The subject of the invention is The system for controlling of the executive assembly of the hydraulic brakes, especially of the automotive of light and medium size of gooseneck trailers and trailers.

Brake systems known at the automotive market for large semi-trailers and trailers are mostly based on pneumatic subassemblies, that control the operation of drum mechanical brakes or their pneumatic brake system activates pneumatic-membrane cylinders of two-sided operation that control the operation of hydraulic brakes.

The pneumatic brake systems consist among other things of Electric Brake System (EBS) controls, that depending on the air pressure variation in the vehicle brake system, control the operation of modern pneumatic as well as pneumatic and hydraulic brakes in semi-trailers and trailers. Usually, EBS controls are linked via two lines of control signals i.e. pneumatic and electric. The pneumatic line controls the pneumatic brakes, and the electronic system of EBS controls additionally considers current weight of the semi-trailer / trailer (signal from the air bag suspension system) and data from ABS system sensors. Based on the analysis of signals sent through these sensors that are installed in the brake mechanisms disks of individual wheel of towed vehicle, EBS control controls the operation of the brakes on the right or left side adequately. Signals from the electric control line are used exclusively for the control of connection correctness between the truck and towed vehicle. In case of electric signal decay in the electric line, e.g. due to disconnection of the vehicles, the electronic system of EBS control activates the emergency brake system of the semi-trailer or trailer.

In case of EBS controls, known at the market, e.g. of WABCO make, when using the electric control line signals, it is not possible to control the operation of EBS control, thus operation of the pneumatic brakes in a manner that corresponds to the operation of brake systems in tractor or truck.

Known designs of simplified brake systems in smaller trailers are based on either dangerous brakes of inertial type (overrunning) or in case of average size semi-trailers or trailers, pneumatic systems of analogical operation to larger sets of road vehicles.

In case of a vehicle towing a trailer with overrunning brakes, except the ball coupling and conductor controlling the trailer lights, there are no other elements of brake system installed, what would be a significant advantage of such solution, but poor effectiveness of brakes operation causes that these trailers endanger safety and life of the driver and of other drivers.

Semi-trailer or trailer with pneumatic brakes necessitates installation in the vehicle of relatively large elements of the pneumatic brake system such as compressor, air tank, pneumatic hoses, valves, etc. Air compressor of this brake system operates in practically continuous mode, hence it also continuously draws engine energy necessary for its operation. The remaining elements of the pneumatic brake system take up a lot of space in the vehicle, especially a-few-dozen-litre compressed air tanks.

The system according to invention is deprived of difficulties related to installation of the compressed air tanks, compressors, etc. and enables using the electric control line only, to control the pneumatic and hydraulic executive assembly and operation of the hydraulic brakes.

According to the subject matter of invention, the system comprises the pressure transmitters connected to the vehicle brake pump, connected via electric wires through the comparator with electric-pneumatic proportional valve, and the inlet of the proportional valve is connected by means of pneumatic hose with the air tank, and the outlet of the proportional valve is connected by means of pneumatic hose with the first inlet of the EBS control, at the same time convertor of the air bag suspension system is connected by means of pneumatic hose with the second outlet of the EBS control, as well as the ABS sensor is connected by means of electric wire with the third inlet of the EBS control, while the outlets of the EBS control are connected by means of pneumatic hoses with air-hydraulic actuators, and the outlets of the air-hydraulic actuators are connected with hydraulic brakes of the semi-trailer or trailer.

In the system, each of the pressure transmitters is preferably installed from below on the T-connector, that is mounted on the vehicle brake pump, at the top part the T-connector comprises the air-bleeding valve, and at the side wall the T-connector comprises the union bolt socket for one of two circuits of the hydraulic pump.

Moreover the system comprises two compressors connected by means of separate pneumatic hoses with one-way valves and then with the air tank, and in each of the compressors is mounted the cooling hose of which other end is connected by means of pneumatic hose with one-way . valve and with air tank,

In the system, the electric-pneumatic proportional valve is preferably connected by means of short pneumatic hoses with EBS control and similarly, by means of short pneumatic hoses the other elements: compressors, one-way valves, air tank and air-hydraulic actuators are connected.

In one variant of the system of invention, the comparator comprises the outlet of the current signal. In the other variant of the system of invention, the comparator comprises the outlet of the voltage signal.

In the solution of invention, wherein the hydraulic pressure transmitters are connected via electric wires with the voltage or current signals comparator that analyzes both signals and sends one selected signal, when both signals are of the same value or in case the signals differ, it sends the signal of higher value of voltage or current.

The system according to the invention is also characterized in that the cooling hose, specially formed of copper tube is directly connected to compressed air socket of the compressor, and the other end is connected to the air hose.

The system according to the invention is also characterized in that the electric-pneumatic proportional valve is connected via short pneumatic hose with EBS control, alike the remaining elements: air compressors, valves, air tank, air-hydraulic actuators.

Structure of system according to the invention has very compact construction and the reaction time of the system is shorter by half and amounts about 0.3 s comparing to the admissible reaction time that do not exceed 0.6 s. Very compact design causes that time of transferring the electric signal as well as corresponding changes of pressure in the electric-pneumatic proportional valve are sent much quicker to EBS control, pneumatic and hydraulic transmitters and to hydraulic brakes of the semi-trailer and trailer. Moreover, installation of two independently operating air compressors influence significantly the reduction of time needed to fill the air tank with air and in case of fault of one of the compressors, provides continuous operation of the brake system, without the need to immediately repair and replace the defective compressor. Similarly, the installation of voltage or current signals comparator provides either in case of fault of one of the hydraulic circuits of the vehicles hydraulic system or fault of the pressure transmitter, the control of the electric signal of the electric-pneumatic proportional valve and correct functioning of the whole brake system.

