AUTOMATIC CONTROL SYSTEM FOR GUIDING A TRAILER UNDERNEATH OR FROM UNDERNEATH A LOAD-SUPPORTING CASSETTE

Abstract: The invention relates to an automatic control system for guiding a trailer underneath or from underneath a loadsupporting cassette (2) as centrically as possible with regard to the cassette, in order to avoid bumping against the wall and the leg constructions of the cassette as well as an uneven loading of the trailer. The automatic control system comprises a glide (3) transverse to the longitudinal axis of the trailer, the length of which in the operating mode of the control system is nearly equal to the width of the front edge and in the non-operating mode maximally equal to the width of the front edge. When the trailer is being driven underneath the cassette, the guide rolls (4) at the ends of the glide are in contact with the inner walls of the cassette and the glide moves with regard to the front edge of the trailer depending on the angle at which the trailer is driven in. The identifying sensors disposed in connection with the glide report to the electric control system on which side of the central line of the cassette the front edge of the trailer is situated. On the basis of the received message the electric system emits a control order to the pivoting axis (10) of the wheels.

Description: Automatic control system for guiding a trailer underneath or from underneath a load-supporting cassette This invention relates to an automatic control system for guiding a trailer underneath a load-supporting cassette of for removing it from there as closely as possible to the centre of the tunnel formed by the cassette, in other words to the automatic control system according to the beginning of the enclosed claim 1. The trailer lifts the legged cassette on top of itself and transfers it from one place to another, often over fairly short distances. Driving the trailer underneath the cassette forms an important part of this transport operation. The problem with the driving consists in its being difficult for the driver to guide the trailer underneath the cassette centrically with regard to the cassette over the entire distance. The problem is caused by the lack of visibility over the portion of the trailer situated below the cassette and the guiding wheel axis and by the small driving play between the cassette and the trailer. If the trailer has been excentrically driven underneath the cassette, it causes an uneven loading on the various sections of the wheel axis of the trailer as well as an unstable motion of the trailer. In the worst case, the trailer may be driven so far to the side underneath the cassette, that the wheels hit the leg constructions of the cassette and the tyres get damaged. The precision required when driving the trailer underneath the cassette slows down the entire operation. The FI Patent application 841 504 discloses such a control system. It operates by means of sensors measuring the distance disposed on the front part and at the front edge of the trailer. The difference between the recorded distance values is transmitted to the wheel axis, which corrects the direction of the wheels. The sensor disposed at the front edge signals when the trailer has reached its end position underneath the tunnel. When reversing the trailer from underneath the cassette, the maneuvre is effected in the same manner. The known control system does not however function quite satisf ctorily, the trailer groping slowly for the centre of the cassette. The purpose of this invention is to provide a safe and reli¬ able control system, which on the basis of data provided by simple sensors directs the trailer step by step directly underneath the cassette so that the longitudinal centre lines of the trailer and the cassette coincide essentially. This has been achieved by giving the control system according to the beginning of claim 1 the characteristics presented in the characterizing part of the claim. Thus, according to the invention, the automatic control system comprises a glide transverse to the longitudinal direction of the trailer, which is disposed at the front end of the trailer. The trailer and the glide are movable with regard to each other. The length of the slide in the operating mode of the control system is, with the exception of a minor operating play, equal to the inner width of the cassette, and in the non-operating mode maximally equal to the width of the front egde, in order to protect it in the non-operating mode from contacts with obstacles in the environment. In addition, the control system comprises identifying sensors, which identify the glide and consequently the position of the trailer with regard to the central line. During the entire introduction step the glide extends across the cassette and its outmost ends slide in the proximity of the inner walls of the cassette as the trailer advances. When the trailer moves inwards in an oblique angle and hits the other inner wall of the cassette, the glide slides into a direction opposite to the trailer. The identifying sensors connected to the glide identify to which side of the central point of the trailer the glide has moved and transmit these data to the control system and further to the wheel axis, or more precisely to the pivoting device of the wheel axis, which receives an order to turn the wheels into the opposite direction. The