Use of a hydraulic system with a hydraulic line for hydraulic actuation in a motor vehicle

Abstract

Use of a hydraulic system (10) for multiple parallel hydraulic actuations in a motor vehicle, comprising a first hydraulic section (22) and a second hydraulic section (24), wherein the first hydraulic section (22) and / or the second hydraulic section is designed as a hydraulic section (22, 24, 26, 28) for hydraulic actuation in the motor vehicle, comprising a pressure source (12) for generating a hydraulic pressure, a pressure consumer (14) for hydraulically applying force, and a pressure line (16) for hydraulically connecting the pressure source (12) to the pressure consumer (14), wherein the pressure consumer (14) has components with a lower temperature load limit than the pressure source (12) and the pressure line (16), wherein a hydraulic consumer volume of the pressure consumer (14) is smaller than a line volume (VL, VS1, VS2, VS3, VS4) of the pressure line (16) between the pressure source (12) and the pressure consumer (14) is,wherein the first hydraulic line (22) and the second hydraulic line (24) share the identical pressure source (12) for roll stabilization of the motor vehicle and for height adjustment of the motor vehicle.,

Description

[0001] The invention relates to a use of a hydraulic system with a hydraulic section, with the aid of which a hydraulic actuation can be carried out in a motor vehicle.

[0002] From EP 2 186 662 A1 a hydraulic system for a motor vehicle is known in which several wheel suspensions can be hydraulically actuated from a common pressure source, wherein in the event that a hydraulic medium in one of the wheel suspensions is heated too much, the hydraulic medium is exchanged and mixed with the hydraulic medium in a less heated wheel suspension.

[0003] From Breuer, Bert; Bill, Karlheinz H. (eds.): Brake Handbook: Fundamentals, Components, Systems, Driving Dynamics. 5th, revised and expanded edition. Wiesbaden: Springer, 2017 (ATZ / MTZ textbook). pp. 105, 109, 134. ISBN 978-3-658-15489-9. https: / / doi.org / 10.1007 / 978-3-658-15489-9, a hydraulic system for operating the wheel brakes of a motor vehicle is known, in which the wheel brake can be hydraulically actuated from a pressure source via a pressure line.

[0004] There is a constant need to prevent thermal damage to hydraulic pressure consumers in a motor vehicle.

[0005] It is the object of the invention to show measures that enable good protection of hydraulic pressure consumers in a motor vehicle against thermal damage.

[0006] The object is achieved according to the invention by a use with the features of claim 1. Preferred embodiments of the invention are specified in the subclaims and the following description, which may each individually or in combination represent an aspect of the invention.

[0007] One aspect of the invention relates to the use of a hydraulic system for multiple parallel hydraulic actuations in a motor vehicle, comprising a first hydraulic section and a second hydraulic section, wherein the first hydraulic section and / or the second hydraulic section is designed as a hydraulic section for hydraulic actuation in the motor vehicle, comprising a pressure source for generating a hydraulic pressure, a pressure consumer for hydraulically applying force, and a pressure line for hydraulically connecting the pressure source to the pressure consumer, wherein the pressure consumer has components with a lower temperature load limit than the pressure source and the pressure line, wherein a hydraulic consumer volume of the pressure consumer is smaller than a line volume of the pressure line between the pressure source and the pressure consumer,wherein the first hydraulic line and the second hydraulic line share the identical pressure source, for roll stabilization of the motor vehicle and for height adjustment of the motor vehicle.,

[0008] It has been recognized that thermal stress on the pressure consumer can be caused by the hydraulic medium heated in the pressure source when the pressure is built up. In order to thermally protect the pressure consumer, it is intended that the hydraulic medium heated in the pressure source cannot reach the pressure consumer at all. This is achieved by the line volume of the pressure line being so large that only the hydraulic medium in the pressure line before the pressure source is operated can reach the pressure consumer. The hydraulic medium in the pressure line before the pressure source is operated has a significantly lower temperature than the hydraulic medium pumped by the pressure source, since the energy input caused by the pressure source during the hydraulic pressure build-up is only transferred to the hydraulic medium passing through the pressure source.The cold medium previously present in the pressure line can thus form a thermal buffer, which, due to its volume, can prevent contact between the hot hydraulic medium delivered by the pressure source and the components of the pressure consumer. Due to the thermal buffer effect of the large line volume, hydraulic medium heated by the pressure source cannot reach the pressure consumer, thus ensuring good protection of hydraulic pressure consumers in a motor vehicle against thermal damage.

