In the beginning barriers used at crossings of roads and railways were moved on a purely mechanical way using chains, chain wheels, steel wires, springs, etc. As it was required by the increasing traffic, local driving mechanisms with electric motors have become usual. An electric motor with reductor chainwheel and a guiding camshaft is a quite widespread solution (see e. g. description No. US 3 964 707).

In case of failure of the power supply of the electric motor as a consequence of a possible operating trouble or intentional impairment, or if the battery is stolen, these old fashioned barriers can not be operated.

Further, solutions where some other kind of energy is used besides electricity (primarily hydraulic energy) are also known. Patent No. DE 3743347 describes such an electric driven barrier that is supplied with a hydraulic breaker drum. In case of these solutions the accidental failure of power supply leads to trouble of operation, uncertain position of the barrier and as a result, it causes danger of accident. A common shortage of all the known barrier-operating devices is that the duration of the opening and closing periods can not be varied, or can be varied only within a small range.

My intention was to eliminate the shortages of the known barrier operating devices, that is, to construct a device that operates on a much more reliable way than the solutions described above, which is able to operate on safely for a certain time in case of failure of the power supply required for the operation the device, able to complete the opening or closing cycle that has been started in case of fault of operation. Further, the device is able to close the barrier automatically if necessary in case if the fault takes place in the open position, or to keep the closed position of the barrier in case if the fault takes place in the closed position.

The basic idea of the invention is that if we construct an electrohydraulic barrier operating device comprising an electrohydraulic control unit connected to an hydraulic power package that is provided with an hydraulic accumulator, the operation of the device becomes safe.

In the course of normal operation this hydraulic accumulator can be charged continuously by the hydraulic power package preferably through a baroswitch (primarily in the resting- open or closed-position of the railing bar), so that the energy stored in the accumulator can be driven to the hydraulic appliance even in case of current failure, this hydraulic appliance is in torque transmission connection with the railing bar, so the railing bar can be brought into the required position by the operation of this hydraulic appliance initiated this way. In order that the energy stored in the hydraulic accumulator can be utilised in case of current failure, an electromagnetic valve that opens in case of current failure is to be inserted in the tube connecting the hydraulic accumulator with the hydraulic appliance operating the railing bar. In order to manage the required control functions and to perform the necessary operations, e. g. to operate displays, the device being the object of the present invention also comprises a code-sender imaging the actual position of the railing bar.

Therefore the invention relates to an electrohydraulic barrier operating device comprising an electrohydraulic control unit coupled to a hydraulic power package connected to the drive unit housing moving the closing bar connected to the railing bar having a counterbalance mounted on it. The essence of the invention is that it comprises a code-sender imaging the actual position of the railing bar, the code-sender is connected directly and/or indirectly to the electrohydraulic control unit. A hydraulic transmission unit that is in torque transmission connection with the railing bar is situated in the drive unit housing, the first operating input of the hydraulic transmission unit is connected to the first control output of the electrohydraulic control unit, the second operating input of the hydraulic transmission unit is connected to the second control output of the electrohydraulic control unit. The device comprises a hydraulic accumulator that is connected directly or indirectly to the feed pump of the hydraulic power package through a baroswitch and also connected directly or indirectly to the third operating input of the hydraulic transmission unit through a router valve operated by an electromagnet opening in case of current failure.

In an advantageous embodiment of the electrohydraulic barrier operating device according to the invention the hydraulic transmission unit being in torque transmission connection with the railing bar is constructed as a double-operated twin-piston hydraulic rotatory cylinder.

In a further advantageous embodiment of the electrohydraulic barrier operating device according to the invention the hydraulic accumulator is a steel vessel divided into two parts by an elastic membrane with compressed nitrogen gas in one part of it, the other part is formed so as to act as an oil space.

In an preferable solution of the electrohydraulic barrier operating device a first back-pressure valve is inserted between the router valve operated by an electromagnet opening in case of current failure and the third operating input of the hydraulic transmission unit, and a third back-pressure valve is inserted between the other part of the hydraulic accumulator and the router valve operated by an electromagnet opening in case of current failure.

In a further preferable solution of the electrohydraulic barrier operating device a fourth back-pressure valve is inserted between the hydraulic power package and the electrohydraulic control unit.

