IT201800007776A1 - INTELLIGENT HYDRAULIC TRAILER BRAKE VALVE - Google Patents

Description

DESCRIPTION

of the patent for industrial invention entitled:

"INTELLIGENT HYDRAULIC TRAILER BRAKE VALVE"

TECHNICAL FIELD

The present invention relates to a brake valve, in particular an intelligent hydraulic trailer brake valve for any type of vehicle with a tractor-trailer system, such as heavy or light tractors.

BACKGROUND OF THE INVENTION

Tractors are usually used to tow a trailer of any type and weight depending on the power of the tractor engine.

The braking of the tractor-trailer system can lead, under certain conditions, to a multiplicity of dangerous phenomena, eg. on a slope, on ice, in the event of failure of the hydraulic systems or in the event of improper braking. One of these phenomena is the so-called "Jack-Knife", in which the braking imparted by the user is not adequate to brake the trailer, which would hit the tractor until both close together around the coupling swivel to the trailer like a pocket knife lock.

To solve this problem, it is known to provide a so-called “intelligent hydraulic trailer brake valve” which is configured to control the braking of the trailer in order to avoid the “Jack-Knife” phenomenon.

These intelligent trailer brake valves are pneumatic valves that allow, under certain conditions, the control of the trailer brake in prevalence with respect to the user's control via the tractor pedals. This is necessary to control the deceleration of the trailer in order to avoid the “Jack-Knife”.

However, such an intelligent trailer brake valve requires a dedicated pneumatic control circuit and a dedicated electronic control system, so they are expensive, and the associated pneumatic systems are bulky. Furthermore, not all vehicles are equipped with pneumatic systems.

Therefore, there is a need to provide an intelligent tractor brake valve that can be used in a wide range of vehicles.

An object of the present invention is to satisfy the aforementioned needs in an optimized and cost-effective way.

SUMMARY OF THE INVENTION

The aforementioned object is achieved by an intelligent hydraulic trailer brake valve as claimed in the accompanying series of claims.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the present invention, a preferred embodiment is described below, by way of non-limiting example, with reference to the attached drawings in which:

Figure 1 is a hydraulic diagram of a trailer braking system comprising an intelligent trailer brake valve according to a first embodiment of the present invention;

● figure 1A is the hydraulic diagram of figure 1 in a different operating mode;

Figure 2 is a hydraulic diagram of a trailer braking system comprising an intelligent trailer brake valve according to a second embodiment of the present invention;

● figure 2A is the hydraulic diagram of figure 2 in a different operating mode;

Figure 3 is a hydraulic diagram of a trailer braking system comprising an intelligent trailer brake valve according to a third embodiment of the present invention;

● figure 3A is the hydraulic diagram of figure 3 in a different operating mode;

Figure 4 is a graph showing the pressure values applied to a trailer brake valve by the smart tractor brake valve of the present invention as a function of a pedal brake pressure; and ● Figure 5 is an enlarged portion of an element of the hydraulic diagram of the intelligent tractor brake valve of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

According to Figures 1, 2 and 3, a trailer braking system 1 is described comprising braking actuation means such as a pair of main cylinders 2, in particular left main cylinders 2a and right 2b controlled by the pressure of a corresponding pedal brake in known way, fluidly connected to a trailer brake valve 3, of any known type, and an intelligent hydraulic trailer brake valve (HITBV) 5 according to the invention, fluidly interposed between the main cylinders 2a, 2b and the valve 3 of the trailer brake.

Preferably, a logic valve 4 can be fluidly interposed upstream of the HITBV 5 and downstream of the left and right main cylinders 2a, 2b. This logic valve 4 can be configured to operate as an "and" logic function, allowing the passage of the smallest pressure signal coming from the left and right main cylinders 2a, 2b and directed to the HITBV 5. According to the invention, the HITBV 5 comprises three modules: ● a first module 6 configured to control the brake valve 3 independently of the pressure signal imparted by the main cylinders 2 to the HITBV 5;

● a second module 7 configured to control the brake valve 3 according to a preset characteristic with respect to the pressure signal received from the main cylinders 2 when the first module 6 is not engaged;

● a third module 8 configured to control braking, when the pressure signal imparted by the main cylinders 2 to the HITBV 5 is greater than a preset threshold.

As shown in the graph in figure 4, the HITBV can impart pressure to the trailer brake valve 3 following area A, a first line B and a second line C.

The first line B can represent the preset characteristic of the second module 7 according to which, when a pressure signal Pi is applied by the main cylinders 2, a directly proportional fluid pressure flow Pi 'is applied to the brake valve 3, thus following the first line B, which is essentially the bisector of the quadrant defined by the graph.

