WO1995017328A1

WO1995017328A1 - Arrangement for influencing the joint angle between sections of an articulated vehicle

Info

Publication number: WO1995017328A1
Application number: PCT/HU1994/000062
Authority: WO
Inventors: László CSORDÁS; Valér MERZA; József RÖHBERG; Gyula Tóth
Original assignee: Autóipari Kutató És Fejleszto^' Rt
Priority date: 1993-12-23
Filing date: 1994-12-21
Publication date: 1995-06-29
Also published as: HUT69546A; HU213562B

Abstract

The invention relates to the hinged coupling connecting the sections of an articulated motor vehicle, mainly of an articulated bus, for influencing the jack-knifing movement of said sections to prevent development of excessively high angular speeds of jack-knifing. On the vehicle, one or two hydraulic working cylinders are arranged, the piston rods of which are coupled to one section while the cylinders are connected to the other section, each working cylinder being linked up with a fluid-replenishing and equalizing reservoir, expediently, with a common pressurized hydropneumatic unit, with a check valve and a pressure limiting valve being arranged parallel with the check valve in each of said connecting lines, having further connecting lines (16a, 30a, 36a and 16b, 30b, 36b) coupled to the working chambers (10a and 10b) of the cylinders, said connecting lines being branched off a common line (18), in the connecting lines (36a, 36b) of each working cylinder (6a, 6b) a check valve (37a, 37b) closed toward said branched-off common line (18), is accommodated, in the lines (30a, 32a, 35a and 30b, 32b, 35b), between each of said check valves (37a, 37b) and working spaces (10a and 11a) of the working cylinders (6a and 6b) parallel chokes (31a, 33a, 34a and 31b, 33b, 34b) are connected into peripheral groove (27a and 27b) of a rotary valve (24) provided with control edges (29a and 29b) and always being in an angular position proportional to the momentary joint angle (β) of the vehicle (1).

Description

ARRANGEMENT FOR INFLUENCING THE JOINT ANGLE BETWEEN SECTIONS OF AN ARTICULATED VEHICLE

TECHNICAL FIELD

The invention relates to the hinged coupling connecting the sections of an articulated motor vehicle, mainly of an articulated bus, for influencing the jack-knifing movement of said sections to prevent development of excessively high angular speeds of jack-knifing, be this displacement directed inward (e.g. during braking or acceleration) or outward (e.g. when turning, under the effect of centrifugal force).

BACKGROUND ART

There are known mechanisms proposed and realized for solving the above task. In mechanisms successfully accomplishing said aim, the force preventing excessive jack-knifing is caused by hydraulic means controlled by an electronic setup after evaluating the relation of the steering angle to the joint angle. The solution is technically exacting, requiring continuously self-checking during travel to be included in the electronic unit, since improper operation may lead to serious mass accidents. Therefore, such arrangements are used in cases where these are absolutely indispensable, such as in push-type articulated buses, where an axle of the trailer section is driven. With buses, beside their anti-blocking feature, the anti- jack-knifing device thereof represents the first item to be equipped with electronic control, said device having an important role in ensuring safe participation of such vehicles in road traffic, since any malfunctioning of their anti-jack-knifing device may be the immediate cause of an accident. The decisive majority of users are unprepared to perform the checking and maintenance of such devices required ensuring their proper operation. Just therefore, proposals have emerged relating to anti-jack-knifing devices where the use of electronics has deliberately been dispensed with. No such arrangements have been appeared in practice so far, presumably because the efforts toward simplification went to the detriment of accomplishing the aim itself. An electronically controlled setup most widely used in practice is described in Patent Specification DE-2.420.203. Less often adopted devices are proposed in Patent Specifications DE-3.330.387 and HU-191.474. Conversely, a proposal covered by Patent Specification HU-182.445 has failed to prove suitable for practical use because the detection of the steering angle and the hydraulic transmission of angle signals have not been found sufficiently sensitive and practicable, due to the long transmission path of signals between the hinge assembly and the steered axle.

In devices having found practical acceptance - following the introduction of the first anti-jack-knifing mechanism proposed in Patent Specification DE-2.420.203 - the application of large-size working cylinders has become general, where the cylinders are coupled to one of the vehicle sections, with the piston rods, by pairs, being attached to the other vehicle section. The object of our invention is also of that type and of similar arrangement. Such assemblies are known as applied to articulated vehicles, where the two vehicle sections are linked either through a spherical joint or through a rotary gear rim. The latter type of linkage is described in Patent Specification DE-4.007.684 and in a patent report published under number HU-730/91. In the arrangement described in the latter publications the working chambers of the double-acting hydraulic working cylinders are connected through check valves and from a point lying between said valves a line is branching off, into which a pressure limiting valve is installed to make up for the clearance losses and to equalize the difference between piston displacements. A hydraulic loop is led to each working space, said loop comprising a choke pertaining to the respective working, each connected in series with a check valve, the two valves being arranged to shut off the opposite direction of flow.

