Transmission system to transfer conveyor units from one floor chain system to another and method for hauling a conveyor unit from a main chain path to a side chain path

Abstract: The transmission system (5) contains two horizontal sprocket wheels (12 and 15) turning in the opposite sense over which run two floor chains (9 and 13) which carry protruding catch elements (10 and 14) for pins (17) of the conveyor units, and which are situated such that a pin (17) which is carried by a catch element (10) from the one floor chain system (2) is released from said catch element (10) at the height of the sprocket wheels (12 and 15) and is carried along by a catch element (14) from the other floor chain system (4), characterized in that the theoretical outline (25) which describes all the catch elements (10) of the one floor chain system (2) and the theoretical outline (26) which describes all the catch elements (14) of the other floor chain system (4), at the height of the theoretical joining line (20) between the shafts (18 and 19) of the two sprocket wheels (12 and 15), are situated at a distance from one another between zero and the thickness of the pins (17) in the direction of the above-mentioned joining line (20), whereas the transmission system (5) contains a kinematic connection (21-22) with a constant ratio between the two sprocket wheels (12 and 15).

Description: The invention concerns a transmission system to transfer conveyor units from one floor chain system to another, which transmission system contains two horizontal sprocket wheels turning in the opposite sense over which run two floor chains which carry protruding catch elements for pins of the conveyor units, and which are situated such that a pin which is carried by a catch element from the one floor chain system is released from said catch element at the height of the sprocket wheels and is carried along by a catch element from the other floor chain system, see for example the document FR-A-2659946 In known transmission systems of this type the paths of the catch elements of the two floor chain systems overlap at the height of the above-mentioned sprocket wheels, there where the actual transmission takes place, over a certain distance. This means that a theoretical line which describes all the catch elements of the one floor chain system and the theoretical line which describes all the catch elements of the other floor chain system intersect or cross one another at the height of the overlap. This has for a result that the ratio between the speed of the catch elements of the one floor chain system and the speed of the catch elements of the other floor chain system must be equal to 1 or can at the most be equal to 1/2 or 2/1. With other ratios the risk of a pin getting stuck sooner or later between a catch element of the one floor chain system and a catch element of the other floor chain system at the height of the overlap, whereby the transmission system is jammed, is very great. At different speeds the floor chain systems are driven separately, which makes the entire system expensive, whereas the drive devices require much space, especially as far as the built-in depth is concerned. The invention aims to remedy this disadvantage and to provide a transmission system to transfer conveyor units from one floor chain system to another one which is relatively inexpensive, requires relatively little space and allows for almost any transmission ratio whatsoever between both floor chain systems without any jam risks. This aim is reached according to the invention because the theoretical outline which describes all the catch elements of the one floor chain system and the theoretical outline which describes all the catch elements of the other floor chain system, at the height of the theoretical joining line between the shafts of the two sprocket wheels, are situated at a distance from one another between zero and the thickness of the pins in the direction of the above-mentioned joining line, whereas the transmission system contains a kinematic connection with a constant ratio between the two sprocket wheels. The above-mentioned outlines do not intersect or cross but touch one another just or almost. This avoids jamming, also at different speeds of the two floor chain systems and/or when the pitch between the catch elements of the one system differs from the pitch between the catch elements of the other floor chain system. Thanks to the gear wheels, it is sufficient to drive only one of the floor chain systems. Practically, the kinematic connection contains two clutching gear wheels which are connected coaxially to the two sprocket wheels respectively. If the pins are round, the above-mentioned distance between the outlines is practically smaller than 3/4 of the diameter of the pins and preferably