Area A is the area defined by the Pmax value, i.e. the maximum pressure flow of the fluid that can be imparted by the HITBV 5, and by the second line C and represents the possible control values that can be adjusted by the first module 6 According to module 6, when a pressure signal Pi is applied by the main cylinders 2, independent pressure flows Pi '' of the fluid can be applied to the brake valve 3, according to the conditions of the tractor-trailer system on the road.

The second line C starts from a preset threshold Pcyl_adm of the pressure signal received from the main cylinders 2 and joins the point defined by the intersection of Pmax (as mentioned, the maximum pressure flow of the fluid that can be imparted by the HITBV 5) and Pcyl_max (i.e. the maximum pressure signal that can be received from the main cylinder 2). According to this line C, when a pressure signal Pi '' 'is applied by the main cylinders 2, a value Pi <iv> is applied to the brake valve 3 by the first module 6, according to the value defined by the intersection with the line C .

In particular, all modules 6, 7 and 8 are fluidically connected, upstream from the brake valve 3, to a pilot valve 11 configured to allow the passage of the fluid flow at a higher pressure coming from these modules and directed towards the brake valve 3. In particular, the second module 7 and the third module 8 are fluidly parallel to each other between the logic valve 4 and the pilot valve 11.

The second module 1 essentially comprises the valve 12, preferably an electrically actuated ON-OFF valve, fluidly interposed on a duct 13 which fluidly connects the logic valve 4 and the pilot valve 11. The valve 12 is configured so that, if the first module 6 is functioning correctly, it is kept in the open state and therefore no fluid can flow through the duct 13 towards the pilot valve 11; on the contrary, if the first module 6 is not functioning correctly, a signal is given and the valve 12 is closed so that the fluid can flow into the pilot valve 11. The second module 7 can also comprise a non-return valve 14 fluidly interposed downstream with respect to valve 12 but upstream from pilot valve 11.

The third module 8 comprises a valve 16 fluidly interposed on a by-pass duct 15 configured to fluidly bypass the first module 7; the valve 16 is configured to receive a pressure signal from the main cylinders 2 as input and to supply as an output a corresponding pressure signal, which is a function of the received pressure signal, according to the characteristics of the second line C. Advantageously, the valve 16 is a counter-balance valve and its structure is shown in detail in figure 5.

Referring to Figure 5, a FIN flow entering valve 16 and a FOUT flow flowing out of valve 16 lead to the following equilibrium equation:

where the present constants are:

● a, b and c are the area of the passages through which the fluid is to pass;

● Y is the spring preload; And

● K is the spring stiffness applicable to an X displacement.

As long as the FIN flow pressure is less than Pcyl_adm, the valve will be closed. When this pressure FIN is greater than Pcyl_adm, making mathematical simplifications, it results

that is, the equation of a line in a 2D plane, which does not pass through the origin. It is clear that by setting appropriate values of the aforementioned constants, the inclination and / or position of this line can vary. This line is the second line C of the graph of figure 4. When FIN is equal to the maximum of the pedal braking, then FOUT will be equal to Pmax.

According to a first embodiment of the present invention, particularly dedicated to vehicles in which the transmission oil is separated from the brake oil and shown in Figure 1, the first module 6 comprises a first valve 17, an intensifier 18 and a second valve 19, in series with respect to each other / a. In particular, the first valve 17 is fluidly interposed between a source P of pressurized fluid and the intensifier 18, the intensifier 18 is interposed between the first valve 17 and the second valve 19 and the latter is fluidly interposed between the intensifier 18 and pilot valve 11.

In greater detail, the valve 17 may be an electrically actuated two-position three-way proportional valve configured to assume two positions, a first position in which the fluid can flow from the source P to the intensifier 18 through a conduit 21 and a second position in which the fluid can flow from the intensifier 18, through a conduit 21, into the drain D.

The source P is advantageously a source of transmission oil under pressure that can flow, as described above, through the valve 17 and the duct 21 in a first chamber 18a of the intensifier 18.

The intensifier 18 is of a known type and is configured to increase the pressure of the fluid between a first chamber 18a configured to house the aforementioned fluid, i.e. the transmission oil, and a second chamber 18b configured to house another fluid, i.e. brake oil, and an actuator 22 which slides tightly inside the chambers 18a and 18b so that the two aforementioned fluids cannot mix with each other. The intensifier also includes elastic means 23 housed in the second chamber 18b and configured to counterbalance the action of the fluid in the first chamber 18a against the actuator 22.