glide preferably consists of two coaxial glide sections interconnected by a coupling member. Owing to the coupling member, the glides are either spaced in the operating mode or close to each other in the non-operating mode. The glides are preferably placed sideways into a tubular body, in which they move. The tubular body is disposed at the front end of the trailer, which is narrower than the rear end. The identifying sensors are disposed in connection with the tubular body and identify on which side of the central point the glide is situated and transmit a corresponding order to the pivoting device of the wheels . The control system preferably comprises two photocells, which are placed at the front end of the trailer, at the sides of the part having full width, behind the glides. When both the photocells give an order about an obstacle appearing in front of them, i.e. the side walls of the cassette, the electric control system is preferably switched on and the glides move apart into the operating position. In addition, the control system preferably comprises a weight identifier, which, the control system being switched on, identifies the weight of the cassette as it loads the trailer in the hoisting situation and, respectively, the weight loss in the depositing situation of the cassette, giving an order about switching off the control system and, respectively, switching it on. The control system is preferably disposed to function cyclically, alternating in the identifying mode and the resting mode according to the desired time control. In this situation, the wheel axis receives a control order in the identifying mode, in case a correction of the direction is required, and in the resting mode it returns into the direct mode. An automatic control system of this design is easy to set up and has a reliable function. Since the corrective controls are effected step by step within a short period of time, the movements are calm and do not stress the constructions super- fluosly . A preferred embodiment of the invention is described in detail below, referring to the enclosed figures, in which figure 1 presents a side perspective of the front end of a trailer equipped with the control system according to the invention, as driven underneath the cassette partly represented by dotted lines, figure 2 presents a top perspective of figure 1, the trailer being in the central position, figure 3 presents a section perspective of figure 2 along the line III-III, figure 4 presents the same as figure 2 (some details not presented) however with the trailer in front of the cassette before it is driven underneath the cassette and figure 5 presents the glides and the interconnecting coupling member as well as the tubular body of the glides, with all the elements detached. In the figure, the same parts are marked by the same reference numerals. The trailer is marked by number 1, the cassette by number 2, the glides by number 3, the guide rolls disposed at the outer ends of the glides by number 4, the tubular body of the glides by number 5, the identifying sensors disposed into the tubular body by number 6, the interconnecting coupling member of the glides by number 7, the photocells at the front edge of the trailer by number 8, the electric control system by number 9 and the pivoting axis of the trailer wheels by number 10. In figure 4, the trailer is shown just before it is driven underneath the cassette. The automatic control system has consequently not been switched on yet and the glides 3 with their guide rolls 4 are inside the tubular body 5. When the trailer is being directed towards the mouth opening of the cassette, the narrower front part of the trailer guides the movement. The narrower front part easily settles into the mouth opening. Not until both photocells 8 of the trailer have reached the lateral surfaces of the cassette does the photo¬ cell emit an order, causing the electric control system 9 to be switched on and the glides to be spaced up to the identi¬ fying width by means of their interconnecting hydraulic cylinder 7. When the trailer advances in the tunnel of the cassette in a direction that probably deviates from the one of the central line, the guide rolls 4 at the ends of the glides 3 move along the walls of the tunnel and the glides 3 slide in a direction opposite to the driving direction of the trailer in the tubular body fixed to the trailer. If the trailer drives obliquely to the left, the glide slides to the right in the tubular body 5 of the trailer. Thus the left-hand glide gets in front of the left-hand identifying sensor 6, whereby the electric control system receives a signal about the trailer being on the left side of the central line and a control order about turning the wheels to the right is emitted to the pivoting axis 10 of the wheels. The electric control system operates cyclically, being in the identifying mode and the resting mode in alternating cycles. The length of the cycles is adjustable. In this situation, the wheels of the trailer are turned into the corrective direction during an identifying cycle and turned straight during the following resting cycle. During the following identifying cycle the wheels are probably ordered to turn further to the right, however, the direction of the trailer and thus the corrective direction may vary while the trailer is being driven underneath the