Patent Application
20190145143
The present invention relates to a door opening and closing system.
In many applications, a door is used to secure access to a confined storage space. Hence forth, any door, lid, or cover is hereafter referred to as a door. In certain applications, the door acts as a seal isolating the storage space from the environment. In these applications, a heavy door is used as a structural reinforcement and also as a natural barrier. It is also particularly beneficial where cleanliness is a concern. Some examples are shown in
In
Often it is required for the door to remain closed under its own weight if there are no external forces. Thus, the present invention applies when the door, when closed, is:
The present invention applies when the door, when closed, is:
In all subsequent figures, it is assumed that the door is shown as horizontal when closed and sitting on top of the panel as indicated in
The typical way to accomplish the objective is with one or two gas struts as shown in
To close the door, the operator pulls against the force of the gas strut; the weight of the door helps the user. As the door closes, the weight of the door overcomes the force of the gas strut and the door closes fully. This approach has worked well for years, but has several disadvantages:
Alternative methods can use a special hinge. There are two main types of special hinges: the torque hinge and the self-closing hinge.
For a torque hinge, this provides a constant torque in the opening direction and a constant torque in the closing direction. These two torque values may be the same or different (resulting in an asymmetric torque hinge). The asymmetric torque hinge may be preferred. It is shown in
The characteristics of the hinge are shown in
Where the line 0403 intersects line 0402 indicates the angle at which the door will be held by the hinge (to the right of the intersection) or where it will fall under its own weight (to the left of the intersection). This point is marked as 0404 on
This type of hinge allows the user to easily open the door. The low torque 0401 in
(i) The door, being heavy, is hard to open. The assistance of the gas strut that was used in
(ii) The torque hinge is resisting the closing of the door. [This is easily seen on the display of a laptop computer. When the display is open, if you move the end of the display just a few mm, it will return to its original position. Making the laptop display close completely is difficult and many earlier models would leave the display slightly open by a few mm.] With this type of hinge it is impossible to close the door completely and it will remain open a few mm. This can be overcome by the addition of a latch installed at the front of the door to hold the door closed. However, it is an objective of the present invention that a latch should not be present as this adds to the disadvantages of the current state of the art as described above.
(iii) As the door closes, the torque that the door presents on one side of the hinge results in a reactionary torque (equal and opposite) on the other side of the hinge. This results in a force pushing the hinge down and thereby rotating its mounting plate as the door is closed. This is shown in
(iii)(a) In
(iii)(b)
(111)(c)
For the self-closing hinge, it presents minimal toque to open or close the door. It has a damper mechanism on closing so it allows the door to close on its own slowly. This hinge is commonly used on toilet seats. This type of hinge is installed the same way as the torque hinge shown as 0302 in
There are two problems with this type of hinge:
(i) The hinge will not hold the door open at any angle. It must be opened nearly 90° or more to ensure it will not fall back to the closed position. This means that it requires a support to hold it just past the vertical point. The support structure is undesirable in most situations and it can be inconvenient to have to open the door so far.
(ii) Users may want to close the door themselves. They will try to overcome the damping force in the hinge. With current technology, the life of these hinges is about 10,000 cycles and forcing the door closed will reduce the life of the hinge.
It is apparent that the use of readily available technologies to solve the problem cannot be deployed.
The foregoing summary, as well as the following detailed description of the preferred embodiments of the invention, will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, there is shown in the drawings embodiments which are presently preferred. It should be understood, however, that the invention is not limited to the precise arrangement shown.
A door support includes a first shaft coupled to the door for rotating a door; a first armature on the first shaft; a link module on the armature to enable the door to be fully closed without resistance; a second shaft with a motion-resistant module thereon; a second armature on the second shaft coupled to the link module, wherein as the first shaft rotates the second shaft rotates; and a freewheel on the second shaft and coupled to the motion-resistant module, wherein the freewheel enables door opening without resistance and door closing engages the motion resisting motion on the second shaft.
The preferred embodiment enables a relatively heavy door that may be opened easily by a person. The door remains in place while open and may be closed completely with minimal effort by a person. The door is hinged and that once opened, nothing impedes the access to the opening. Once the door is opened beyond a certain angle it can stay open without any supplemental devices being required. The mechanism should last at least 30,000 openings before requiring replacement of any part.
Certain terminology is used in the following description for convenience only and is not limiting. The words “top,” “bottom,” “inner,” and “outer” designate directions in the drawings to which reference is made. The terminology includes the words specifically noted above, derivatives thereof, and words of similar import.
