This invention relates to a pneumatically controlled door assembly for closing and opening the door of a compartment, exemplified by (but not restricted to) the engine compartment provided at the rear (tail) of a three wheeler motor vehicle, popularly called the auto rickshaw. For the sake of clarity and brevity it is with reference to this engine compartment that the following description will be given, although, as already stated, this invention will be applicable to other compartments intended for different purposes as well.

In the known art in a three-wheeler vehicle, engine (4) is located inside the closed compartment (1) in which an opening is provided via tail door (2) to access the engine (4) during service. Tail door (2) is used to cover the engine (4) compartment and prevent thieving of parts inside engine (4) compartment.

In the present layout tail door (2) is hinged with compartment (1) by means of a hinge (3). Tail door (2) swings about vertical axis in specific value of angle from closed (Figure 1) to open (Figure 2) condition of the tail door (2). There is extra locking mechanism (2a) to arrest the degree of freedom of tail door in closed condition.

The salient features of the known door assembly is as follows

1. Compartment (1)
2. Tail door with locking provision (2)
3. Hinge (3)

Tail door (2) is hinged to the compartment (1) via two hinges (3) one at the top and another at the bottom. Tail door (2) opens out about the hinge axis (Z) to an allowed opening angle (Z1) (Figure 2). In closed condition of the tail door

(Figure 1) the tail door (2) butts against the compartment (1). A separate locking mechanism (2a) is provided to prevent the tail door (2) from opening out on its own. The major drawbacks with the known door assembly are as follows

• Manual opening of tail door (1)
• Extra locking is a must
• Tail door (2) swings about vertical axis, which occupies more service area.
• Since there is no stopper in open condition of tail door (2), there is a chance of inadvertent retraction of tail door and injuring the serviceman while servicing the engine.
• Poor aesthetics.

This invention will now be described with reference to Figs. 3 and 4 of the accompanying drawings which illustrate by way of example, and not by way of limitation, one of its possible embodiments:

In the embodiment illustrated, the hinge mechanism is made of four-bar parallel drag mechanism, which has one degree of freedom about horizontal axis. The rotation of tail door (2) is controlled by gas spring (5) (pneumatic). Gas spring (5) is used to open the tail door (2) about horizontal axis, which also provides damping while closing. Self-locking arrangement is made with the help of gas spring(5) when opened and closed. The major advantages of this invention are as follows

• Controlled opening of tail door (2)
• Automatic opening of tail door with the help of gas spring (5) (pneumatic)
• Self locking arrangement with the help of gas spring (5)
• More service area
• Better aesthetics.
• There is no retraction of tail door (2) while servicing the engine.
• Remote opening of the tail door (2)

Thus, engine (4) is enclosed inside the compartment (1) protected by the tail door (2). Four links (6 - 6a, 6b), two on either side, having top end (6j) of the link, hinged to the compartment via pin arrangement (6k). Bottom end of the link (6i) is hinged to the tail door via pin arrangement (6q). Both the top and bottom end of the link are free to rotate about the horizontal axis (Y). Two gas springs (5) are used for controlled opening (Figure 4) / closing (Figure 3) of the tail door (2). Each gas spring (5) is used on either side of the tail door (2). Bottom end (5a) of the gas spring is hinged on to the compartment (1) via pin mechanism (6m), having degree of rotation about its horizontal axis (Y) free. Top end (5b) of the gas spring is hinged on to the link (6n) via a pin mechanism (6p), having degree of rotation about its horizontal axis (Y) free.

To open the engine compartment (4) move the tail door (2) along the direction (D) to service the engine compartment (4) (Figure 4). During tail door (2) opening the link (6a, 6b) also rotates about its horizontal axis (Y) with the ssistance of the gas springs (5) opening. Similarly to close the engine compartment (4) move the tail door (2) along the direction (E).

During closing of the tail door (2), the links (6a, 6b) rotate about its horizontal axis (Y) with the assistance of the gas spring closing (5).

It will be appreciated that various other embodiments of this invention are possible without departing from its scope and ambit

We Claim:

1. A pneumatically controlled door assembly for closing and opening the door of a compartment, comprising links attached to the said door, the top and bottom ends of the links being free to rotate about the horizontal axis; at least one gas spring for controlled opening / closing of the door, the bottom end of the gas spring being hinged to the compartment and freely rotatable about its horizontal axis, while the top end of the gas spring is hinged to a link and freely rotatable about its horizontal axis.

2. A pneumatically controlled door assembly for closing and opening the door of a compartment substantially as herein described and illustrated.