smaller than 1/2 of this diameter. According to the most preferred embodiment, said distance is zero and the above-mentioned outlines touch one another. The two gear wheels may have a transmission ratio of 1/1 as well as another such as for example 2/1, 3/1, 3/2, 4/1, 4/3, 5/2, 5/3, 5/4, M/N, whereby M and N are whole, positive numbers of which M and N are the smallest common divisors. For different transmission ratios one only has to provide other gear wheels in one and the same transmission system. This allows for standardisation. For a good operation, one has to make sure that at least one catch element of the one floor chain system corresponds to at least one catch element of the other floor chain system, and such that if the one catch element stands on the joining line between the two shafts of the sprocket wheels or on the point of contact of the two described outlines of the catch elements, the other catch element lags at a distance or follows somewhat later. This distance may not exceed a value Q which is preferably smaller than twice the diameter of a pin and preferably smaller than 3/4 of the diameter of the pin. With a transmission ratio between the gear wheels of M/N = VN/VM , whereby VM is the rotational speed of the fastest sprocket wheel and VN is the rotational speed of the slowest sprocket wheel, and with a pitch P between the catch elements on both floor chain systems, the diameter of the pin must be, increased with Q and with a small clearance, preferably smaller than P/M (whereby M and N are the smallest common divisors). According to a peculiar embodiment of the invention, P1/P2 = VN/VM = N/M is possible, whereby P1 is the pitch of the one, faster, floor chain system with a speed VM, and P2 is the pitch of the other, slower, floor chain system with a speed VN. In a following peculiar embodiment of the invention this constant ratio may be altered with (M.Y)/(X.N), whereby Y and X are the smallest common divisors and whereby a multiple of M.Y is the rotational speed of the fastest sprocket wheel and a same multiple of X.N is the rotational speed of the slowest sprocket wheel. Hereby, the diameter of a pin must be, increased with Q and increased with a small clearance, preferably smaller than P2/Y. According to a peculiar embodiment of the invention the transmission system contains a spring pawl which, as seen in the direction of movement of the pins, is mainly situated before the point where the outlines are situated closest together and which is brought in the path of the pins by means of a springy element, so that a pin which moves towards said point must push away this pawl in a springy manner and cannot go back due to the pawl. The pawl slows the pins somewhat down and makes sure that the pins are connected to the catch element, but most of all it prevents the conveyor unit from being moved in a direction opposite its normal direction of movement at a moment during the transmission at which the catch element of the one floor chain system has already released the pin, but no catch element of the other floor chain system is situated behind the pin yet. The invention also concerns a method for hauling a conveyor unit from a main chain path to a side chain path whereby a transmission system according to any of the preceding embodiments is practically used. Thus, the invention concerns a method for hauling a conveyor unit from a main chain path which forms a floor chain system to a side chain path which forms another floor chain system, whereby a branch is present which forms yet another floor chain system which is connected onto the main chain path via a switch on the one hand and onto the side chain path via a transmission system on the other hand and whereby the branch as well as the main chain path and the side chain path consist of endless floor chains which can be driven separately and which carry catch elements which work in conjunction with pins of the conveyor units in order to carry along the latter and whereby during the haulage the floor chain of the branch is driven at a higher average speed than the floor chain of the side chain path. The side chain path is mostly used for shunting conveyor units which are disconnected later from the side chain path and possibly connected again to the main chain path. The side chain path is usually driven discontinuously. Each time a new conveyor unit is hauled via the branch, the shunted conveyor units move up one place. The aim of the different speeds between the floor chains is to let the haulage take place as fast as possible and, in case conveyor units are shunted on the side chain path, to make it possible to shunt these conveyor units as close as possible to one another without colliding. However, the speed of the floor chain of the branch may not be much higher than the