An easy to open door support includes:
The door hinge support mechanism is shown in more details in
As the door closes, the hinge mechanism should present increasingly less torque until point 0605 where it presents zero torque. This point 0605 is not at 0° but it at about 5° to ensure there is no resistance to the door fully closing.
The curved shape of line 0602 mimics somewhat that of 0603 so that the torque that the operator must apply to close the door (shown as 0606) is reasonably large until the door is closed at a certain point (perhaps 45°). This will help to prevent the operator from accidentally knocking the door and the door closing itself when that was not desired.
A. Operation Description
A.1. Basic principle
The basic principle is shown in
An armature 0803 also fixed to the shaft and rotates as the shaft rotates (and therefore as the door opens). The shaft 0802 does not need to rotate, but the armature 0803 must rotate in concert with the door 0801. The armature 0803 may be fixed directly to the door 0801 or to a hinge that itself is fixed to door 0801. However, fitting these items on a shaft that itself rotates is the easiest and simplest way of accomplishing the preferred embodiment.
A second shaft 0805 has the torque mechanism (not shown). This shaft has an armature 0806 which rotates about shaft 0805. The armature 0806 is connected to armature 0803 by link 0804. Link 0804 has holes 0807 and 0808 which have bolts or some other pivot points to fix it to the armatures 0803 and 0806.
As the door opens (in direction 0811) armature 0803 rotates in the same direction (as shown, anti-clockwise) and armature 0806 rotates in the opposite direction 0813 (as shown, clockwise). As the door closes (direction 0812) armature 0803 rotates clockwise and armature 0806 rotates anti-clockwise (direction 0814).
It is possible to arrange the preferred embodiment so that the shafts 0803 and 0806 always rotate in the same direction. However, as explained below, there are advantages to having the shafts rotate in opposite directions.
The torque mechanism (comprising shaft 0805 and armature 0806 and other parts as described below) provides no resistance when rotating clockwise (direction 0813) and provides resistance when rotating anti-clockwise (direction 0814).
Therefore there is no resistance to the door being opened but there is resistance to the door closing.
A.2 Achieving No Resistance Close to Zero Degrees
The objective as described above is that there should be no resistance presented to fully closing the door. The solution in the preferred embodiment is shown in
The door 0821 is shown in the closed position. The door 0821 is fixed to shaft 0822 as is the armature 0823.
The link 0824 is connected to armature 0823 at point 0827 and to armature 0826 at point 0828. Armature 0826 rotates about shaft 0825 which has the torque mechanism.
When the door 0821 is closed, the center points of shaft 0822, connector 0827, and connector 0828 are in line as shown by line 0830. A small movement of the door (opening 5°) causes little or no movement in link 0824. Therefore, there is little or no movement in armature 0826 and consequently, little or no movement in torque shaft 0825. Therefore, as the door closes, the resistance that was acting against the door being closed collapses to zero. This allows the door to close fully under its own weight without resistance or obstruction from the torque mechanism.
In practice, perfect alignment of 0822, 0827, and 0828 as indicated by line 0830 is not required, and there can be a misalignment of ±2° before the door may not close fully.
To further improve the closing, armature 0826 is positioned such that it is perpendicular to link 0824 when the door is closed. Thus the line 0831 which passes through the center of 0825 and 0828 is at 90° to line 0830. The effect of this condition is significantly smaller than the effect described above by aligning the armature 0823 and link 0824.
A.3 Explanation of Torque Mechanism
The major components are a freewheel mechanism and a friction or damping mechanism. There are many ways of using these to implement the preferred embodiment. These components can be implemented with products that are readily available or with custom made components. Damping mechanisms are readily available and can be easily fixed to the end of the shaft 0805 in
Friction mechanisms with sufficient torque capability are harder to locate as standard products and two examples are described below.
The freewheel mechanism is easily found as a standard part that can use a ratchet, balls, or sprags. Devices using sprags are often called sprag clutches, sprag bearings, or one way bearings. A one way bearing is shown in
In
A.3.i First Method: Using Friction Mechanism Created by Shaft Turning
The friction mechanism is implemented as shown in
The bolts 1004 connect to plate 1041 by passing through holes 1042. Nuts 1051 fit over bolts 1004. There may be washers and secondary nuts used as lock nuts but these are immaterial to the operation of the preferred embodiment.
Plate 1041 is therefore fixed to plate 1001 so that it cannot rotate. It is called a floating plate.
Between plates 1001 and 1041 are three washers 1011, 1021, and 1031. Washers 1011 and 1031 would usually be made of the same material and can rotate about shaft 1061. Washer 1021 would be made of a hard material such as steel. It has a notch 1022.
