. feeding of the toggle switch signal into the electronic controller;
c. processing of signal data by the electronic controller;
d. feeding of the data into the motor (33) by the electronic controller for
forward or reverse operation corresponding to closing or opening of the door;

e. reading of the end position of the door by the limit switch (39) which further input said data to the electronic controller for signalling the motor (33) to stop

9. The method as claimed in claim 8, wherein if the micro limit switch (39) does not read the end position, the rack shaft (412) connected to the ring gear (416) is driven which in turn pushes the stopper plate and hits the stopper switch (35) therefore stopping the power supply to the motor (33) protecting the motor (33) and circuit from overload

10. The method as claimed in claim 8, wherein an obstacle in the doorway which does not allow the door to close will not trigger the micro limit switch (39) and therefore the motor (33) will keep running leading to motor (33) overload which is sensed by the electronic controller signalling the motor (33) to stop.