DE1115598B - Hydraulic system for motor vehicles, especially tugs - Google Patents

Description

The invention extends to a hydraulic system for motor vehicles, in particular tractors, according to patent 1022 917. According to claim 1 of the main patent, with hydraulic systems a pressure pump driven by the vehicle engine and at least one at a high pressure sized working device in the form of a working cylinder and / or liquid motor the arrangement of a pressure relief valve in the return line for the pressure fluid from the working devices to the oil sump created the possibility of with the same pressure pump that is used to generate the high that is only temporarily required Pressure is used to operate the work devices, even during the entire operating time of the motor vehicle required comparatively low overpressure in the interior of a known per se connected to the hydraulic system continuously variable fluid transmission to maintain. According to the invention, the teaching of Main patent also known on both agricultural and other vehicles hydraulic systems extended, in which one or more of the high pressure working cylinder as Brake cylinders of the vehicle brake system are formed and a control member is provided through which the Working pressure in the brake cylinders can be regulated. This will be done with a hydraulic system Vehicles equipped according to the main patent, especially tractors, with a particularly simple one and fully sufficient auxiliary power brake for any vehicle or trailer weight equipped without the construction costs noticeably compared to the previously used mechanical brakes raise.

In the simplest embodiment, the pressure medium delivered by the motor-driven pump can even via the control member, which is preferably to be actuated by a pedal, or its several - z. B. separately for the left and right drive wheel - fed directly to the brake cylinders in the wheel brakes will. In this case, either the return springs for the brake shoes must be dimensioned as strong in a known manner be that after switching the control member from the high actuation pressure to the constant slight overpressure in the pressure medium system to release the pressure medium against this overpressure of the brakes out of the brake cylinders again, or it must be used for the return of the pressure medium a separate one from the brake cylinder or cylinders from the control member to the collecting container unpressurized return line must be laid.

Hydraulic system for motor vehicles,
especially tugs

Addendum to patent 1,022,917

Applicant:

Allgaier-Werke G. mb H.,
ίο Uhingen (Württ.)

Dipl.-Ing. Kaspar Ritter, Kirchheim (Teck),

and Dipl.-Ing. Wolfgang Hütter,.
Göppingen-Bezgenriet,

have been named as inventors

An advantageous embodiment of the hydraulic system according to the invention now consists in that the brake system in a known manner consists of at least one master cylinder and several wheel brake cylinders has a separate fluid system with the associated pipelines, wherein the piston in the master cylinder and the piston can be acted upon by the motor-driven pressure pump Working cylinders are mechanically coupled by a linkage. That way you can in the two hydraulic systems different special requirements for lubricity, Cold resistance, etc. adapted pressure medium can be used.

The working cylinder, which can be acted upon by the motor-driven pressure pump, is advantageously in this way designed that the piston in the can be acted upon by the pressure pump working cylinder for the Brake actuation in a manner known per se with its rear side to one likewise with the pressure medium The filled space is bordered by the return line which is constantly under slight overpressure connected is. This measure ensures that the pressure and the flow rate in the return line remain constant even during the brake application, which is important for the operation of the connected continuously variable transmission is desired. At the same time, the use of a of such a working cylinder with the rear of the piston connected to the return line, the need to reinforce the return springs for the brake shoes.

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However, the difference between the piston areas on the front and back of the piston remaining differential force and the piston friction in the brake cylinders when the brakes are released, if possible to overcome quickly, it is within the scope of the invention, the piston or the mechanical linkage to be brought into operative connection with a separate return spring.

To the brake connected to the hydraulic system in its effect by each - intended or accidental — simultaneous switch-on To make another working device independent, it is also particularly advantageous that First switch on the control element for the brake actuation in the pressure line coming from the pressure pump and to train in a known manner so that by pressing the brake to the control member for further high-pressure work devices leading pressure line automatically shut off will. It is therefore advisable to turn on the control member for brake actuation in a known manner the pressure generated by the pump in the pressure line limiting ■ pressure relief valve parallel to switch to avoid overloading of the pump and its drive during the brake actuation times to prevent, in which only a relatively small amount of the pressure medium is needed, but the drain to the normal return line is blocked at the same time.

A particularly fine regulation of the braking effect can be achieved with the hydraulic system according to the invention System finally achieve that in a known manner the control member for the Brake actuation a pressure relief valve is connected in parallel, the one depending on the position the brake pedal has variable contact pressure. This allows one to follow the path of the Achieve a proportional increase in pressure in the brake line and the brake cylinders using the brake pedal.

