FR2640565A3 - Hydraulic braking system for agriculture trailers - Google Patents

Abstract

a) Hydraulic braking system for agriculture trailers pulled by tractors provided with a hydraulic braking system. b) Hydraulic system characterised in that it comprises: - a hydraulically controlled member 5 determining the braking action or the action for releasing the braking on a brake 3 of the trailer 1; - a trailer brake valve 31 which allows the brake 3 of the trailer 1 to be controlled by actuating the service brake of the tractor 2; - a hydraulic installation installed between the valve 31 and the member 5; and - an electrical device 61 and 62 capable of actuating a parking brake 4 of the tractor 2, so as to control the brake 3 of the trailer 1, by means of the hydraulic installation and of the member 5. c) The invention relates to a hydraulic braking system for agricultural trailers pulled by tractors provided with a hydraulic braking system.

Description

"Hydraulic braking system for agricultural trailers towed by tractors fitted with a hydraulic braking system"
The invention relates to a hydraulic braking system for agricultural trailers towed by tractors provided with a hydraulic braking system.

 As is known, there is currently provision in agricultural trailers for service braking controlled by the tractor brakes and for parking braking actuated by mechanical systems controllable from the ground.

 The agricultural trailer is not subjected to the actual braking action when the parking brake is actuated in the tractor or when, for any reason, the hydraulic connection between the tractor and the trailer itself is interrupted. Thus, as is obvious, there can be drawbacks in certain conditions in which the trailer can be found; one thinks for example of a stop along a slope or an interruption, even as a result of breakage, of the mechanical connection of the traction or of the hydraulic connection.

 The object of the present invention is to provide a hydraulic braking system for agricultural trailers which is free from the drawbacks mentioned and which allows the control of safe and correct braking of the trailer, directly from the tractor.

 Other objects and advantages of the present invention will be highlighted in the description which follows.

On the basis of the present invention, there is provided a hydraulic braking system for agricultural trailers towed by tractors, characterized by comprising - a hydraulically operated member, in which is
likely to move a pin connected to a
brake device of said trailer so as to
what, when said pin moves in a
sense, a braking action is determined and,
when it moves in the opposite direction,
a release action of the brake is determined
age of said trailer; - a trailer brake valve which allows
control of said member to perform, on said re
morque, a braking action when a
service brake device of said tractor - a hydraulic installation, installed between said
valve and said member; and - an electrical device capable of actuating a brake
parking said tractor, to control
said brake device of said trailer, at
by means of said hydraulic installation and said
organ.

According to another characteristic of the invention, said member comprises - a first bucket body, provided with a wall of
bottom and cover - a second body, installed inside said
first body - first spring means capable of
press said second body towards said journal and
well to press outward from said first
body said pin, so that these
determine the braking action of said
brake on said trailer - second spring means, capable of
oppose said first spring means; and - a chamber defined inside said first
body and communicating with said hy facility
hydraulics, so that a fluid introduction
pressurized in this same chamber produces a
opposition to the first spring means, for
perform a brake release action on
said trailer.

According to another characteristic of the invention, said hydraulic installation comprises - a first hydraulic communication line
between said chamber and a first mouth of
said valve - a second hydraulic communication line
between said first pipe and a second nozzle
entry of said valve and along
which is installed a first solenoid valve
normally closed - a third hydraulic line along
which is installed a pump and which starts from a
fluid reservoir for connection in said
second pipe, between said first solenoid valve
and said second mouth - a fourth hydraulic communication line
between a third discharge mouth of said
valve and said tank and along which
a one-way valve, calibrated at
a predetermined pressure, to allow the
discharge to said reservoir in the case of a
pressure greater than the predetermined pressure a fifth hydraulic line, derived from ladi
fourth line, a little downstream of said
third mouth, along which is
installed a second solenoid valve normally or
green, which allows the discharge of the fluid towards said
reservoir - a first rod, installed in said valve and
likely to move axially under the action
pressurized fluid, to achieve, in a posi
operation, the hydraulic connection between
said second mouthpiece and a fourth mouthpiece
re output to a user or said third
discharge mouth, and, in a second position,
the previous link and the hydraulic link
between said second mouth and said first
mouth; and a second rod installed in said valve,
likely to move axially under the action
of an order implemented by actuation of the
brake device of said tractor and allowing, in
a first operating position, the communi
cation, towards said third discharge mouth
ge, said first mouth and said
second mouth, and, in a second position,
closing these communications.