When the shaft 1061 is in position, the key 1063 fits into notch 1062 and matches the notch 1022 on washer 1021. When the shaft 1061 rotates, washer 1022 rotates, but plates 1001 and 1041 do not rotate.
The bolts 1004 are fastened tightly with nuts 1051 so that as washer 1022 rotates it creates friction against the surfaces of washers 1011 and 1031. These washers 1011 and 1031 will also try to rotate and create friction against plates 1001 and 1041 respectively. This friction is created regardless of the direction of rotation of shaft 1061. The amount of friction (and hence the torque this mechanism can provide) is proportional to the number and tightness (torque) of the bolts 1004.
If the plates 1001 and 1041 are made of the same metal and have the same finish as washer 1022, then the washers 1011 and 1031 are likely to rotate at about half the speed of shaft 1061 and washer 1021. The friction is twice that of using a single washer. Additional friction can be obtained by adding another pair of washers like 1021 and 1031 to the right of washer 1031. Similarly, it is possible to eliminate one or both of washers 1011 and 1031 so that washer 1021 presses directly against plates 1001 and 1041. The preferred embodiment applies to any number of fixed and free washers and any number of fixed and floating plates in a configuration as shown in
Further, it is possible to eliminate the key 1063. If the notch 1062 extends to the end of the shaft 1061, the rotating washer 1021 can have a protrusion that fits into notch 1062. This can make assembly easier, especially if there are multiple fixed and rotating sets of washers.
A suitable material for the plates 1001 and 1041 and for washer 1021 is steel. A suitable material for washers 1011 and 1031 is PTFE. However, the preferred embodiment is not limited to these materials or this combination of materials.
The friction mechanism described by
The bearings 1102 and 1103 are fixed to the same structure as the friction mechanism 1101. The bearings are shown in
Further, the method of mounting the bearing is not material to the preferred embodiment, whether the bearings be welded, bolted, clamped, or restrained in some other way. Also, the two bearings can be mounted at one end of the shaft to restrain the shaft with the other end of the shaft free and unsupported. It is important that the bearings and the friction mechanism be mounted on the same structure.
The shaft 1111 has notch 1112 and key 1113 which serve the purpose of 1062 and 1063 respectively in
The bearing 1105 also fits over shaft 1111. The relative position of bearing 1105 and friction mechanism 1101 is not material to the preferred embodiment and their position on the shaft could be interchanged.
The bearing 1105 is a one way bearing. The bearing is installed such that when the inner part of the bearing is restrained, the outer part can rotate freely in the direction 1121 and will engage in the direction 1122. The one way bearing can be replaced by any freewheel mechanism described above.
The bearing 1105 has notch 1106 and the shaft 1111 has notch 1114. The key 1115 fits into notches 1114 and 1106. When the outer part of the one way bearing 1105 is rotated in the direction 1121, the shaft will not turn. When the outer part of the one way bearing 1105 is rotated in the direction 1122, the bearing engages and the shaft will turn.
The armature 1108 is fitted over the bearing 1105. The protrusion 1109 fits into the notch 1107 so that as armature 1108 rotates so too does the outer part of bearing 1105. The method of fixing the armature 1108 to the bearing 1105 is not material to the preferred embodiment. It could be welded, pressed in place, bolted, clamped, or held in some other manner.
When this assembly is complete, the armature 1108 can rotate freely in the direction 1121. The shaft does not turn. When the armature 1108 is rotated in the direction 1122, the bearing 1105 is locked and the shaft must turn. When the shaft turns, friction mechanism 1101 restricts the movement and a torque must be applied to armature 1108.
The hole 1110 is used for the link mechanism. Thus the armature 1108, hole 1110, and shaft 1111 correspond to armature 0806, hole 0808, and shaft 0805 as described for
A.3.ii Second Method: Using Friction Mechanism Created by Armature Turning
The friction mechanism is implemented as shown in
The plates 1201 and 1241 may be identical. They have holes 1202 and 1242 through which pass bolts 1251. For clarity only one bolt is shown in
The bolts 1251 hold plates 1201 and 1241 together by being fixed by nuts 1252. There may be washers and secondary nuts used as lock nuts but these are immaterial to the operation of the preferred embodiment.
Plates 1201 and 1241 have larger holes 1203 and 1243 through which shaft 1261 will fit. The plates 1201 and 1241 also have notches 1204 and 1244.
Between plates 1201 and 1241 are two washers 1211 and 1231 and armature 1221. These three parts have a large hole 1212, 1222, and 1232 respectively that fit on the outside of the bolts 1251.