[0009] The pressure source can be configured as a hydraulic pump that pressurizes the hydraulic medium supplied from a reservoir and increases the hydraulic pressure at the hydraulic pump's outlet. The pressure line can be directly connected to the pressure source's outlet and receive the pressurized hydraulic medium. The pressure source is designed especially for higher temperatures, for example, greater than 90°C or greater than 100°C.

[0010] The hydraulic medium is, in particular, a hydraulic oil, for example, HLP according to DIN 51 524 Part 2. The hydraulic medium is particularly air- and water-separating and suitable, for example, for pressures of up to 200 bar or up to 350 bar. Preferably, the hydraulic medium has a lower thermal conductivity than water and / or HLP.

[0011] The pressure line is designed for the pressures and temperatures occurring at the outlet of the pressure source. In particular, the pressure line has a temperature load limit of over 90°C, especially over 100°C. Furthermore, the pressure line can be designed for a hydraulic pressure of up to 200 bar or up to 350 bar. The pressure line can be designed as a reinforced hydraulic hose or metal pipe.

[0012] The pressure consumer can be configured for hydraulic actuation, for example, by the hydraulic pressure arriving at the pressure consumer pressing against a pressure plate of an actuator provided in the pressure consumer for relative movement. A valve leg of the actuator can be connected to a hydraulically displaceable motor vehicle component. In particular, the pressure consumer is provided for adjusting the height of a wheel of the motor vehicle relative to a body of the motor vehicle.

[0013] The components of the pressure consumer may, at least in part, have a relatively low temperature load limit. In particular, seals within the pressure consumer, which are intended to seal parts that move relative to each other, have a low temperature load limit and could be permanently damaged at temperatures above the temperature load limit. This can occur, for example, at temperatures below 100°C or below 90°C.

[0014] The temperature load limit represents a maximum possible temperature at which permanent thermal damage to the component is not to be expected.

[0015] In particular, the pressure line is made of a rigid pipe material, wherein the pressure consumer comprises a hose made of an elastic and / or flexible hose material and connected to the pressure line, wherein the hose material has a lower temperature load limit than the pipe material. The pipe material, for example steel, can withstand high pressures and high temperatures and is therefore well suited as a pressure line. The pressure consumer may have to undergo a relative movement together with the hydraulically moved motor vehicle component and can therefore be connected to the pressure line via the hose, so that due to the flexible and / or elastic nature of the hose, a relative movement of the two ends of the hose to each other can be permitted.However, to ensure sufficient flexibility and / or elasticity, the hose material usually contains plasticizers that can lose their plasticizing effect at higher temperatures, causing the hose material to become brittle and be damaged during movement. However, since the large line volume prevents excessively high temperatures in the hose, there is no risk of thermal damage to the hose. In fact, the large line volume makes it possible to use a hose in the pressure consumer and / or to mount the pressure consumer in a way that moves with the vehicle component to be adjusted. This can increase the degree of design freedom when designing hydraulically operated vehicle components.

[0016] The pressure consumer preferably has a relatively movable actuator, wherein the actuator is sealed in the pressure consumer by means of a seal, wherein the seal has a lower temperature load limit than the pressure line and the pressure source. In particular, the seal sealing the relatively movable actuator is generally comparatively soft and not very temperature-resistant. However, since the large line volume can prevent excessively high temperatures at the seal, the seal can be selected and dimensioned based on its sealing properties rather than its temperature resistance. This can improve the sealing effect in the pressure consumer at lower manufacturing costs. At the same time, a long service life for the pressure consumer can be achieved.

[0017] Particularly preferably, the pressure source is configured to heat a hydraulic medium to a temperature above 90°C, in particular above 100°C, for operating the pressure consumer. The pressure consumer comprises components with a maximum temperature load limit of below 90°C, in particular below 85°C, preferably below 80°C. The pressure source can be designed for comparatively high temperatures and high pressures, but due to the thermal buffer effect of the large line volume, the pressure consumer only needs to be designed for significantly lower temperatures. This can reduce manufacturing costs.