According to another characteristic, said electrical device comprises - a first relay having the electromagnet itself
even, which allows, if de-energized, to achieve a
electrical contact determining the electrical supply
stick of said second solenoid valve, for provo
quer the interruption of flow along the
fifth line and that determines the power
electric to a common terminal of a second
relay - said second relay presenting the electromagnet
even which allows, if excited, to achieve a
electrical contact between said common terminal and a
second terminal from which a supply line is derived
tion for said first solenoid valve - a switch installed on the supply line
of the electromagnet of said first relay and control
due to the actuation of said parking brake
ment, so as to allow said feeding
electric when the latter performs its action of
braking in said tractor; and - a pressure switch installed along the feed line
tation of the electromagnet of said second relay and
likely to allow said electrical supply
tackle when, by means of a sixth pipe
hydraulic, it occurs along said first
re conduct a pressure value below
the one for which the said unidi valve is tared
rational.

 For a better understanding, the present invention is now described and explained with reference to one of its preferred embodiments, made by way of nonlimiting example and with reference to the accompanying drawing, in which a braking system for a trailer is shown. agricultural 1 towed by a tractor 2. For the sake of simplicity, the trailer and the tractor are represented very schematically, by simple dotted rectangles. The trailer 1 is provided with a brake 3 also shown diagrammatically by a jaw which, in operation, is applied in correspondence with the wheels of the trailer 1.

 The braking system which is the subject of the present invention makes it possible to brake the trailer 1 and thus supply the service brake of the tractor, by means of the actuation of a parking brake 4 of the tractor, and , when, for any reason, there is a break in the hydraulic connection between the tractor and a brake control member 5 installed in the trailer 1.

 The member 5 comprises a bucket member 6 having a cylindrical side wall 7, a bottom wall 8 and provided with a cover 11. Inside the body 6 is installed a second bucket body 12, capable of moving axially and having a bottom wall 13, a cylinder side wall 14 extending towards the cover 11, and an annular appendage 15 which starts from the edge of the wall 14. Between this appendage 15 and the bottom wall 8 of the body 6 is installed a prestressed spring 16. Inside the body 6, through the cover 11, extends part of a pin 17 capable of moving axially. This pin 17 is provided with a head 18 which, in service, presses the bottom wall 13 of the body 12 on the bottom wall 8 of the body 6. Between the head 18 and the internal face of the cover 11, a second prestressed spring 21. Inside the body 6, the space between the body 12 and the internal face of the cover 11 defines a chamber 22, into which, through a hole 23 made in the cover 11, the oil arrives under pressure. The displacement in one direction or in the opposite direction of the pin 17 determines the actuation or not of the brake 3. In particular, when the pin 17 moves towards the outside of the body 6, there is control of the braking action of the brake 3, and when the pin moves towards the inside of the body 6, this braking action is interrupted. Because the spring 16 has a prestressing value which is higher than that of the spring 21, the trailer 1 is normally braked and thus remains braked until a fluid is introduced inside the chamber 22 whose pressure reaches a value which overcomes the action of the spring 16.

The tractor 2 is provided with a valve 31 for controlling the trailer brake, which is of known type. In particular, the valve 31 illustrated in the figure is produced by the German company Robert
Bosch GmbH which mentions it in its own catalogs under the reference number 0538008300. A similar valve is produced by the applicant and is fully described in the patent application, naturally issued by the application, filed in Italy on December 18, 1980, under metro 68935A / 80. We will therefore refrain from describing this valve 31 in detail, providing only a few indications thereof.

 The valve 31 comprises an inlet mouth 32 of a seat along which acts a rod 33 capable of assuming different axial positions in which there can be communication from the mouth 32 with an outlet mouth 34 or with a mouth of outlet 35, in the latter case, through a one-way valve 36. The oil can flow through the rod 33 to go to a discharge mouth 37. In correspondence with the mouth 35, a seat is produced along which acts a second rod 38, capable of assuming different axial positions in which there is closure or opening of the hydraulic communication between the discharge mouth 37 and on the one hand the mouth 35 and on the other hand the mouth 32, in the latter case via the passage of oil along the rod 33. The axial position of the rod 33 is controlled by the flow of oil under pressure through the mouth 32, while that the posit axial ion of the rod 38 is controlled by the flow of pressurized oil through the mouth 35 and by the axial position of a small piston 41, belonging to a pilot block 42, movable under the action of a pressurized oil flow which arrives in the small block 42, passing through a line 43, coming from the main cylinders of the hydraulic brakes of the tractor 2.