These chokes are adjustable. With these fittings the damping resistance is determined not only by the throttling resistance of these chokes, but also by the asymmetrical arrangement of the pistons with respect to the axis of jack-knifing and by the connection of both pistons to the same peripheral point of the rotary ball rim: Thereby, the torque acting against jack-knifing is jointly determined by the direction of force - i.e. by direction of the center lines of working cylinders - and the magnitude of the force caused by the throttling effect. DISCLOSURE OF INVENTION

The aim of our invention has been to create a device to influence the articulation angle and to produce an anti-jack-knifing effect, by means of which - without resorting to electronic position evaluation and control, at the most by electric control through hydraulic means - satisfactory force/torque conditions can be obtained by using an assembly equally suitable for being used in articulated vehicles, mainly in buses, having sections coupled to each either through a spherical joint, or through a rotary gear rim.

Our aim has been achieved by an arrangement exerting a step- wise progressively increasing resistance against the increasing joint angle, independently of the steering angle, the size of said increasing resistance being dependent on other run- dynamic parameters, e.g., on vehicle speed, air pressure in airbrake of vehicles or other factors. At the same time, against a decreasing joint angle the device exerts unvarying feeble resistance.

Object of our invention is a device for influencing the relative movement of the front section with respect to the trailer section of an articulated motor vehicle, mainly of a bus, where, arranged on the vehicle, one or two hydraulic working cylinders are arranged, the piston rod or rods of that working cylinders are coupled to one section e.g. to the front section of the vehicle, while the cylinder or cylinders of the one or two working cylinders are connected to the other section e.g. to the trailer section of the vehicles, each working cylinder being linked up, through connecting lines, with a fluid-replenishing and equalizing reservoir, expediently, with a common pressurized hydropneumatic unit, with a check valve and a pressure limiting valve being arranged parallel with the check valve in each of said connecting lines.

According to our invention, the device has further connecting lines coupled to the working chambers of the cylinders, said connecting lines being branched off a common line, in the connecting lines of each working cylinder a check valve closed toward said branched-off common line, is accommodated, in the lines, between each of said check valves and working spaces of the working cylinders parallel chokes are connected into peripheral groove of a rotary valve provided with control edges and always being in an angular position proportional to the momentary joint angle of the vehicle, said chokes being shut off in successive angular positions, where in the branched-off common line an electrically actuated two-position solenoid valve is installed, in the first position of which and to its first outlet, through a hydraulic line directly, and in the second position of which and to its second outlet, through a series choke and line, the hydraulic reservoir is attached, while the solenoid of the two-position valve is connected to the control/evaluating unit issuing first and second output signal, said unit having at least one sensing unit detecting actual run-parameter of the motor vehicle.

In a suitable embodiment of our invention the working cylinders are of the double- action type, with their working chambers cross-connected, and at least three chokes are connected through separate lines to each periperal groove of the rotary valve.

In a further suitable embodiment of our invention the sensed run-dynamic characteristics comprise the travelling speed and the air-brake pressure, where the first output signal in the control/evaluating unit is ordered to p < 2 bar air-brake pressure and to v < 40 km/h vehicle speed, whereas the second output signal is ordered either to p < 2 bar air-brake pressure or to v > 40 km/h vehicle speed, or to both.

BRIEF DESCRIPTION OF DRAWINGS

The invention is described in detail in the following paragraphs, referring to the attached figure 1 showing an example of the embodiment, in which the region of articulation of the vehicle and the arrangement of the device influencing jack-knifing is illustrated.

BEST MODE FOR CARRYING OUT THE INVENTION

The front section 2 of an articulated vehicle 1 and a trailer section 3 is coupled through a hinge 4 provided with a joint device for influencing the angle of articulation. Axially symmetrical with respect to hinge 4 hydraulic working cylinders 6a and 6b are mounted between the front section 2 and trailer section 3, said cylinders being attached through hinges 12a and 12b to the trailer section 3, and with their cylinders 9a and 9b and with their piston rods 7a and 7b through hinges 13a and 13b to the front section 2. The hydraulic working cylinders 6a, 6b are double-acting units, with their piston rods 7a, 7b separating working chambers 10a and 11a, 10b and l ib, respectively. The working chamber 10a is permanently connected through hydraulic line 14a with the working chamber l ib of working cylinder 6b, further the working chamber 11a - above the piston rod 7a - of the working cylinder 6a is permanently connected through hydraulic line 14b with the working chamber 1 Ob - under the piston rod 7b - of the working cylinder 6b.