The electrohydraulic control unit preferably comprises a second router valve controlled by electromagnets, one connection of the second router valve is connected to the fourth back- pressure valve, the other connection of the second router valve is connected to one connection of a third router valve. The third and fourth connections of the second router valve serve as the first and second control outputs of the electrohydraulic control unit. The third router valve is operated by an electromagnet. Through a reduction valve, the third connection of the third router valve is connected to the second connection of the router valve operated by an electromagnet opening in case of current failure, and it is also connected to the oil filter of the hydraulic power package. Through the reduction valve the third connection of the third router valve is also connected to the fourth connection of the third router valve through a further reduction valve. The second connection of the third router valve is fed back before the further reduction valve and, on the other hand, through the pressure limiting unit, it is connected directly or indirectly to the feed pump of the hydraulic power package and to the other part of the hydraulic accumulator.

A possible implementation of the invention is described in detail as an example with reference to the attached drawings where Fig. 1 is a block diagram of the electrohydraulic barrier operating device, and Fig. 2 shows the schematic structure of the hydraulic control system.

The electrohydraulic barrier operating device of Figure 1. comprises an electrohydraulic control unit 5 coupled to a hydraulic power package 4 connected to the drive unit housing 1 moving the closing bar 3 connected to the railing bar 2 having a counterbalance E mounted on it. The device comprises a code- sender 9 imaging the actual position of the railing bar 2, the code-sender 9 is connected directly and/or indirectly to the electrohydraulic control unit 5. A hydraulic transmission unit 8 that is in torque transmission connection with the railing bar 2 is situated in the drive unit housing 1, the first operating input A of the hydraulic transmission unit 8 is connected to the first control output VA of the electrohydraulic control unit 5, the second operating input B of the hydraulic transmission unit 8 is connected to the second control output VB of the electrohydraulic control unit 5. The invention comprises a hydraulic accumulator 6 that is connected directly or indirectly to the hydraulic power package 4 through a baroswitch 5.6 and also connected directly or indirectly to the third operating input B'of the hydraulic transmission unit 8 directly or indirectly through a router valve 7 operated by an electromagnet opening in case of current failure.

On figure 1. the electric control and sent-back system R and the power supply T supplying the device with electricity is also indicated. The electric power supply T can be a separate unit as well, but it can also be connected to the known mains of the station AH. The electric control and sent-back system R receives the usual input commands BU used at railways, and produces and forwards the required output check-back signals KV.

Figure 2. shows the schematic structure of the hydraulic control system. In an advantageous embodiment of the electrohydraulic barrier operating device the hydraulic transmission unit 8 is constructed as a double-operated twin- piston hydraulic rotatory cylinder.

In the embodiment of the electrohydraulic barrier operating device shown on Figure 2 as an example the hydraulic accumulator 6 is a steel vessel divided into two parts 6.2 and 6.3 by an elastic membrane 6.1. Compressed nitrogen gas can be found in one part 6.2 of it, the other part 6.3 is formed so as to act as an oil space.

In an preferable solution of the electrohydraulic barrier operating device a first back-pressure valve V1 is inserted between the fourth connection of the router valve 7 operated by an electromagnet opening in case of current failure and the third operating input B'of the hydraulic transmission unit 8, a second back-pressure valve V2 is inserted between the third connection of the router valve 7 and the first operating input A of the hydraulic transmission unit 8, and a third back- pressure valve V3 is inserted between the other part 6.3 of the hydraulic accumulator 6 and the first connection of the router valve 7 operated by an electromagnet opening in case of current failure. A fourth back-pressure valve V4 is inserted between the hydraulic power package 4 and the electrohydraulic control unit 5.

The electrohydraulic control unit 5 shown on Figure 2 comprises a second router valve 5.2 controlled by electromagnets M1 and M2, one connection of the second router valve 5.2 is connected to the fourth back-pressure valve V4, the other connection of the second router valve 5.2 is connected to one connection of a third router valve 5.3. The third and fourth connections of the second router valve 5.2 serve as the first and second control outputs VA and VB of the electrohydraulic control unit 5.

The third router valve 5.3 is operated by the electromagnet M3.