Washers 1211 and 1231 would usually be made of the same material and can rotate about shaft 1261. Armature 1221 would be made of a hard material such as steel and can also rotate about shaft 1261.
When the shaft 1261 is in position, the key 1263 fits into notch 1262 and matches the notch 1204 on plate 1201 and the notch 1244 on plate 1241. When the shaft 1261 rotates, plates 1201 and 1241 rotate.
The bolts 1251 are fastened tightly with nuts 1252 so that when the shaft 1261 is fixed (that is, when it does not rotate) the armature 1221 creates friction against the surfaces of washers 1211 and 1231. These washers 1211 and 1231 will also try to rotate and create friction against plates 1201 and 1241 respectively. This friction is created regardless of the direction of rotation of armature 1221. The amount of friction (and hence the torque on the armature) is proportional to the number and tightness (torque) of the bolts 1251.
If the plates 1201 and 0141 are made of the same metal and have the same finish as armature 1221, then the washers 1211 and 1231 are likely to rotate at about half the speed armature 1221. The friction is twice that of using a single washer. Additional friction can be obtained by adding another washer and plate like 1231 and 1241 to the right of plate 1241 or by adding another armature and washer, with the multiple armatures being connected through hole 1223. Similarly, it is possible to eliminate one or both of washers 1211 and 1231 so that armature 1221 presses directly against plates 1201 and 1241. The preferred embodiment applies to any number of plates, washers, and armatures in a configuration as shown in
A suitable material for the plates 1201 and 1241 and for armature 1221 is steel. A suitable material for washers 1211 and 1231 is PTFE. However, the preferred embodiment is not limited to these materials or this combination of materials.
The friction mechanism described by
One or both of the bearings 1311 and 1321 is a one way bearing. The bearing is (or the bearings are) installed so that they can rotate freely in the direction 1341 but are locked in the direction 1342.
The bearings 1311 and 1321 are fixed to the same structure as the top of the door cover. The bearings are shown in
One of the bearings could be a bushing, or for a very low cost solution, one bearing can be replaced with holes in metal so that the shaft 1331 rotates about this hole. The term bearing in this section will be used to describe a bearing, bushing, or hole.
Further, the method of mounting the bearing is not material to the preferred embodiment, whether the bearings be welded, bolted, clamped, or restrained in some other way. Also, the two bearings can be mounted at one end of the shaft to restrain the shaft with the other end of the shaft free and unsupported.
The shaft 1331 has notches 1332, 1334, and 1336 where the keys 1333, 1335, and 1337 fit. Any or all of the notches may be combined and any or all of the keys may be combined. The key 1333 fits into notch 1313 on bearing 1311; the key 1335 fits into the notches 1303 on friction mechanism 1301; and the key 1337 fits into notch 1323 on bearing 1321.
The relative position of bearings 1311 and 1321 and friction mechanism 1301 is not material to the preferred embodiment and their positions on the shaft could be interchanged.
When this assembly is complete, the armature on the friction mechanism 1301 can rotate freely in the direction 1341. The shaft 1331 does not turn in the direction 1342, so for the armature of friction mechanism 1301 to move in that direction it encounters friction as explained in the description of
The hole 1304 is used for the link mechanism. Thus the armature on friction mechanism 1301, hole 1304, and shaft 1331 correspond to armature 0806, hole 0808, and shaft 0805 as described for
B. Advantage of Counter Rotating Shafts
As explained above, the shaft for the torque mechanism (0805 in
The shaft 1402 provides no resistance when the door is opened or closed. Therefore the issue shown in
The shaft 1402 is coupled to the hinge mechanism which is on shaft 1403. The linkage mechanism is not shown but would be as previously shown in
In conclusion, the counter rotating shafts (of the pivot point of the door and that of the torque mechanism) aid in the ability to fully close the door. However, a single shaft (having the door and torque mechanism on the same pivot point) or two shafts (of the pivot point of the door and that of the torque mechanism) rotating in the same direction do not allow the door to fully close.
C. Addition of Springs to Lift Door
It is desired that the door be able to seal itself under its own weight. However, it should not be too heavy for a person to open. For example, if the weight door is 20 kg the force required to open the door (normal to the door) is about 100 N. This may be satisfactory if the door is at a person's waist height or lower, but is unsatisfactory if the door is at chest height or higher. In the latter case, a force of 30 N to 40 N is desired. This can be achieved by the addition of springs and three examples are shown in
In practice, it may be desirable to have one spring in the middle of shaft 1502 or multiple springs 1504 to ensure the force on the shaft (and hence on the opening of the door) is uniform. This may require multiple armatures 1503.