The working chambers 10a and 10b are connected with interposed lines 14a and 14b through hydraulic lines 15a and 15b, respectively, to the left-hand side inlet 55a and right-hand side inlet 55b of the valve unit 22 (when looking at the top view in the direction of travel), to the common outlet 61 of which, through hydraulic line 23, a reservoir 21 is attached, in which hydraulic fluid 62 is stored to replenish the hydraulic fluid displaced by pifcton rods 7a and 7b, and to make up for the leakage losses. At the surface 63 of the hydraulic fluid 62 a swimmer 64 is provided to actuate an electric switch 65 serving for controlling, through electric leads 66, a pilot lamp 67 located in the not-shown facia board of the articulated vehicle 1 to inform the driver. The air space 71 of reservoir 21 is connected through a check valve 70 and a line 68 to a compressed-air supply 69 to keep the hydraulic system under constant pressure.

To the hydraulic lines 15a and 15b, through lines 16a and 16b, a hydraulic choke 17 is installed, to which - through a hydraulic line 18 - an electro-hydraulic valve assembly 19 is connected. To an input 45 of a solenoid 44 of the two-position valve 39 of said electro-hydraulic valve assembly 19, an electric/electronic control/evaluating unit 47 is by means of line 46 connected, said unit 47 being provided with at least one sensing unit 49, connected to it by lead 48. To the electro-hydraulic valve assembly 19 a pilot lamp 54 is connected through electric lead 53 to indicate the valve position.

The arrangement of units mentioned above isdescribed here below: The choke valve unit 17 comprises a rotary valve 24, with a rotary slide valve 26 accommodated in the valve body 25, the angular displacement of said valve 24 being equal to the joint angle β indicated by arrow (-β- +β) (the mechanism causing the displacement is not shown in the drawing). In the rotary slide valve 26 channels 28a and 28b are provided, these being connected, in turn, with lines 16a and 16b. Channel 28a terminates in peripheral groove 27a, channel 28b terminates in peripheral groove 27b, and the central angle pertaining to their arc length is equal to, or exceeding, the maximum joint angle β toward either side, i.e. β = approx. 90°, with control edges 29a and 29b on their ends.

According to the embodiment shown as an example, each of the peripheral grooves 27a and 27b provided in the valve body 25 is coupled with three connecting lines 30a, 32a, 35a and with lines 30b, 32b, 35b, respectively, in the middle (rest) position of rotary slide valve 26. The rotary slide valve 26 in its said middle position rests at the joint angle of articulation β = 0°, and its angular displacement is always equal to the joint angle β . In that middle position, the connection point of line 30a is near the end of periperal groove 27a, that of line 35a lies at the bisector of the arc length of said periperal groove 27a, and that of line 35a lies at a point located in the bisector of the arc length falling between the connection points of the mentioned two lines 30a and 35a. Thus, the connection points of the outer two lines 30a and 35a assuming outside positions with respect to line 32a and connected on either side of the middle line 32a lie along the arc length of periperal groove 27a, in positions displaced by a central angle of 45° apart from each other. On the other side, the arrangement of peripheral groove 27b and lines 30b, 32b and 35b is similar, i.e. symmetrical with respect to the diameter, when viewed in the cross- sectional plane of the rotary slide valve 26. In line 30a a choke 31a, in line 32a a choke 33a and in line 35a a choke 34a is installed and, similarly, in line 30b a choke 31b, in line 32b a choke 33b and in line 35b a choke 34b is installed, all chokes being replaceable and of adjustable design.

The other ends of lines 30a, 32a and 35a connected to form a common line are led to a check valve 37a closed toward said lines and similarly in the common line 37b of connected lines 30b, 31b and 35b a check valve 37b is installed, closed in direction of the respective lines. To the common end 38 of lines 36a and 36b, through line 18, the next electro-hydraulic valve assembly 19 is connected. This assembly is provided with a solenoid-operated two-position valve 39, to the input 40 of which the line 18, to its first outlet 42 the line 51 , to its second outlet 43 a choke 50 is connected. Said line 51 and said choke 50 are linked up with line 20, which in turn is connected into reservoir 21. In the first position of solenoid- operated two-position valve 39 the first outlet 42 is open, the second outlet 43 is closed, in its second position the open/closed positions are reversed. The solenoid- operated two-position valve 39 is provided with a hydraulic meter connection 41 and an electric control switch 52. To the switched-off position of said switch 52 the open position of the first outlet 42 and to its switched-on position the open position of the second outlet 43 is ordered.