 Referring to the attached drawing, the hydraulic system which is the subject of the present invention comprises a first hydraulic pipe 45 for connection between the mouth 35 and the hole 23 and a second hydraulic discharge pipe 46 starting from the mouth 37 and joining a reservoir 47. Along the pipe 45 is installed a hydraulic seal 48 which makes it possible to interrupt this hydraulic connection when the trailer 1 has to be detached from the tractor -2.

Along the line 46 is installed a one-way valve 51 which is calibrated at a pressure value of approximately 10 bars, value for which this valve allows the discharge to the reservoir 47 when the oil is subjected to a pressure of value greater than the taring value. Upstream of the valve 51, it leaves from the pipe 46 a third pipe 52 which joins the reservoir 47 and along which is installed a first normally open solenoid valve 53. Upstream of the seal 48, it leaves from the pipe 45 a fourth hydraulic pipe 54 which will be introduced into the mouth 32 and along which is installed a second normally closed solenoid valve 55. Between the solenoid valve 55 and the mouth 32, in line 54, a fifth hydraulic line 56 is connected, plunging into the tank 47 and along which are installed a filter 57 and a pump 58; the latter is normally actuated via a PTO of the tractor engine 2.

 The braking system further comprises an electrical device for controlling the solenoid valves 53 and 55 which has two relays 61 and 62, a switch 63 actuable by the parking brake 4 and a pressure switch 64 having the functions which will be described below. An electric cable 65 going to supply the electromagnet of the relay 61 and along which the switch 63 is installed starts from the positive pole of a battery of the tractor 2. The switch 63 is closed when the parking brake 4 is applied and so when the lever of the latter is pulled into the position in which the braking is carried out. The relay 61 has a central terminal 66 which is connected, by an electric cable 67, to the positive pole of the battery, and has two terminals 68 and 71, whose terminal 68 is free and is therefore not connected to any electrical member and whose terminal 71 supplies the solenoid valve 53 via an electric cable 72 and is connected to a central terminal 74 of the relay 62 , by means of an electric cable 73. When the switch 63 is closed, there is supply of the electromagnet of the relay 61 which makes the electrical contact between the terminals 66 and 68. The relay 62 also has two terminals 75 and 76, of which terminal 75 is of the type of terminal 68, and terminal 76 supplies the solenoid valve 55 by means of a cable 77 and supplies, by means of an electric cable 78, an indicator light 81 capable of indicate that the value of the oil pressure along line 45 is less than 10 bars. An additional electrical cable 82 supplying the electromagnet of relay 62 by the positive pole of the battery. Along this electric cable 82 is installed the pressure switch 64 which is none other than a switch which is closed below a predetermined value of the pressure of the oil which circulates along the pipe 45. This value of In this example, the pressure corresponds to 10 bars. To take the pressure from the pipe 45, upstream of the seal 48, a pipe 83 is brought to the pressure switch 64. When, along the pipe 45, the oil is located at a pressure of less than 10 bars, the pressure switch 64 makes it possible to supply the electrical power to the electromagnet of the relay 62 which determines the electrical contact between the terminals 74 and 76, which causes the power to the solenoid valve 55 and indicator light 81.

 In service, by pulling the parking brake lever 4, the switch 63 is closed, allowing the electromagnet of the relay 61 to be supplied. The latter interrupts the electrical contact between the terminals 66 and 71 by interrupting the passage of electrical energy to the terminal 74 of the relay 62 and to the solenoid valve 53. No longer being energized, the latter allows the passage of the oil along the line 52, towards the discharge. Inside the valve 31 is made the hydraulic communication between the mouth 35 and the discharge mouth 37, which causes the discharge in the reservoir 45 of the oil present inside the chamber 22, in passing through the pipe 45, the mouth 35, the mouth 37, the start of the pipe 46 and the pipe 52. The lack of oil in the chamber 22 allows the spring 16 to overcome the spring 21 and to determine the outward movement of the body 12 and thus of the journal 17. By its movement, the latter determines the braking action of the brake 3.

 Due to the pressure drop occurring along line 45 at the moment when the oil discharge occurs, the pressure switch 64 closes its own switch allowing the electrical supply of the electromagnet of relay 62 which determines the electrical contact between terminals 74 and 76.

The solenoid valve 55 is however not yet energized insofar as the terminal 74 of the relay 62 is not yet connected by means of the relay 61 to the positive pole of the battery. The solenoid valve 55 thus also closes the pipe 54 between the pump 58 and the connection to the pipe 45. The pump 58 thus introduces oil into the mouth 32 of the valve 31. In this state, the mouth 32 is in hydraulic communication with mouth 34, from which leaves a hydraulic line 84 by means of which it is possible to supply other hydraulic members of the tractor 2 or of the trailer 1, for example an elevator.