cassette. The identifying sensors are microβwitches and may function for instance inductively or mechanically. Their task is to report to the electric control system only on which side of the central line of the trailer and thus also of the cassette the glides 3 are situated at each particular moment, whereby a corresponding control order is emitted to the pivoting axis 10 of the wheels. The automatic control system is in operation, alternating in the identifying and the resting mode all the time while the trailer is being driven underneath the cassette. The driver can see when the trailer is entirely underneath the cassette and stops the trailer at that point. When the trailer plat¬ form is being hoisted under the driver's guidance and the - cassette is supported by the platform, the automatic control system is switched off. This occurs under the effect of the weight identifier, which identifies the weight of the cassette. Correspondingly, the cassette having been brought to its destination and being deposited on the ground, the weight identifier switches on the system when the platform is no longer loaded. Thus, the control system functions exactly in the same way when the trailer drives away from underneath the cassette as when it drives underneath the cassette. When there is no longer any wall or base part of the cassette in front of the photocells, the control system is switched off and simultaneously the glides retract into their inner position inside the tubular body. In this position they are prevented from sliding by means of the stoppers (not presented here) in the tubular body. Individual partial solutions may vary within the scope of the , inventional idea. It is for instance obvious that the hydraulic cylinder between the glides, which maintains the glides either in the inner or the outer position, can be replaced by some other coupling member. The whole glide system may vary in several ways. The essential is that the member extending above the cassette and the front device of the trailer move with regard to each other and that this movement effects a signal to the control system indicating into which direction the wheels should be turned in order to correct the direction.

Claims: C1aims 1. Automatic control system for guiding a trailer (1) under¬ neath or from underneath a load-supporting cassette (2) with legs as centrically as possible with regard to the cassette, comprising an identifying member disposed at the front end of the trailer which identifies the walls of the cassette as well as control systems, by means of which the impulses of the identifying members are transmitted eventually to the pivoting device (10) of the wheels of the trailer as guiding orders, characterized in that the identifying member consists of a glide (3) transverse to the longitudinal axis of the trailer (1), the length of which in the operating mode of the control system is essentialy equal to the inner width of the cassette and in the non-operating mode maximally equal to the width of the front edge of the trailer (1), and the position of the trailer with regard to the glide is identified by identifying sensors (6), which in a manner known per se transmit their data to the control system and further to the pivoting device (10) of the wheels. 2. A system according to claim 1, characterized in that the glide consists of two coaxial glide members (3), which by means of an interconnecting coupling member (7) are either spaced in the operating mode or close to each other in the non-operating mode. 3. A system according to claim 1 or 2, characterized in that a guiding roll (4) is provided at both the outer ends of the glide (3) . 4. A system according to any of the preceding claims, char¬ acterized in that the glides (3) are disposed to move in the tubular body (5), which is situated at the front edge of the trailer (1), at its narrowest point. 5. A system according to claim 4, characterized in that the identifying sensors (6) are disposed in the tubular body ( 5 ) . 6. A system according to any of the preceding claims, char¬ acterized in that preferably an electric control system (9) is disposed to be switched on and glides (3) are disposed to be brought into the operating position at the order of two photocells (8) which are situated at the front end of the trailer, at the sides of the section having full width, behind the glides. 7. A system according to any of the preceding claims, char¬ acterized in that the automatic control system is disposed to be switched off and respectively, to be switched on, when the trailer is driven underneath the cassette under the effect of the weight identifiers, in such a way that when the cassette loadε the trailer (1) in the hoisting position the control is switched off and correspondingly, when the load is removed in the depositing position of the cassette, the control is switched on. 8. A system according to any of the preceding claims, char¬ acterized in that it alternates in the identifying mode and the resting mode according to the desired time control, whereby the wheel axis, when needed, receives a control order in the identifying mode and returns automatically into the direct mode in the resting mode.

Inventors: MAEKINEN JORMA, MAEKINEN, JORMA
Applicants: ELECTROLUX AB, OY ELECTROLUX AB
Application year: 1988
Main classification: B60P1
IPC codes: B60P1, B62D1, B62D13