The next unit to be described is the valve unit 22. To the left-hand side inlet 55a of said valve unit 22 a hydraulic line 15a, to its right hand side inlet 55b a hydraulic line 15b is connected. To inlet 55a the line 56a of valve unit 22 is attached, said line being fitted with a check valve 57b closed in the direction of inlet 55b. Parallel with check valves 57a and 57b, the pressure limiting valves 59a and 59b are arranged into the respective by-pass lines 58a and 58b. To the connection point 60 of lines 56a and 56b the line 23 is connected, said line 23 forming at the same time, the outlet 61 of valve unit 22.

The equipment operates in the following way:

Figure 1 illustrates the top view of the articulated vehicle 1, so, in left turn, the piston rod 7a of working cylinder 6a is displaced in the direction of compression, in right turn said piston rod 7a is displaced in the direction of extension, in straight travel - by joint angle β = 0° - the piston rod is in middle position. The piston rod 7b of working cylinder 6b always moves in the direction opposed to that of piston rod 7a.

The front section 2 of the articulated vehicle performs larger or smaller angular displacements swinging with respect to the trailer section 3 and to hinge 4, even if not induced by steering. These swings are damped by joint device 5. When trailer section 3 swings to the left from the β = 0° position, then hydraulic fluid flows from the working chamber 10a of working cylinder 6a and from the working chamber 10b of working cylinder l ib through line 14a, across lines 15a, 16a, through channel 28a into the peripheral groove 27a, from where it passes simultaneously through all the three connecting lines, i.e. through line 30a and choke 31a, through line 32a and choke 33a, and through line 35a and choke 34a, across a cross-sectional area of flow now being the largest. The hydraulic fluid passes further, opens the check valve 37a, and at junction point 38 it flows into line , 18. In the direction of check valve 37b no flow takes place in line 36b, since the flow in that direction is blocked by said check valve 37b.

From common line 18 the hydraulic fluid flows into the solenoid-actuated two- position valve 39. When the articulated vehicle 1 travels at a speed below 40 km/h, without simultaneous braking, the first outlet 42 being connected with inlet 40 of the solenoid-operated two-powition valve 39, the hydraulic fluid flows into reservoir 21.

When the articulated vehicle 1 travels at a the brake being operated, then in the two-position solenoid valve 39 the inlet 40 is connected with second outlet 43, from where the hydraulic fluid flows through choke 50 and line 20 into reservoir 21. Said two-position solenoid-valve 39 is switched over into this position by the electric control/evaluating unit, when solenoid 44 is energized. This operation is carried out when a travelling speed exceeding 40 km/h is sensed by the sensing unit 49, and/or when the pressure in the brake actuating elements of the brake system exceeds the level of two bars.

The damping force arising in the working cylinders 6a and 6b and the damping torque around hinge 4, respectively, are basically determined by the resistance of chokes 31a, 33a, 34a and 50.

Beyond a joint angle of maximum β ^*= 6° the swinging-out trailer section starts to move in reverse direction, the angle decreases, while the hydraulic fluid starts to flow from reservoir 21 back into the expanding working chambers 10a and l ib.

When this reverse swinging movement reaches the β = 0° position and moves into the other direction, then the process takes place in an analoguous way with the right-hand side elements - identified by "b" - of the system.

When, under the effect of steering, the vehicle 1 starts to make a turn, and the joint angle deviates from β = 0°, then the valve body 25 is angularly displaced with respect to the rotary slide valve 26 rigidly attached to the front section 2 of the articulated vehicle 1 , so that the angular displacement is always identical with the joint angle β when the joint angle exceeds the value of β = 6° then - in a left turn - line 30a, and thereby also the choke 31a, is shut off by the control edge 29a of the rotary slide valve 26. Consequently, the fluid displaced from working chambers 10a and l ib and passing through lines 14a and 15a, through channel 28a and through peripheral groove 27a, is forced to flow through chokes 33a and 34a. Thus, the overall cross-sectional area of flow is determined by the two chokes 33a and 34a, this cross-sectional area being smaller than the sum of the three parallel connections. The flow route of the hydraulic fluid leaving the chokes 33a and 34a through line 36a is the same as that given in the description of damping.