 For the tractor to start advancing, it is first necessary to press down on the parking brake lever 4. By doing so, you open the switch 63 which interrupts the electrical supply to the electro -magnet of relay 61 which is thus de-energized. This causes electrical contact between the terminals 66 and 71 of the relay 61 and thus determines the supply of the solenoid valve 53, through this same relay 61, and the supply of the solenoid valve 55 via the relay 62. We remember that the latter was already predisposed to be supplied during the previous maneuver by the pressure switch 64 which does not yet undergo in the pipe 45 a pressure greater than 10 bars. The solenoid valve 53 determines the closing of the line 52 going to the reservoir 47. Because, along the lines 54 and 45, the oil is in the presence of pressure drops lower than those encountered during its flow to the line 84, it more easily takes the path of the member 5, thus entering line 45. In the latter, the oil finds two paths, one going towards the chamber 22 and the other going towards the the mouth 35 of the valve 31 which is still in hydraulic communication with the discharge mouth 37. However, the discharge to the reservoir 47 taking place along the line 52 is interrupted by the solenoid valve 53 and, along the line 46, it is interrupted by the valve 51, which produces a rapid filling of the chamber 22. Meanwhile, due to the reduced flow occurring towards the mouth 32, the rod 33 also performs the hydraulic communication between mouth 32 and mouth aperture 35, passing through valve 36, which also causes pressurized oil to flow through mouth 35, to chamber 22, where pressurized oil will assist spring 21 to overcome the spring 16, thereby determining the inward movement of the member 5 of the pin 17, by deactivating the brake 3 of the trailer 1.

 When, along the line 45, there is a pressure which is greater than 10 bars, the pressure switch 64 intervenes by opening the electrical connection with the electromagnet of the relay 62 which determines the electrical contact between the clean terminals 74 and 75, by interrupting the supply to the solenoid valve 55. The latter returns to the closed position, closing the hydraulic communication between the pump 58 and the chamber 22. In the latter, the oil remains, by determining the the release action of the brake 3 and the excess pressure is discharged by the valve 51, while still being in hydraulic communication with one another, with the mouths 35 and 37.

A pressure balance is thus created along the rod 33. The pump 58 is forced to make the oil flow under pressure towards the mouth 34 and thus towards a user.

 When the hydraulic brakes of the tractor 2 are actuated, pressurized oil pushing the small piston 41 towards the rod 38 enters, passing through the pipe 43, into the small pilot block 42.

The rod 38 moves towards the mouth 35, thereby interrupting the communication between the latter and the discharge mouth 37. In addition, the rod 38 obstructs the flow of oil inside the rod 33, towards the mouth 37. This displacement oil not finding passage to the discharge mouth 37 causes the axial displacement of the rod 33 towards the mouth 32 and thus the hydraulic communication between the latter and the mouth 35. Naturally, this communication allows a constant flow of flow insofar as a calibrated orifice is installed along the rod 33. In the mouth 35, a pressure is thus created which acts on a calibrated surface of the rod 38, in opposition to the pressure exerted by the small piston 41. When the action of pressure tends to exceed the force which acts on the small piston 41, the rod 38 moves towards the small piston 41, until equilibrium is reached bre of pressures, opening to insi the mouth of the displacement oil along the rod 33, towards the mouth 37, but now isolated the communication between the mouth 35 and the mouth 37. The aforementioned displacement oil finding passage, the rod 33 returns to close off the passage between the mouths 32 and 35. To increase the braking action on the trailer 1, it is necessary to further increase the pressure of the small piston 41 on the rod 38 to thus find a new balance.

 The numerous advantages brought by the realization of the present invention appear as obvious in the light of the description above.

 In particular, the braking action of the brake 3 of the trailer 1 is manifested by actuating the parking brake 4, by actuating the normal brake of the tractor 2 and by interrupting, for any reason, the hydraulic connection with the member 5 .

As is obvious with the braking system described above, correct and efficient braking of the trailer 1 is carried out directly from the driving position of the tractor 2 and the level of safety for the vehicle is significantly increased. operator. All this is obtained by maintaining the connection between the service braking of the tractor 2 with the braking of the trailer 1. In addition, it should be emphasized that the chamber 22 is subject, by actuating the parking brake 4 towards the release position. braking, rapid filling and thus the system according to the invention makes it possible to maneuver quickly to disengage the brake 3 and thus to start the advancement of the tractor 2.