[0018] In particular, the pressure line has a longer extension than a direct linear distance between the pressure consumer and the pressure source. The large pressure line volume intended for the thermal buffering effect can be achieved by an extended route, for example, a square, zigzag, and / or looped one. This avoids increasing the flow cross-section in the pressure line. In fact, it is actually advantageous rather than disadvantageous if the pressure line has a more complex route, routing around various fixtures, as this actually improves the buffering effect of the line volume.

[0019] Preferably, the pressure line has a longer extension than a perpendicular run between the pressure consumer and the pressure source. The large volume of the pressure line intended for the thermal buffering effect can be achieved by an extended route, for example, a zigzag and / or loop-shaped one. This avoids increasing the flow cross-section in the pressure line. In fact, it is even advantageous rather than disadvantageous if the pressure line has a more complex route, routing around various fixtures, as this actually improves the buffering effect of the line volume.

[0020] Particularly preferably, the line volume is selected to be large enough relative to the consumer volume that, in a maximum actuated end position of the pressure consumer, a buffer volume remains between the pressure consumer and a medium volume in the pressure line that has previously passed the pressure source to compensate for heat conduction effects with a medium that has not previously passed the pressure source. Even in the maximum actuated end position of the pressure consumer, the line volume of the pressure line is not completely filled with the hot hydraulic medium from the pressure source. Instead, the cold hydraulic medium that has not passed through the pressure source remains in a section that ends at the pressure consumer. The buffer volume is, for example, 1% to 15%, in particular 2% to 10% of the total line volume.The hot hydraulic medium can heat the cold hydraulic medium in the buffer volume through heat conduction. However, the buffer volume can be selected so large that, even taking heat conduction effects along the length of the pressure line into account, no temperature can occur in the pressure consumer that exceeds the temperature load limit. The hydraulic medium in the pressure consumer thus has a temperature that can be safely below the temperature load limit.

[0021] In particular, the first hydraulic line and the second hydraulic line share at least part of the identical pressure line. Sharing common components reduces the number of components and manufacturing costs.

[0022] In particular, a third hydraulic line, which can be designed and developed in particular as described above, and a fourth hydraulic line, which can be designed and developed in particular as described above, are provided, wherein either the first hydraulic line and the second hydraulic line or the third hydraulic line and the fourth hydraulic line share at least part of the identical pressure line. The pressure source can act on two hydraulic lines leading, for example, to rear wheels or front wheels, in particular in the region of the associated wheel axle, wherein the hydraulic lines spaced apart from the pressure source are connected to the pressure source via a common part of the pressure line. The common part of the pressure line can in particular bridge an offset of a front wheel axle to a rear wheel axle.

[0023] The invention will be explained below by way of example with reference to the accompanying drawings using a preferred embodiment, wherein the features presented below can represent an aspect of the invention both individually and in combination. It shows: Fig. 1: a schematic diagram of a hydraulic system for roll stabilization and height adjustment of a motor vehicle.

[0024] The Fig.1. A hydraulic system 10 provided for roll stabilization and height adjustment of a motor vehicle comprises a pressure source 12 configured as a hydraulic pump, which can pressurize a hydraulic medium and, in doing so, significantly heat the hydraulic medium. The hydraulic pressure can be applied to the respective pressure consumers 14 via a pressure line 16 connected to the pressure source 12 and leading to up to four pressure consumers 14 acting on wheels of the motor vehicle. Each pressure consumer 14 comprises an actuator 18 acting on the associated wheel of the motor vehicle and a hose 20 connecting the actuator 18 to the pressure line 16.