The system enables major improvement of safety related to utilization of transportation sets within the sector of light and average semi-trailers and trailers and reduces the risk of accidents caused by poor effectiveness of overrunning inertial brakes, especially during driving under severe weather conditions on slippery and icy road. New brake system should also influence the improvement of agricultural transportation safety, especially related to forest transportation, because it is frequent case that forest trailers of maximum authorized total mass up to 10-12 t are not equipped with any kind of brakes.

The subject of the invention is presented in the embodiment on the drawing, where the Fig. 1 shows block diagram of full version of the system with two pressure transmitters and voltage or current signals comparator as well as compressors with additional cooling segments. In the diagram, air hoses are identified with double line, electric wires with broken line and hydraulic hoses with full line.

The system consists of pressure transmitters 1 installed in the circuits of the vehicle brake pump 2, electric wire 3 connecting the electric-pneumatic proportional valve 4 connected by means of pneumatic hoses 5 with the air tank 6 and EBS control 7. EBS control 7 is connected via pneumatic hoses 5 with air- hydraulic actuator 8 and the air bag suspension system 9 of the semi-trailer and trailer. The air-hydraulic actuators 8 are connected with hydraulic brakes 11 of the semi-trailer and trailer via hydraulic hoses 10. The wheel disks are equipped with ABS sensors 12 that are connected with EBS control 7 via ABS wire 13. Two, electrically supplied compressors 14, via pneumatic hoses 5 are connected to one-way valves 15 and further to the air tank 6. In the full executive option, the electric-pneumatic system consists of two pressure transmitters 1 that are installed on T-connectors 17 screwed directly to the body of the vehicle brake pump 2. Connectors 17 in their top part, are equipped with air-bleeding valves 18 and with union bolt sockets 19 on the side wall to connect the brake circuits of the vehicle. The pressure transmitters 1 are connected via electric wires 3 with the voltage or current signals comparator 16 which is connected with electric-pneumatic proportional valve 4 by means of electric wire 3. Moreover, cooling hoses 20 are installed in the compressed air circuits of the compressors 14. In order to unequivocally present the nature of the invention, the block diagrams do not include connections of fuses, relays, system operation status indicators, control sockets, computer sockets, valves, etc.

The system according to the invention, consists of a part of the system installed in the vehicle and section installed in the semi-trailer/trailer. In the vehicle, the brake pump 2 is equipped with two pressure transmitters 1 , voltage or current signals comparator 16 next to them and electric circuit 3 connecting the comparator 16 with the connection socket of the semi-trailer/trailer.

Trailer is equipped with: electric wire 3 connected with a plug and electric-pneumatic proportional valve 4 and other elements: two compressors 14, one-way valves 15, air tank 6, EBS control 7, air-hydraulic actuators 8.

Method of operation of the system is as follows: drivers depresses brake pedal that activates the brake pump 2. Hydraulic (brake) fluid pressure increases in the brake pump 2, it is compressed and acts on the elements inserted in both brake circuits of the vehicle, including pressure transmitters 1 preferably installed from below (easiness of venting) on special T-connectors 17. The pressure transmitters 1 , proportionally to the hydraulic pressure changes of the brake pump 2, change instantaneous pressures into electric signals, voltage or current 4-20 mA, and send them to the comparator 16. The comparator 16 compares both signals and if they are identical - selects one of them and sends to the electric pneumatic proportional valve 4, or if they differ, it sends the one of higher value. The comparator 16 selects the higher control signal - what is an important and beneficial feature of the solution, because it secures correct operation of the system part that is installed in the semi-trailer or trailer, e.g. in case of fault of one of the vehicle brake system circuits or in case of damage of one of the pressure transmitters 1 that are installed on the vehicle brake pump 2.

The selection of signals in the comparator 6, is of important meaning for the correct operation of the system in case of controlling the current signal of the electric-pneumatic proportional valve 4.

In the electric-pneumatic proportional valve 4, the electric signal is converted to proportional value of air pressure, variations of which control the operation of EBS control 7 and air-hydraulic actuators 8 and hydraulic brakes 11.

Advantage of the solution according to the invention consists in innovatively configured electronic, pneumatic and hydraulic subassemblies available at the market and their combination. Because of that, in the vehicle the reliable electric control of the electric-pneumatic proportional valve 4 operation is enabled, thus EBS control 7, air-hydraulic actuators 8 and hydraulic brakes 11 of light and average size semi-trailers and trailers of maximum authorised mass up to 10 1. Application of cooling hoses 20 in the circuits of the compressors 14, protects the pneumatic hoses against overheating and depressurization, similarly, independent connection of the compressors with the air tank using one-way valves significantly influences the reliability improvement and operation safety level of the whole brake system. Moreover, application of short pneumatic hoses, that connect all pneumatic elements enables obtaining not only compact design of the system installed in the semi-trailer / trailer but also much shorter response times of the system - from depressing the brake pedal by the driver until obtaining proper hydraulic pressure in the brakes.

Comparing to inertial systems, the new control system represents much better, effective and safe solution; and in relation to pneumatic systems, it is characterized by significant savings of energy necessary to drive the compressors.