speed of the floor chain of the main chain path, since the acceleration at the time of the transfer of the conveyor unit from the branch to the floor chain would be too great. The invention aims to remedy this disadvantage and to provide a method with which the haulage can be done relatively fast but yet smoothly. This aim is reached according to the invention because, at the beginning of the haulage of a conveyor unit, the floor chain of the branch is driven at a speed which is more or less equal to that of the floor chain of the main chain path, and only afterwards is the floor chain of the branch speeded up to a maximum speed which is higher and which is maintained almost until the conveyor unit is at the height of the transmission system, after which the floor chain of the branch is slowed down again. According to a peculiar embodiment, the floor chain of the branch is driven discontinuously and this floor chain is speeded up already from standstill to a speed which is practically equal to the speed of the floor chain of the main chain path before the conveyor unit is hauled to the floor chain of the branch. Practically, a transmission system according to any of the preceding embodiments is used as a transmission system. In this embodiment, also the floor chain of the side chain path is driven discontinuously. Preferably, the average speed of the floor chain of the side chain path when being driven is hereby slower than the speed of the floor chain of the main chain path. When the side chain path is a shunting track with stops for the conveyor units, the average speed of the floor chain of the branch and the average speed of the floor chain of the side chain path are selected such that a conveyor unit covers the distance between the switch and the transmission system in almost the same time as a conveyor unit is being moved from one stop to the next. In order to better explain the characteristics of the invention, the following preferred embodiment of a transmission system to transfer conveyor units from one floor chain to another one and of a method for hauling a conveyor unit from a main chain path to a side chain path, is described without being limitative in any way and with reference to the accompanying drawings, in which: figure 1 is a schematic representation of two floor chain systems with a transmission system according to the invention; figure 2 is a schematic representation to a larger scale of the transmission system from the floor chain system in figure 1; figure 3 represents the detail indicated by F3 in figure 2, to yet a larger scale; figure 4 represents a section according to line IV-IV in figure 2; figure 5 represents a section according to line V-V in figure 4; figure 6 represents a diagram with the speed of a part of the floor chain system as a function of time. The transport system represented in figure 1 contains a main chain path 1 which forms a first floor chain system, a branch 2 running away from it in a slanting manner which forms a second floor chain system and which is connected to the main chain path 1 at the height of a switch 3 and a side chain path 4 which forms a third floor chain system and is connected to the branch 2 by means of a transmission system 5 on the one hand, and which is connected to a drive 6 on the other hand. The main chain path 1 contains an endless floor chain 7 which carries a number of catch elements 8 and which is continuously driven by a drive which is not represented. The branch 2 also consists of an endless floor chain 9 which carries catch elements 10 and which runs over two sprocket wheels 11 and 12 of which one is situated close to the switch 3 and the other is part of the transmission system 5. The side chain path 4 in fact forms a shunting track and also consists of an endless floor chain 13 which carries catch elements 14 and which runs over two sprocket wheels 15 and 16. The sprocket wheel 15 is part of the transmission system 5, whereas the sprocket wheel 16 is discontinuously driven by the drive 6. The floor chains 7, 9 and 13 are worked into the floor and the catch elements 10 and 14 protrude horizontally sideways. The catch elements 8 of the floor chain 7 can be placed on top of the floor chain 8 (block chain) or laterally on the floor chain 8 (drag chain). These catch elements work in conjunction with the vertical, usually round pins 17 of conveyor units which, for clarity's sake, are not represented in figure 1. These conveyor units may be trolleys, pallet carriers, etc. which are equipped with wheels with which they roll over the floor when their pin 17 is carried along by a catch element 8, 10 or 14. The construction of the switch 3 is known as such and is not described in detail. In one position it lets the pins 17 through, whereas in another position it diverts the