The first chamber 18a is fluidly connected through the duct 21, as stated, to the valve 17 and, by means of a duct 24, to an outlet 25; the second chamber 18b is fluidly connected to the second valve 19 by means of a conduit 27 and to a reservoir 28 of the brake oil via a further conduit 29. The reservoir 28 of the brake oil is also connected to the valve 19 by means of a respective conduit 31. Between the oil tank 28 and the second chamber 28b a non-return valve 32 can be fluidly interposed on the pipe 29.

The second valve 19 can be an electrically actuated two-position three-way valve, configured to assume two positions, a first position in which the fluid can flow from the duct 27, coming from the intensifier 18, to the pilot valve 11 through a duct 33 and a second position in which the fluid can flow from the duct 33 to the brake oil reservoir 28. Advantageously, the electrical actuation of the valve 19 is given by a signal received from the change in position of the valve 17; in particular, when the valve 17 is positioned so that the fluid from the source P does not flow into the intensifier 18, then the valve 19 is positioned so that the fluid can flow from the duct 33 to the brake oil reservoir 28, conversely, when the valve 17 is positioned so that the fluid from the source P flows into the intensifier 18, then the valve 19 is positioned so that the fluid flows from the intensifier 33 to the pilot valve 11 through a conduit 33.

The valves 12 and 17 are advantageously controlled by a control unit, not shown.

The operation of the first embodiment described above is as follows.

In a first operating mode of the HITBV 5 (Figure 1A), in which the first module 6 is engaged, the valve 12 is closed and the valve 17 is positioned so as to allow fluid communication between the source P of fluid under pressure and the intensifier 18; consequently to this position of the valve 17, the valve 19 is positioned so that the fluid from the intensifier 18 can flow into the pilot valve 11. In this configuration, the fluid coming from the source P passes through the valve 17 and flows into the chamber 18a of the intensifier 18, pushing the actuator 22 against the spring 23 thus increasing the pressure of the fluid in the chamber 18b, which is pushed through the duct 27 and the valve 19 into the pilot valve 11. Then, according to the value of the pressure of the fluid deriving from the pressure P, a corresponding pressure value is imparted to the trailer brake valve 3 in area A, limited by the maximum pressure Pmax and by the second line C, despite the pedal brake pressure imparted by the main cylinders 2. The pressure value P is defined by a vehicle control unit considering vehicle speed, road slope, vehicle acceleration and deceleration, mass of the trailer and other parameters as known in the art.

According to the above, the HITBV 5 guarantees the hydraulic control of the pressure imparted to the brake valve 3 in all points of area A limited by the maximum pressure Pmax and by the second line C, as shown in figure 4.

In a second operating mode of the HITBV 5, in which the first module 6 is not engaged, the valve 12 is engaged and therefore the user can control the brake valve 3 thanks to the pressure of the foot brake. The pressurized fluid that comes from the logic valve 4 will pass through the valve 12 directly into the pilot valve 11 and the HITBV 5 will therefore have a characteristic corresponding to the first line B.

In parallel with the operating modes described above, the third module 8, through the valve 16, detects whether the pressure signal coming from the main cylinders 2 is greater than Pcyl_adm. If this pressure is lower, the valve 16 is closed, if this pressure is higher, a flow at a pressure according to the second line C can flow into the pilot valve 11. If this flow is greater than the flow coming from the first module 6, then this flow will pass into the brake valve 3, otherwise the fluid coming from the first module 6 will pass into the brake valve 3.

According to a second embodiment of the present invention, particularly dedicated to the vehicle that uses the same oil for the transmission and for the brake circuits at a different pressure and shown in Figure 2, the first module 6 comprises a first valve 17, an intensifier 18 and a second valve 19, in series with respect to each other. In particular, the first valve 17 is fluidly interposed between a source P of pressurized fluid and the intensifier 18, the intensifier 18 is interposed between the first valve 17 and the second valve 19 and the latter is fluidly interposed between the intensifier 18 and pilot valve 11.

In greater detail, the valve 17 may be an electrically actuated two-position three-way proportional valve configured to assume two positions, a first position in which the fluid can flow from the source P to the intensifier 18 through a conduit 21 and a second position in which the fluid can flow from the intensifier 18, through a conduit 21, into the drain D.

The source P is advantageously a source of transmission oil under pressure that can flow, as described above, through the valve 17 and the duct 21 in a first chamber 18a of the intensifier 18.

The intensifier 18 is of a known type and is configured to increase the pressure of the fluid between a first chamber 18a and a second chamber 18b configured to house an actuator 22 which flows inside the chambers 18a and 18b so that the fluid can pass through the actuator 22 from one chamber to the other, in particular from the first chamber 18a to the second chamber 18b. The intensifier also includes elastic means 23 housed in the second chamber 18b and configured to counterbalance the action of the fluid in the first chamber 18a against the actuator 22.