Through a reduction valve 5.5 the third connection of the third router valve 5.3 is connected to the second connection of the router valve 7 operated by an electromagnet opening in case of current failure, and it is also connected to the oil filter 4.4 of the hydraulic power package 4. Through the reduction valve 5.5 the third connection of the third router valve 5.3 is also connected to the fourth connection of the third router valve 5.3 through a further reduction valve 5.4, the second connection of the third router valve 5.3 is fed back before the further reduction valve 5.4. On the other hand, through the reduction valve 5.5 and the pressure limiting unit 5.1, the third connection of the third router valve 5.3 is connected directly or indirectly to the feed pump 4.2 of the hydraulic power package 4 and to the other part 6.3 of the hydraulic accumulator 6.

For example the feed pump 4.2 driven by an electric motor 4.3 is sinking in the oil tank 4.1 of the hydraulic power package 4. The oil tank 4.1 can be filled up through the oil-filler unit 4.5.

The operation of the electrohydraulic barrier operating device according to the invention is described in detail in the following. As it is shown on Figure 2, where the hydraulic transmission unit 8 is constructed as a double-operated twin- piston hydraulic rotatory cylinder, this rotatory cylinder is built in the drive unit housing 1 in vertical position. The railing bar 2 with the closing bar 3 connected to it is mounted on the driving axle stub of this rotatory cylinder. The two pistons D1 and D2 of the rotatory cylinder being mounted on one axle are connected by a toothed rack F positioned in the axle line, this toothed rack F is connected to the cogged wheel FK mounted on an axle perpendicular to the toothed rack F. The linear motion of the pistons D1 and D2 results in the rotational movement of the driving axle. The quantity of oil of appropriate pressure as determined by the stroke length (90° turn of axle) and speed of the pistons D1 and D2 required for the linear motion of the pair of pistons Dl and D2 is provided by the hydraulic power package 4 through the electrohydraulic control unit 5.

The initial position, that is the open or closed position of the railing bar 2 is generated by an input command BU corresponding to the traffic situation with the help of the internal electric control and sent-back system R. It is also this system R that sends output check-back signals KV relating to the movement and the actual position of the railing bar 2 to the known railway control centre. In agreement with the usual practice at railways an input command BU (which is an electric signal) is valid until another command (electric signal) with opposite meaning is received. When it is received, the input command BU generates an electric connection through the code cylinder situated in the code-sender 9, which results in moving the railing bar 2 into the opposite position and it is kept there until the next command of opposite meaning. In agreement with the usual basic railway system the input command BU generating and maintaining the open or closed position of the railing bar 2 holds continuously.

In case of non-failed status (perfect current supply) of the electrohydraulic operating system the setting of the railing bar 2 from open (vertical) to closed (horizontal) position takes place as the following, while the hydraulic working fluid is let in through the operating input B, and it is conducted away through the operating input A of the rotatory cylinder.

Through the contact elements of the code cylinder of the code- sender 9, the external input command BU energizes the electromagnet M1 of the second router valve 5.2 and the electromagnet M3 of the third router valve 5.3. In this position the first connection and the third connection of the second router valve 5.2 are connected, so the working fluid of the required operating pressure arrives to the operating input B through the control output VB and moves the piston D2 of the ratatory cylinder. The connection between the toothed rack F and the cogged wheel FK transmits the torque to the driving axle. During this process working fluid of the same amount as it was let in through the first operating input A is let out through the first and fourth connection of the third router valve 5.3 and through the reduction valve 5.4 and the oil filter 4.4 to the oil tank 4.1.

At the end of the accelerating part of the closing movement of the railing bar 2 (determined by the specific code cylinder of the code sender 9, adjustable preferably to a displacement of 75-80°) the code sender 9 makes the current of electromagnet M3 stop, so the spring R3 of the third router valve 5.3 switches the returning oil to the reduction valve 5.5 so the oil gets to the oil tank 4.1. The hydraulic resistance of reduction valve 5.5 is preferably much larger than the hydraulic resistance of reduction valve 5.4, so it damps the movement of the railing bar 2 that has been accelerated up to this moment, so the "arriving velocity"of the closing bar 3 is reduced. This velocity can be adjusted by the appropriate calibration of the reduction valves 5.4 and 5.5.