Thus, the force arising in the working cylinders 6a and 6b, acting against the angular displacement of trailer section 3, and the resistive torque around hinge 4 are increased stepwise. When the joint angle β approaches the value β = 25°, then by the control edge of rotary slide valve 29a, the line 32a and thereby also the choke 33a, is shut off, so that the fluid has to pass exclusively through choke 34a. The available cross- sectional area of flow is given by that of the only open choke 34a, this area being smaller than the sum of the three parallel connections. The flow route of the hydraulic fluid leaving the choke is the same as that given further above in the description of damping.

Thus, the force arising in the working cylinders 6a and 6b and acting against the angular displacement of trailer section 3, and respectively, the resistive torque around hinge 4 are increased in steps.

In the next step of increase of resistance on reaching the maximum value of the joint angle β, in left turn, the line 35a is shut off by the control edge 29a of rotary slide valve 26, all the three lines, 30a, 32a and 35a get closed, whereby the device becomes blocked against any further increase of the joint angle β. In the direction of reducing joint angles β, i.e. when the articulated vehicle gradually straightens while coming out of a turn, no considerable resistance is exerted by the hydraulic system. The route of flow of the fluid into the expanding working chambers 10a, and l ib from the reservoir 21 has already been described further above.

INDUSTRIAL APPLICABILITY

The force arising in the working cylinders and acting against the angular displacement of the trailer section, and respectively, the resistive torque around the hinge are increased in steps, influencing the jack-knifing movement of the sections of the articulated vehicle preventing development of excessively high angular speeds of jack-knifing, be this displacement directed inward (e.g. during braking or acceleration) or outward (e.g. when turning, under the effect of centrifugal force).

Claims

1. Device for influencing the relative movement of the front section with respect to the trailer section of an articulated motor vehicle, mainly of a bus, where, arranged on the vehicle one or two hydraulic working cylinders are arranged, the piston rod or rods of which working cylinder or cylinders are coupled to one section e.g. to the front section of the vehicle, while the cylinder or cylinders of the one or two working cylinders are connected to the other section e.g. to the trailer section of the vehicles, each working cylinder being linked up, through connecting lines, with a fluid-replenishing and equalizing reservoir, expediently, with a common pressurized hydropneumatic unit, with a check valve and a pressure limiting valve being arranged parallel with the check valve in each of said connecting lines characterized in having further connecting lines (16a, 30a, 36a, and 16b, 30b, 36b respectively) coupled to the working chambers (10a and 10b, respectively) of the cylinders, said connecting lines being branched off a common line (18), in the connecting lines (36a, 36b, respectively) of each working cylinder (6a,6b) a check valve (37a, 37b, respectively) closed toward said branched-off common line (18), is accommodated, in the lines (30a, 32a, 35a and 30b, 32b, 35b), between each of said check valves (37a, 37b, respectively) and working spaces (10a and 11a respectively) of the working cylinders (6a, and 6b, respectively) parallel chokes (31a, 33a, 34a, and 31b, 33b, 34b) are connected into peripheral groove (27a and 27b, respectively) of a rotary valve (24) provided with control edges (29a and 29b, respectively) and always being in an angular position proportional to the momentary joint angle (β) of the vehicle (1), said chokes being shut off in successive angular positions, where in the branched-off common line (18) an electrically actuated two-position solenoid valve (39) is installed, in the first position of which and to its first outlet (42), through a hydraulic line (51, 20, respectively) directly, and in the second position of which and to its second outlet (43), through a series choke (50) and line (20), the hydraulic reservoir (21) is attached, while the solenoid (44) of the two-position valve (38) is connected to the control/evaluating unit (47) issuing first and second output signal, said unit (47) having at least one sensing unit (49) detecting actual run-parameter of the motor vehicle (1).

2. Device as claimed in Claim 1 characterized in ordering the first output signal in the control/evaluating unit (47) to air brake pressure p < 2 bar and to vehicle speed v < 40 km/h, and by ordering the second output signal to p > 2 bar air brake pressure or to vehicle speed v < 40 km/h, or to the latter two values detected as run-dynamic parameters by the sensing unit (49).

3. Device as claimed in Claim 1, characterized in having double-acting working cylinders (6a, 6b), with their working chambers (10a, 10b and 11a, lib) respectively, being cross-connected by hydraulic lines (14a, 14b).

4. Device as claimed in Claim 1, characterized by having at least three parallel chokes (31a, 33a, 34a and 31b, 33b, 34b) connected to each peripheral groove through lines (30a, 32a, 35a and 30b, 32b, 35b, respectively).