It would be possible to implement the preferred embodiment with a compression spring as shown in
D. Addition of Springs on the Torque Mechanism
With a heavy door, the amount of resistance required on the torque mechanism may generally necessitate the use of metal to metal for the washers of the torque mechanisms as PTFE may not provide the required friction. The friction created by the rubbing of metal against metal will cause wear on the mating faces. With the preferred embodiment, a typical amount of wear of 5 μm every 10,000 door openings is typical. This will reduce the pressure exerted by the bolts 1004 in
Conversely, if the door is opened often over a short period, the heat that is generated in the torque mechanism will raise the temperature of the elements between the plates (namely 1011, 1021, and 1031 in
Each of these outcomes is undesirable. By adding springs as shown in
In
In
E. Door Switch
It is often required to know when the door is closed or just open. This may be needed as a safety requirement if the door opens to reveal machinery that may be moving. Two examples of how this may be accomplished are shown in
In
In
With either of
F. Best Practices
It is advisable to make all components from stainless steel to prevent rusting and premature failure. Plain steel can be used in low cost applications or where it is known that the environment is dry.
The torque mechanism described in A.3.ii is preferred over that described in A.3.i when the door is light for the following reasons:
The washers 1211 and 1231 can be made of PTFE for doors that are light (under 3 kg). This provides a quiet torque mechanism. However, for heavier doors, the force required by the bolts 1251 exceeds the rated pressure on PTFE. Suitable materials for these washers for heavier doors include brass or steel. Because of the phenomenon called stick-slip, metal to metal used for the friction can be noisy. Brass to steel provides a lower coefficient of friction than steel to steel, but is quieter. Lead to steel is better because the static and kinetic coefficients of friction are nearly equal. Unfortunately, lead has environmental problems and is best avoided.
If the door is heavy, then the mechanism described in A.3.i is preferred over that described in A.3.ii for the following reasons:
If minor lubrication is used to reduce the noise created by stick-slip then brass to steel is preferred. The noise can also be reduced by polishing all components without significantly affecting the amount of torque. However, oils are easily squeezed out because of the very high pressures involved and are generally ineffective. If steel to steel is used, the washers 1211 and 1231 (in
The extension spring (shown in
While the above door closing and opening system can be used in many applications, one exemplary use is to add and secure the content of a waste food machine. For any type of such machine (wet, dry, or hybrid), the machine normally runs only when the door or doors are closed. For a wet type of machine, the door may be opened at any time so that additional waste food or additives can be added. For a dry type of machine, the methodology is a batch process, so once the process is started the door is kept closed and typically no further waste food can be added until the process is complete.
For a wet type of machine and referring to
For a dry type of machine, the structure is similar to the wet type. However, water and microorganisms are not typically added to the machine. Usually, the machine is loaded with waste food, the door is closed, and the machine heats the waste food. Typically, the temperature is raised to 90° C. for six to 10 hours and a cycle takes about 18 hours. The machine may churn the waste during this process with the objective of breaking it into small pieces. At the end of the cycle, the dehydrated waste is emptied through an output door 1813, which is typically not present on the wet type of machine. The dehydrated waste is typically 5% to 10% of the original volume of waste food.
A hybrid type machine may start with a decomposition process similar to a wet type of machine, and, after a certain time, for example, 12 hours, the machine may then dry the remainder of the waste food similar to a dry type of machine.
With the typical waste food machine, the door may be 10 to 25 kg and the height of the door, especially on machines that can process more than 100 kg of waste per day, is above the waist of an average person. It is desirable that the door is easy to open and it is essential that it should remain open so that the operator can put the waste food into the machine.
As a person adds waste food to the machine, invariably some of it will spill onto the top panel 1814 of the machine. That is, the waste food may spill either side of the door. The operator needs to clean this to avoid unhygienic conditions and having gas struts, catches, latches, and other such items in the way makes that job harder.
When the operator closes the door, it should close completely and remain in place under its own weight. In the case of a wet type of waste food machine, the door seals against the top panel to retain heat and moisture inside the drum. If the door remained open just a few mm the rate of digestion of the waste food will be affected.
It can therefore be seen that the present invention satisfies the requirements for a waste food machine very well. The door: is easy to open; stays open; is easy to close; shuts completely; remains shut to seal the drum.
While various methods, configurations, and features of the present invention have been described above and shown in the drawings, one of ordinary skill in the art will appreciate from this disclosure that any combination of the above features can be used without departing from the scope of the present invention. It is also recognized by those skilled in the art that changes may be made to the above described methods and embodiments without departing from the broad inventive concept thereof.