pins to the branch so that they can be carried along by a catch element 10. As is represented in particular in the figures 2 to 5, the two sprocket wheels 12 and 15 are mounted in a rotating manner around vertical shafts 18 and 19 in a housing 30. The theoretical joining line 20 between these shafts 18 and 19 forms an angle with the longitudinal direction of the active parts of the floor chains 9 and 13 at the height of the transmission system 5. These active chain parts are moved in the same direction since the sprocket wheels 12 and 15 rotate in the opposite sense as clutching gear wheels 21 and 22 are mounted on their shafts 18 and 19. The sense of rotation of the chain wheels 12 and 15 is indicated in figures 2 and 3 by arrows 23 whereas the direction of movement of the used parts of the floor chains 9 and 13 are indicated by arrows 24. Characteristic of the invention is the fact that the theoretical outline 25 which describes the catch elements 10 of the branch 2 and the theoretical outline 26 which describes the catch elements 14 of the side chain path 4 do not intersect or cross but touch one another right on said joining line 20. Instead of touching one another, these lines could be situated at a small distance from one another, which distance should be definitely smaller, however, than the diameter of the pins 17 and in practice even smaller than 3/4 and preferably even 1/2 of this diameter. The transmission system 5 works as follows: The floor chain 13 is driven by the drive 6. Via the gear wheels 22 and 21 the sprocket wheel 12 is driven at a greater speed in the ratio m/n, whereby m is the rotational speed of the gear wheel 21, and in the rotational speed of the driving gear wheel 22. The speed of the floor chains 9 and 13 has the same ratio. When a pin 17 and thus a conveyor unit is carried along by a catch element 10 of the branch 2, this pin 17 is released entirely from the catch element 10 right past said joining line 20, after which it is taken further along in the same direction by one catch element 14 of the side chain path 4. For clarity's sake, only one pin 17 is represented in figures 2 and 3, whereby said pin 17 is represented as a dashed line when it is practically released from the catch element 10. In order to make it possible for this pin 17 to be carried along by a catch element 14, the diameter of the pin 17 must be increased with a value Q and it must be smaller, with a small safety margin, than P/M, whereby P is the pitch, i.e. the distance between the catch elements 10 or 14 which is constant in the example represented and whereby Q is the lagging of the catch element 14 in relation to the catch element 10 at the moment when the catch element 14 is situated on the joining line 20. For a good operation, one must make sure that at least one catch element 10 of the one floor chain system 2 corresponds to at least one catch element 14 of the other floor chain system 4, and such that if this one catch element 10 stands on the joining line 20 between the two shafts 18 and 19 of the sprocket wheels 12 and 15 or on the point of contact of the two described outlines 25 and 26 of the catch elements 10 and 14, the other catch element 14 lags at a distance or follows somewhat later. This distance may not exceed a value Q which is preferably smaller than twice the diameter of a pin 17 and preferably smaller than 3/4 of the diameter of the pin 17. The transmission ratio M/N may have different values such as 1/1, 2/1, 3/2, 4/1, 4/3, 5/2, 5/3, 5/4, etc. without any risk of the pin 17 jamming the transmission system 5. The pitch P of the branch 2 may possibly differ from the pitch P of the side chain path 4. Since, at the moment when a pin 17 is released by a catch element 10, a catch element 14 is not necessarily situated behind said pin 17 yet, the conveyor unit could be pushed backward with said pin 17. In order to avoid this, the transmission system contains a pawl 27 which is hinge-mounted around a shaft 28 and is mainly situated in front of the joining line 20. Said pawl 27 is pulled in the position which is represented in figure 2 by a dashed line by a spring 29 and whereby the end of said pawl 27 is situated on the path of the pins 17. This pawl 27 is pushed away in a springy manner by a pin 17 which is carried along in the direction of the arrow 24. This pin is hereby slowed down somewhat. A movement of the pin in the opposite direction is prevented by the pawl 27. The above-described transmission system 5 makes it possible to make the speed of the branch 2 differ from the speed of the side chain path 4 when both are in motion. By replacing the gear wheels 21 and 22, this difference can be easily altered with one and the same transmission system. Moreover, one can vary the speed of the branch 2 in time, which offers