 Finally, it is obvious that the hydraulic and electrical components of the system are products which exist on the market and the overall installation is therefore of simple construction and of reduced production cost.

 It is finally clear that the present invention is not limited to the embodiments described and shown but that it is capable of numerous variants accessible to those skilled in the art without departing from the scope of protection of the invention.

Claims (2)

CLAIMS hydraulic and said member (5). said trailer (1), by means of said installation for controlling said brake device (3) of a parking brake (4) of said tractor (2), valve (31) and said member (5); and - an electrical device (61 and 62) capable of actuating the tractor (2) - a hydraulic installation, installed between said actuates a service brake device of said trailer (1), a braking action when controlling said member (5 ) to achieve, on said release action of the braking of said trailer (1) - a trailer brake valve (31) which allows movement in the opposite direction, a braking action is determined and, when the latter lon (17) moves in one direction, it is determined that (1), so that, when said journal connected to a brake device (3) of said trailer is likely to move a journal (17)  1 ') Hydraulic braking system for agricultural trailers (1) towed by tractors (2), characterized by comprising - a member (5) hydraulically operated, in which  said trailer (1).  perform a brake release action on  opposition to the first spring means (16), to  under pressure in this same chamber produces a  hydraulic, so that an introduction of fluid  body (6) and communicating with said installation  and - a chamber (22) defined inside said first  oppose said first spring means (16)  brake device (3) on said trailer (1) - second spring means (21), capable of  that these determine the braking action of said  mier body (6) said pin (17), so that  (17) and thus to press towards the outside of said pre  pressing said second body (12) towards said journal  first body (6) - first spring means (16) capable of  bottom (8) and a cover (11) - a second body (12), installed inside said  2-) System according to claim 1, characterized in that said member (5) comprises - a first bucket body (6), provided with a wall of  communications.  and, in a second position, the shutter of these  mouth (35) and said second mouth (32),  discharge mouth (37), of said first em  communication, towards said third  allowing, in a first operating position  brake device of said tractor (2) and  the action of a command implemented by the action  (31), capable of moving axially under  re (35); and - a second rod (38) installed in said valve  second mouth (32) and said first mouth  previous and the hydraulic connection between said  (37), and, in a second position, the connection  tor or said third discharge mouth  fourth outlet mouth (34) to a user  that between said second mouth (32) and a  an operating position, the hydraulic link  the action of the fluid under pressure, to achieve, in  pe and likely to move axially under  towards said tank (47) - a first rod (33), installed in said valve  normally open, which allows the discharge of the fluid  a second solenoid valve (53) is installed  said third mouth (37), along which  said fourth pipe (46), slightly downstream of  at the predetermined pressure - a fifth hydraulic line (52), derived from  reservoir (47) in the case of higher pressure  completed, to allow discharge to said  unidirectional (51)), calibrated to a predefined pressure  and along which is installed a valve  (37) of said valve (31) and said tank (47)  cation between a third discharge mouth  chure (32) - a fourth hydraulic line (46) of communi  first solenoid valve (55) and said second nozzle  in said second pipe (54), between said  a fluid reservoir (47) for connection  which is installed a pump (58) and which leaves  first solenoid valve (55) normally closed; - a third hydraulic line (56) along  (31) and along which is installed a  second inlet mouth (32) of said valve  tion between said first pipe (45) and a  mouth (35) of said valve (31) - a second hydraulic line (54) of communica  tion between said chamber (22) and a first  36) System according to claim 2, characterized in that said hydraulic installation comprises - a first hydraulic line (45) of communica  one-way valve (51).  lower than that for which is tared said  said first line (45) a pressure value  hydraulic line (83), it occurs along  electrical power when, by means of a sixth  lais (62) and capable of allowing said feed  supply of the electromagnet of said second re  its braking action in said tractor (2); and - a pressure switch (64) installed along the line  power supply when the latter performs  parking (4), so as to allow said  and controllable by actuation of said brake  of the electromagnet of said first relay (61)  supply for said first solenoid valve '55) - a switch (63) installed on the feed line  and a second terminal (76) from which a line is derived  electrical contact between said common terminal (74)  itself which allows, if excited, to achieve a  (74) of a second relay (62) - said second relay (62) having the electromagnet  power supply to a common terminal  the fifth line (52) and which determines  cause the flow to stop along  electric of said second solenoid valve (53), for  be an electrical contact determining the power supply  himself, which allows, if he is de-energized, to realize  4e) System according to claim 3, characterized in that said electrical device comprises - a first relay (61) having the electromagnet