In the course of the above procedure the pressure of the compressed nitrogen gas in one part 6.2 of the hydraulic accumulator 6 decreases adiabatically, which is sensed by baroswitch 5.6. At the appropriately adjusted lower limiting value the electric motor 4.3 is switched on and the feed pump 4.2 fills up the part 6.2 (nitrogen space) of the hydraulic accumulator 6 to the upper limiting pressure determined by baroswitch 5.6, than the electric motor 4.3 switches off. As a result, the hydraulic accumulator 6 is ready again to perform a further cycle or cycles.

In case if the pressure of the nitrogen in part 6.2 of the hydraulic accumulator 6 is at the lower limiting value, the electric motor 4.3 switched on and the feed pump 4.2 works directly to the second router valve 5.2, charging partly the hydraulic accumulator 6 at the same time. At the end of the cycle of setting the barrier from open to closed position (or the opposite cycle) the charging of the hydraulic accumulator 6 is completed, and the baroswitch 5.6 switches the electric motor 4.3 off. At the end of the given cycle the code-sender 9 provides for the no-voltage state of the electromagnets MI and M3 of the second router valve 5.2 and the third router valve 5.3, the springs R1 and R2 establish the closing position afterwards.

In the course of setting the railing bar 2 from closed (horizontal) to open (vertical) position the working fluid is let in through the first operating input A, and it is let out through the second operating input B. The whole controlling procedure is the same as described above, with the difference that in this case the electromagnet M2 of the second router valve 5.2 is energized and so the third connection of the second router valve 5.2 becomes active through its first connection, so the required working fluid appears at the first control output VA. The working fluid is conducted to the third router valve 5.3 through the second operating input B, the second control output VB and the second connection of the second router valve 5.2.

The hydraulic system is protected against excess pressure by the pressure limiting unit 5.1.

In the followings we describe the situation when operating trouble takes place, so there is no current supply. In this case automatic safety closing procedure takes place. If the railing bar 2 is in open position and the current stops, than the electromagnet M4 of the router valve 7 operated by an electromagnet opening in case of current failure releases, and through the connection established by spring R4 the working fluid flows to the third operating input B'through the first back-pressure valve V1, and as a result the barrier closes.

As there is no current supply, the electromagnet M2 of the second router valve 5.2 is inactive, so spring R2 closes the way between control output VB and the second connection of router valve 5.2, while the first back-pressure valve V1 closes the way to router valve 7, so no unauthorised person can move the barrier manually. So in our solution this automatic safety blocking is established by the operating trouble, that is, the current failure. This blocked position can be released only by an authorised operating person preferably with a special tool.

When the operating trouble is over the electromagnet M4 of the router valve 7 pulls and restores the normal position.

In the case of normal operation the third and first connections of router valve 7 is open through the second back-pressure valve V2, in this case it is the third back-pressure valve V3 that prevents backflow.

Let us examine the special case when the input command BU arrives in order, but some other failure, e. g. failure of the electric motor 4.3 or the feed pump 4.2 hinders normal operation. It is to be mentioned here that the probability of mechanical failures of the electrohydraulic barrier operating device is extremely low. In case if the input command BU is present, the electric control and sent-back system R sends a signal to the railway control centre in case of accidental failure of the electric motor 4.3.

In case of any kind of failure of the hydraulic power package 4 the back-pressure valve V4 disconnects the hydraulic power package 4 from the electrohydraulic control unit 5, in this case the operating role of the hydraulic power package 4 is entirely taken over by the hydraulic accumulator 6. The capacity of the hydraulic accumulator 6 is enough to complete the possible cycle to be performed as mentioned above, and also, the device is capable to perform further cycles from resting position corresponding to two-four input commands BU.

The capacity of the hydraulic accumulator 6 can be varied if. necessary, and the security can be further improved by doubling the hydraulic accumulator 6.

In case if the input command BU is present and there is some kind of special failure in the system as mentioned above, the railway control centre (dispatch office) can deliberately stop the current supply of the electrohydraulic barrier operating device initiating this way the above mentioned situation resulting in the blocked closed position of the barrier until the failure is eliminated. In this case only an authorised operating person can operate the barrier manually making temporary crossing possible depending on the actual traffic situation.

Based on the above it is obvious that the technology of securing the crossings of roads and railways can be solved at a higher level with this barrier operating device as compared to the presently known solutions. This fact is supported by the preliminary qualification handed out by the Traffic Automatics Department of Budapest University of Technology.