particular advantages, whereby the speed of the side chain path 4 varies proportionally. Figure 6 represents a diagram with the speed of the branch 2 as a function of time. As can be derived from this diagram, the speed of the floor chain 9 of the branch 2 is varied according to the invention. One first speeds up from zero to an intermediate value A which is practically equal to the speed of the main chain path 1, and such before the pin 17 of a conveyor unit reaches the switch 3. At the time of the transfer t1 of this pin to the floor chain 9, the latter moves already at practically the same speed as the floor chain 7, as a result of which the transfer can take place very softly and smoothly. This speed is maintained for a while and at the time t2, at which the pin has reached the position X represented in figure 1, the floor chain 9 is speeded up to a speed B which is significantly higher. This speed, reached at t3, is maintained for a while until t4, at which time the pin 17 reaches the transmission system 5 or reaches it almost or has already reached it. Afterwards, the floor chain 9 is slowed down to a standstill. The maximum speed B is selected such that the pin 17 has covered the distance L before a new pin 17 has arrived at the switch 11. This implies that the pin 17 must be able to cover the distance between two stops in the chain system at the same time. The transfer can take place at maximum speed, during a speed reduction or during an acceleration. The average speed of the endless chain 13 of the side chain path can be selected freely in this manner. Preferably, this speed is selected slower than the speed of the main chain path 1. It is clear that the speed of the floor chain 13 of the side chain path 4, due to the fixed transmission ratio of the gear wheels 21 and 22 of the transmission system 5, will vary together with the speed of the floor chain 9. The haulage can in this way take place very fast but smoothly and without sudden shocks.

Claims: Transmission system to transfer conveyor units from one floor chain system (2) to another (4), which transmission system (5) contains two horizontal sprocket wheels (12 and 15) turning in the opposite sense over which run two floor chains (9 and 13) which carry protruding catch elements (10 and 14) for pins (17) of the conveyor units, and which are situated such that a pin (17) which is carried by a catch element (10) from the one floor chain system (2) is released from said catch element (10) at the height of the sprocket wheels (12 and 15) and is carried along by a catch element (14) from the other floor chain system (4), characterized in that the theoretical outline (25) which describes all the catch elements (10) of the one floor chain system (2) and the theoretical outline (26) which describes all the catch elements (14) of the other floor chain system (4), at the height of the theoretical joining line (20) between the shafts (18 and 19) of the two sprocket wheels (12 and 15), are situated at a distance from one another between zero and the thickness of the pins (17) in the direction of the above-mentioned joining line (20), whereas the transmission system (5) contains a kinematic connection (21-22) with a constant ratio between the two sprocket wheels (12 and 15). Transmission system according to the above claim, characterized in that the kinematic connection (21-22) contains two clutching gear wheels (21 and 22) which are connected coaxially to the two sprocket wheels (12 and 15) respectively. Transmission system according to any of the above claims, characterized in that the pins (17) are round and in that said distance between the outlines (25 and 26) is smaller than 3/4 of the diameter of the pins (17). Transmission system according to the above claim, characterized in that said distance between the outlines (25 and 26) is smaller than 1/2 of the diameter of the pins (17). Transmission system according to the above claim, characterized in that said distance between the outlines (25 and 26) is zero and in that these outlines touch. Transmission system according to any of the above claims, characterized in that at least one catch element (10) of the one floor chain system (2) corresponds to at least one catch element (14) of the other floor chain system (4), and such that if this one catch element (10) stands on the joining line (20) between the two shafts (18 and 19) of the sprocket wheels (12 and 15) or on the point of contact of the two described outlines (25 and 26) of the catch elements (10 and 14), the other catch element (14) lags at a distance or follows somewhat later, whereby this distance does not exceed a value Q which is preferably smaller than twice the diameter of a pin (17) and further preferably smaller than 3/4 of the diameter of the pin (17). Transmission system