The following are three exemplary embodiments of the invention on the basis of the drawing with five illustrations explained in more detail. Of these shows in detail

Fig. 1 shows a hydraulic system according to the invention with directly connected brake cylinders in Circuit diagram,

Fig. 2 and 3 the control element for the brake only in the release and braking position,

Fig. 4 shows the different part of a slightly modified hydraulic system with a separate one Pressure medium system for the brake in turn in the circuit diagram and

Fig. 5 a modified control element for the brake actuation in connection with a pressure relief valve, its response pressure can be changed automatically depending on the brake pedal position is, in longitudinal section.

Using the same reference numerals for the same parts as in the description of the Main patent denotes 1 in Fig. 1 a z. B. via a pinion 2 from not shown Tractor motor-driven pressure pump, which through a suction line 3 the liquid pressure medium from a Sump 4 sucks in and promotes into a pressure line 5. In the pressure line 5 with the extension 5 'is again a control slide 6 is arranged, by pivoting it out of the position shown in FIGS Neutral position counterclockwise the pressure medium either a working cylinder? or a hydraulic fluid motor 8 can be supplied. In the case of the In the neutral position of the control slide 6, the pressure medium flows through the channel 9 of the slide 6 and the return line 10 into the sump 4 back. Through the into the return line 10 or the feed line 13 Overpressure valves 11 or 12, which are switched on for working cylinder 7, are in return line 10

ίο constantly a little, due to the bias of the Maintain valve springs controllable overpressure, which is known for the operation of a Branch line 14 connected to the hydraulic system, continuously variable fluid transmission 15 is required for the vehicle drive in the interior of the transmission. The piston 18 in Working cylinder 7 expediently borders with its rear side on a likewise closed and during of the operation with the pressure medium-filled space 19, which is constantly connected to the through a line 20 Return line 10 is in communication, so that even during the filling times of the cylinder 7 with under high pressure liquid the pressure and the flow rate in the return line 10 through the pressure medium displaced from the space 19 by the piston 18 is kept constant.

According to the present invention, there is still another - preferably - in the pressure line 5 Control member 24 is switched on, which can be operated by a pedal 21 via a linkage 22, 23. This control element 24 connects when adjusting from the rest position shown in Figs. 1, 2 and 4 with the open Passage for the pressure medium through the line 5 'to the control slide 6 in the one shown in Fig. 3 Activate the pressure line 5 with a pressure line serving to actuate the vehicle brake 25 and at the same time blocks the part 5 'of the pressure line 5 leading to the control slide 6. In the exemplary embodiment according to FIG. 1, the brake cylinders 26 and 27 of the tractor brakes 28 and 29 and the brake cylinders 30 and 31 of the trailer brakes 32 and 33, the latter by a releasable coupling 34 are connected to the pressure line 25 when the control member 24 is actuated with the aid of the pedal 21 in the direction of the arrow 25 through the pressure medium conveyed by the pressure pump 1 applied directly and thereby the brake shoes against the brake drums not shown pressed. After the pedal 21 is released, it is activated together with the control member 24 the return spring 36 is pivoted again counter to the direction of arrow 35 into the rest position according to FIGS. 1, 2 and 4 and thereby the return line 37, 37 'opened through the slot 38, so that the correspondingly strong sized return springs 39 to 42 the brake shoes while displacing the pressure medium from the Brake cylinders 26, 27 and 30, 31 against the remaining, determined by the valve 11 low Raise the overpressure in the return line 10 again.

Instead of the one shown in Figs. 1 to 4, a control member 24 for the brake actuation can also two - optionally individually or jointly operable - control members are used, of which each influences the pressure medium inlet and outlet for the brake cylinder of a drive wheel brake and thereby using the brakes as a steering aid for turning with the smallest radii in a manner known per se allowed.