[0025] With the help of the pressure line 16, a first hydraulic section 22 and a second hydraulic section 24 are formed, which share the same pressure source 12 and a common part of the pressure line 16. A line volume Vs of the first hydraulic section 22 consists of half of the common part of the pressure line V L / 2 and the non-shared part of the pressure line V S1 whose sum is smaller than the consumer volume of the pressure consumer 14 of the first hydraulic section 22 formed by the actuator 18 and the hose 20. A line volume Vs of the second hydraulic section 24 consists of half of the common part of the pressure line V L / 2 and the non-shared part of the pressure line V S2whose sum is smaller than the consumer volume of the pressure consumer 14 of the second hydraulic line 24 formed by the actuator 18 and the hose 20. A third hydraulic line 26 and a fourth hydraulic line 28 are connected to the pressure source 12 via separate pressure lines 16. A line volume V S3 of the third hydraulic line 26 is smaller than the consumer volume of the pressure consumer 14 of the third hydraulic line 26 formed by the actuator 18 and the hose 20. A line volume V S4of the fourth hydraulic section 28 is smaller than the consumer volume of the pressure consumer 14 of the fourth hydraulic section 28 formed by the actuator 18 and the hose 20. The respective line volume of the respective hydraulic section 22, 24, 26, 28 is so large compared to the associated consumer volume that no hydraulic fluid heated by the pressure source 12 can reach the respective pressure consumer 14. Thermal damage to the pressure consumer 14, which is designed for a significantly lower temperature load limit, can be avoided.

Claims

[1] Use of a hydraulic system (10) for a plurality of parallel hydraulic actuations in a motor vehicle, with a first hydraulic section (22) and a second hydraulic section (24), wherein the first hydraulic section (22) and / or the second hydraulic section is designed as a hydraulic section (22, 24, 26, 28) for a hydraulic actuation in the motor vehicle, with a pressure source (12) for generating a hydraulic pressure, a pressure consumer (14) for hydraulically applying force and a pressure line (16) for hydraulically connecting the pressure source (12) to the pressure consumer (14), wherein the pressure consumer (14) has components with a lower temperature load limit than the pressure source (12) and the pressure line (16), wherein a hydraulic consumer volume of the pressure consumer (14) is less than a line volume (V L , V S1 , V S2 , V S3 , VS4 ) of the pressure line (16) between the pressure source (12) and the pressure consumer (14), wherein the first hydraulic section (22) and the second hydraulic section (24) share the identical pressure source (12), for roll stabilization of the motor vehicle and for height adjustment of the motor vehicle. [2] Use according to claim 1, wherein the pressure line (16) is made of a rigid pipe material, wherein the pressure consumer (14) has a hose (20) made of an elastic and / or flexible hose material and connected to the pressure line (16), wherein the hose material has a lower temperature load limit than the pipe material. [3] Use according to claim 1 or 2, wherein the pressure consumer (14) has a relatively movable actuator (18), wherein the actuator (18) is sealed by means of a seal in the pressure consumer (14), wherein the seal has a lower temperature load limit than the pressure line (16) and the pressure source (12). [4] Use according to one of claims 1 to 3, wherein the pressure source (12) is adapted to actuate the pressure consumer (14) to heat a hydraulic medium to a temperature of above 90°C, in particular above 100°C, wherein the pressure consumer (14) has components with a maximum temperature load limit of below 90°C, in particular below 85°C, preferably below 80°C. [5] Use according to one of claims 1 to 4, wherein the pressure line (16) has a longer extension compared to a direct linear distance of the pressure consumer (14) to the pressure source (12). [6] Use according to one of claims 1 to 5, wherein the pressure line (16) has a longer extension compared to a right-angled course between the pressure consumer (14) and the pressure source (12). [7] Use according to one of claims 1 to 6, wherein the line volume (V L , V S1 , V S2 , V S3 , V S4 ) relative to the consumer volume is selected to be so large that, in a maximum actuated end position of the pressure consumer (14), a buffer volume remains between the pressure consumer (14) and a medium volume located in the pressure line (16) and previously passing the pressure source (12) to compensate for heat conduction effects with medium that has not previously passed the pressure source (12). [8] Use according to one of claims 1 to 7, wherein the first hydraulic section (22) and the second hydraulic section (24) share at least part of the identical pressure line (16). [9] Use according to one of claims 1 to 8, wherein a third hydraulic section (26) and a fourth hydraulic section (28) are provided, wherein either the first hydraulic section (22) and the second hydraulic section (24) or the third hydraulic section (26) and the fourth hydraulic section (28) share at least part of the identical pressure line (16).

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