according to any of the above claims, characterized in that the kinematic transmission between the sprocket wheels (12 and 15) has a ratio which differs from 1. Transmission system according to any of the above claims, characterized in that the transmission ratio of the kinematic transmission between the sprocket wheels (12 and 15) M/N = VM/VN , whereby VM is the rotational speed of the fastest sprocket wheel (12) and VN is the rotational speed of the slowest sprocket wheel (15), and with a pitch P between the catch elements (10 or 14) on both floor chain systems (2 and 4), the diameter of the pin (17), increased with the value Q and with a small clearance, is smaller than P/M. Transmission system according to any of the above claims, characterized in that P1/P2 = VN/VM = N/M , whereby P1 is the pitch of the one, faster, floor chain system (2) with a speed VM, and P2 is the pitch of the other, slower, floor chain system (4) with a speed VN. Transmission system according to the above claim, characterized in that this constant ratio P1/P2 may be altered with (M.Y)/(X.N), whereby Y and X are the smallest common divisors and whereby a multiple of M.Y is the rotational speed of the fastest sprocket wheel (12) and a same multiple of X.N is the rotational speed of the slowest sprocket wheel (15), whereby the diameter of a pin (17), increased with Q and increased with a small clearance, must be preferably smaller than P2/Y. Transmission system according to any of the above claims, characterized in that it contains a spring pawl (27) which, as seen in the direction of movement of the pins (17), is mainly situated before the point where the outlines (25 and 26) are situated closest together and which is brought in the path of the pins (17) by means of a springy element (29), so that a pin (17) which moves towards said point must push away this pawl (27) in a springy manner and cannot go back due to the pawl. Method for hauling a conveyor unit from a main chain path (1) which forms a floor chain system to a side chain path (4) which forms another floor chain system, whereby a branch (2) is present which forms yet another floor chain system which is connected onto the main chain path (1) via a switch on the one hand (3) and onto the side chain path (4) via a transmission system (5) according to claim 1 on the other hand and whereby the branch (2) as well as the main chain path (1) and the side chain path (4) consist of endless floor chains (9-7-13) which can be driven separately and which carry catch elements (10-8-14) which work in conjunction with pins (17) of the conveyor units in order to carry along the latter and whereby during the haulage the floor chain (9) of the branch (2) is driven at a higher average speed than the floor chain (13) of the side chain path (4), characterized in that at the beginning of the haulage of a conveyor unit, the floor chain (9) of the branch (2) is driven at a speed (A) which is more or less equal to that of the floor chain (7) of the main chain path (1), and only afterwards is the floor chain (9) of the branch (2) speeded up to a maximum speed (B) which is higher and which is maintained almost until the conveyor unit is at the height of the transmission system (5), after which the floor chain (9) of the branch (2) is slowed down again. Method according to the above claim, characterized in that the floor chain (9) of the branch (2) is driven discontinuously, and in that this floor chain (9) is speeded up already from standstill to a speed (A) which is practically equal to the speed of the floor chain (7) of the main chain path (1) before the conveyor unit is hauled to the floor chain (9) of the branch (2). Method according to any of claims 12 and 13, characterized in that as a transmission system (5) is used a transmission system according to any of claims 1 to 11. Method according to the above claim, characterized in that the floor chain (9) of the side chain path (4) is driven at a slower average speed than the speed of the floor chain (7) of the main chain path (1). Method according to any of claims 12 to 15, characterized in that with a side chain path (4) being a shunting track with stops for the conveyor units, the highest speed (B) of the floor chain (9) of the branch (2) and the average speed of the floor chain (13) of the side chain path (4) are selected such that a conveyor unit covers the distance between the switch (3) and the transmission system (5) in almost the same time as a conveyor unit is being moved from one stop to the next.

Inventors: VAN LIERDE CARLOS, VAN LIERDE, CARLOS
Applicants: EGEMIN ELEKT GOEDER MARINE IND, ELEKTRICITEIT VOOR GOEDERENBEHANDELING MARINE EN INDUSTRIE, IN HET VERKORT EGEMIN, NAAMLOZE VENNOOTSCHAP
Application year: 1995
Main classification: B61B10
IPC codes: B65G17, B65G47, B61B10