The exemplary embodiment according to FIG. 4 differs from that described with reference to FIGS. 1 to 3 especially in that the when pivoting the lever 23 in the direction of arrow 35 by the Control element 24, line 25 connected to pressure line 5, to a high-pressure working cylinder 43 leads, the piston 44 of which with the piston 45 of a brake master cylinder 46 is one of the usual Parts such as brake oil reservoir 47, wheel brake cylinders 26, 27 and the associated connecting lines and possibly a coupling 34 to a trailer brake existing hydraulic brake system with a separate hydraulic fluid system is mechanically connected by a linkage 47, 48. The return line 37 for the pressure medium from the working cylinder

43 is only connected to the further return line 37 'through the slot 38 when the control member 24 is in the rest position, but is closed by the control member 24 _{during the actuation of the brake - just like the further ao pressure line 5'.} In contrast, the space 49 adjoining the rear of the piston 44 is constantly connected to the return line 37 ', so that the slight overpressure determined by the pressure relief valve 11 in the return line 10 always prevails in the space 49. By acting on the connecting rod 47, 48 of the two pistons 44 and 45 further rod 50, 51, the z. B. leads to a manually operated lever, the brakes can optionally be operated directly by the driver of the vehicle even when the motor pressure pump is at a standstill. The same linkage also acts on the rear side of the piston in this exemplary embodiment

44 arranged in the space 49 spring 52, which is mainly used to also when in the rest position Control member 24 on the piston 44 resting differential force corresponding to the constant overpressure in Pressure medium to counteract the cross section of the piston rod 47 and at the same time the piston friction to overcome when releasing the brake.

Finally, FIG. 5 shows a modified embodiment of the control element 24 for the brake actuation by the pedal 21 and a linkage 22. In this case, the control member is as longitudinally movable Formed slide, which in the illustrated braking position through the control edge 53 through the line 5 entering pressure medium the way to the wheel brake cylinders 26, 27 or one of the master cylinder mechanically actuating working cylinder releases and simultaneously with the control edge 54 shut off the Drackleitungsverlängerang 5 '. With increasing travel of the brake pedal 21 is of the collar 55 of the control slide of the ring body 56, a pressure relief valve between the pressure line 5 and the return line 37 'moved to the left in its guide cylinder 57 and thereby the Valve spring 58 stretched. The valve spring 58 is dimensioned so that it is in the rest position of the control member 24, d. H. in the right end position, has only very little or no pretension at all, the pressure medium for releasing the brakes as easily as possible from the brake cylinders into the return line 37 'to drain. Each increase in the deflection on the pedal 21 increases the tension of the valve spring 58 and thus also the pressure acting on the brake cylinder and the pressure corresponding thereto Braking force increased, so that with such a control member an arbitrarily finely graded Braking effect can be achieved.

Claims (5)

PATENT CLAIMS: 1. Hydraulic system for motor vehicles, especially tractors, with a pressure pump driven by the vehicle engine and at least one working device in the form of a working cylinder and / or liquid motor, which is dimensioned for a relatively high fluid pressure and in which a pressure relief valve is switched on in the return line for the pressure fluid from the working devices to maintain a permanent low overpressure in the interior of a continuously variable fluid transmission connected to the hydraulic system, according to patent 1022917, characterized in that one or more high-pressure working cylinders (26, 27, 30, 31 and 43) as brake cylinders of the Vehicle brake system are formed and a control member (24) is provided by which the working pressure in the brake cylinders can be regulated. 2. Hydraulic system according to claim 1, characterized in that the piston (44) in the from the pressure pump acted upon working cylinder (43) for the brake actuation in itself known way with a constant low overpressure in the pressure medium system Equilibrium-maintaining spring (52) is in operative connection. 3. Hydraulic system according to claim 1 or 2, characterized in that the piston (44) in the working cylinder, which can be acted upon by the pressure pump, for the brake actuation in in a manner known per se with its rear side on a likewise filled with the pressure medium Space (49) borders, which is constantly with the return line under slight overpressure (37 ', 10) is connected. 4. Hydraulic system according to claim 1, 2 or 3, characterized in that the control member (24) for the brake actuation in the first place in the pressure line coming from the pressure pump (1) (5) is switched on and in a known manner when applying the brake to the Control slide (6) for pressure line (5 ') leading to further high-pressure work devices shut off. 5. Hydraulic system according to one or more of claims 1 to 4, characterized in that that a pressure relief valve (55, 56, 57) is connected in parallel to the control member (24) for the brake actuation in a manner known per se which has a response pressure that can be changed as a function of the brake pedal position. Considered publications: German Patent Specifications Nos. 402 589, 691 044; Austrian Patent Specification No. 182616,185691; Swiss Patent No. 222412; British Patent Nos. 622,617, 752,585; U.S. Patents Nos. 1,944,002, 2,004,078, 002, 2624 361. 1 sheet of drawings ® 109 709/246 10.61