The first chamber 18a is fluidly connected through the duct 21, as stated, to the valve 17 and, by means of a duct 24, to an outlet 25; the second chamber 18b is fluidly connected to the second valve 19 by means of a delivery duct 27 and a return duct 29.

The second valve 19 may be an electrically actuated two-position three-way valve, configured to assume two positions, a first position in which the fluid can flow from the conduit 27 coming from the intensifier 18 to the pilot valve 11 through a conduit 33 and a second position in which the fluid can flow from the duct 33 towards the second chamber 18b through a duct 29. Advantageously, the electrical actuation of the valve 19 is given by a signal received from the change in position of the valve 17; in particular, when the valve 17 is positioned so that the fluid from the source P does not flow into the intensifier 18, then the valve 19 is positioned so that the fluid can flow from the duct 33 towards the chamber 18b, on the contrary, when the valve 17 is positioned so that the fluid from the source P flows into the intensifier 18, then the valve 19 is positioned so that the fluid flows from the intensifier 33 to the pilot valve 11 through a conduit 33.

The operation of the second embodiment described above is as follows.

In a first operating mode of the HITBV 5 (Figure 2A), in which the first module 6 is engaged, the valve 12 is closed and the valve 17 is positioned so as to allow fluid communication between the source P of pressurized fluid and the intensifier 18; consequently to this position of the valve 17, the valve 19 is positioned so that the fluid from the intensifier 18 can flow into the pilot valve 11. In this configuration the fluid coming from the source P passes through the valve 17 and flows into the chambers 18a and 18b of the intensifier 18 and, in parallel, pushes the actuator 22 against the spring 23 thus increasing the pressure of the fluid passed into the chamber 18b which is pushed, through the duct 27 and the valve 19, into the pilot valve 11. Then, according to the value of the fluid pressure deriving from the pressure P, a corresponding pressure value is imparted on the valve 3 of the trailer brake in area A, limited by the maximum pressure Pmax and by the second line C, despite the pressure signal received from the main cylinders 2.

According to the above, the HITBV 5 guarantees the hydraulic control of the pressure imparted to the brake valve 3 in area A limited by the maximum pressure Pmax and by the second line C.

In a second mode of operation of the HITBV 5, in which the first module 6 is not engaged, the valve 12 is engaged and the operation of this embodiment is the same as the first embodiment.

In parallel to the operating modes described above, the third module 8, through the valve 16, detects whether the pressure signal received by the main cylinders 2 is greater than Pcyl_adm and acts as described for the first embodiment.

According to a third embodiment of the present invention, particularly dedicated to the vehicle which uses the same oil for the transmission and for the brake circuits at a pressure up to about 20-25 bar and shown in figure 3, the first module 6 comprises only a valve 17, fluidly interposed between a source P of pressurized fluid and the pilot valve 11.

In greater detail, the valve 17 may be an electrically actuated two-position three-way proportional valve configured to assume two positions, a first position in which the fluid can flow from the source P to a pilot valve 11 through a conduit 21 and a second position in which the fluid can flow from the duct 21 into the drain D.

The operation of the third embodiment described above is as follows.

In a first operating mode of the HITBV 5 (Figure 2A), in which the first module 6 is engaged, the valve 12 is closed and the valve 17 is positioned so as to allow fluid communication between the source P of pressurized fluid and the pilot valve 11. Then, according to the value of the fluid pressure deriving from the pressure P, a corresponding pressure value is imparted to the valve 3 of the trailer brake in the area A, limited by the maximum pressure Pmax and by the second line C, despite the pressure signal received from the main cylinders 2.

According to the above, the HITBV 5 guarantees the hydraulic control of the pressure imparted to the brake valve 3 in area A limited by the maximum pressure Pmax and by the second line C.

In a second mode of operation of the HITBV 5, in which the first module 6 is not engaged, the valve 12 is engaged and the operation of this embodiment is the same as the first embodiment.

In parallel to the operating modes described above, the third module 8, through the valve 16, detects whether the pressure signal received by the main cylinders 2 is greater than Pcyl_adm and acts as described for the first embodiment.

Considering the foregoing, the advantages of an intelligent trailer brake valve 5 according to the invention are evident.

First of all, this HITBV 5 is hydraulic and therefore can be applied to vehicles equipped only with hydraulic systems and does not require the installation of a dedicated pneumatic circuit.

Thanks to its hydraulic typology, the HITBV 5 guarantees the control of the trailer brake valve 3 as known for pneumatic valves, thus allowing a control of the trailer brake valve 3 independently of the pressure signal received from the main cylinders 2, avoiding thus the “Jack-Knife” phenomenon between tractor and trailer in the tractor-trailer system.

Furthermore, the presence of the second module 7 ensures braking, even if along a standard proportional characteristic along line C, by the trailer brake valve 3 if the first module is not engaged.

It is clear that modifications can be made to the intelligent trailer brake valve 5 described that do not extend beyond the scope of protection defined by the claims.

For example, the valves 12, 17 and 19 or the intensifier 18 or the valves 4 and 11 can be replaced by equivalent means.

Claims (1)

CLAIMS 1.- Intelligent hydraulic trailer brake valve, HITBV, (5) configured to be fluidly interposed between the braking actuation means (2) and a trailer brake valve (3) of a work vehicle, called HITBV (5 ) including: ● a first module (6) fluidly interposed between a source (P) of pressurized fluid of said work vehicle and said trailer brake valve (3), said first module (6) being configured to control said valve (3) of the brake independently of the pressure signal imparted by said braking actuation means (2) to said HITBV (5); ● a second module (7) fluidly interposed between said braking actuation means (2) and said trailer brake valve (3), said second module (7) being configured to control said brake valve (3) directly proportional to a pressure signal received by said braking actuation means (2) when said first module (6) is not engaged; And ● a third module (8) fluidly interposed between said braking actuation means (2) and said trailer brake valve (3), said third module (8) being configured to control braking, when the pressure signal imparted by the braking actuation means (2) for said HITBV (5) is greater than a preset threshold (Pcyl_adm). 2.- Hydraulic HITBV according to claim 1, wherein said second module (7) comprises a valve (12) controlled to allow or deny the passage of said pressure signal towards said brake valve (3). 3.- Hydraulic HITBV according to claim 2, wherein said valve (12) is an electrically actuated ON-OFF valve. 4.- Hydraulic HITBV according to any one of claims 1 or 2, wherein said third module is fluidly in parallel with said second module (7). 5.- Hydraulic HITBV according to any one of claims 1 to 3, wherein said third module (8) comprises valve means configured to receive in input a pressure signal from said braking actuation means (2) and to supply as output a pressure signal according to a preset characteristic when said pressure signal is greater than a preset threshold (Pcyl_adm). 6.- A hydraulic HITBV according to claim 5, wherein said valve means comprise a counterbalance valve (16). 7.- Hydraulic HITBV according to any one of claims 1 to 6, wherein said first module (6) comprises a first valve (17), an intensifier (18) and a second valve (19) fluidly connected in series, said first valve (17) being configured to allow the passage of a first fluid from said source (P) to said intensifier (18), the latter comprising a first chamber (18a) in which said first fluid flows and a second chamber (18b) configured to house a second fluid, said intensifier (18) being configured to increase the pressure of said second fluid based on the pressure of said first fluid, said second valve (19) being configured to allow the passage of said second fluid from said intensifier (18) to said brake valve (3). 8.- Hydraulic HITBV according to any one of claims 1 to 6, wherein said first module (6) comprises a first valve (17), an intensifier (18) and a second valve (19) fluidly connected in series, said first valve (17) being configured to allow the passage of a fluid from said source (P) to said intensifier (18), the latter being configured to increase the pressure of said fluid between a first chamber (18a) and a second chamber ( 18b) of said intensifier (18), said second valve (19) being configured to allow the passage of said second fluid from said intensifier (18) to said brake valve (3). 9.- Hydraulic HITBV according to any one of claims 1 to 6, wherein said first module (6) comprises a valve (17), said valve (17) being configured to allow the passage of a fluid from said source (P) to said brake valve (3). 10.- Hydraulic HITBV according to any one of claims 7 to 9, wherein said valve (17) is an electrically actuated two-position three-way proportional valve. 11.- Hydraulic HITBV according to any one of claims 7 or 8, wherein said second valve (19) is an electrically actuated two-position three-way valve. 12.- Hydraulic HITBV according to any one of claims 7 or 8, wherein said second valve (19) is controlled on the basis of the position of said first valve (17). 13. A hydraulic HITBV according to claim 7, wherein said first fluid is a transmission fluid and said second fluid is a brake oil. 14.- Hydraulic HITBV according to claims 8 or 9, wherein said fluid is a brake oil. 15.- Hydraulic HITBV according to any one of claims 1 to 14, wherein said first module (6), said second module (7) and said third module (8) are fluidly connected together, upstream of said valve (3) of the brake, to a valve (11) configured to allow the passage of fluid at a higher pressure.