DE102018007007A1 - Hydraulic system, in particular for vehicles used for military purposes - Google Patents

Abstract

A hydraulic system, in particular for vehicles used for military purposes, with at least two functional units, one of which represents a supply unit (2) and another represents a consumer unit (4), which, spatially separated from one another, are in part exposed to the same, but in particular different, ambient temperatures If a temperature limit value is exceeded, the evaporation of a water-based flame-retardant liquid according to its vapor pressure curve, by means of which the hydraulic system can be operated, is characterized in that there is a pretensioning device (42; 52) which is used to vaporize the liquid when the temperature limit value is exceeded to prevent the operating pressure in the hydraulic system increases according to the vapor pressure curve of the liquid.

Description

The invention relates to a hydraulic system, in particular for vehicles used for military purposes, with at least two functional units, one of which represents a supply unit and another represents a consumer unit, which, spatially separated from one another, are in part exposed to the same, but in particular different, ambient temperatures which are exceeded when one Temperature limit value for evaporation of a water-based flame-retardant liquid according to their vapor pressure curve, by means of which the hydraulic system can be operated.

As exemplified in EP 0 185 871 A1 military vehicles, such as battle tanks, armored personnel carriers or team transport vehicles, have hydraulic systems which define their essential functions via hydraulically actuated actuation systems, such as piston-cylinder units which adjust the firing position of weapon barrels, travel drives, opening and closing systems for armored doors, covers and the like. In the event of a bombardment of such vehicles in combat situations, damage to a hydraulic system which works with an easily flammable fluid, such as hydraulic oil, as the operating medium, poses a considerable risk. To counter this, a water-based, flame-retardant liquid can be used instead of hydraulic oil Operating medium can be used. According to the vapor pressure curve of water-based fluids and considering that the function units of the hydraulic system are generally located in different rooms in vehicles used for military purposes, especially armored vehicles, if the temperature limit is exceeded in one or both rooms, the liquid can evaporate. The advantage of the substantially reduced fire risk when using the flame-retardant, water-based fluids is therefore offset by the disadvantage that evaporation leads to compressibility of the operating medium and thus has negative effects on the operating behavior of the hydraulic system.

In view of this problem, the object of the invention is to provide a hydraulic system of the type mentioned at the outset which, when operated with a water-based fluid which reduces the risk of fire, is distinguished by a particularly favorable operating behavior.

According to the invention, this object is achieved by a hydraulic system which has the features of claim 1 in its entirety.

According to the characterizing part of claim 1, an essential special feature of the invention is that a pretensioning device is provided which, in order to prevent the liquid from evaporating when the temperature limit is exceeded, increases the operating pressure in the hydraulic system in accordance with the vapor pressure curve of the liquid. The security against evaporation achieved by the preload enables trouble-free operation with flame-retardant, water-based operating media, even in areas of application in which the functional unit temperatures are to be expected, as is the case with armored vehicles in particular. An HFC fluid which is commercially available can advantageously be used as the flame-retardant hydraulic fluid. This fluid is biodegradable and meets the requirements of DIN EN ISO 12922 for flame-retardant liquids. The solution according to the invention can be used in particular for armored military vehicles, the term vehicles also being intended to include planes, ships, submarines and the like.

If the hydraulic system according to the invention is intended for applications in which only the consumer unit, for example in the engine compartment of the vehicle in question, is possibly exposed to a temperature above the limit value, while the supply unit, for example in the crew compartment of the vehicle in question, does not run the risk of one To be exposed to evaporation of the fluid-carrying temperature, the pretensioning device coming from the consumer unit can be connected in a return line, the pretensioning device having a pretensioned, preferably hermetically sealing check valve which closes in the direction of the consumer unit and opens in the opposite direction. When the check valve is set to an opening pressure that is above the steam point of the steam pressure curve, the system remains at the pre-tension pressure provided by the supply unit when the return flow is blocked.

If the hydraulic system is intended for operations in which both the supply unit, for example in the vehicle's crew compartment, and the consumer unit, such as in the engine compartment of the vehicle, can be exposed to a temperature above the evaporation temperature, the arrangement is advantageously made such that that the supply unit has a pressure-resistant storage container which, as a pretensioning device, has an air inlet valve with an opening pressure greater than 1 bar absolute, which allows the air to flow freely into the container when the liquid is removed in the direction of the consumer unit and when the liquid is returned to the container Air only at a specifiable pressure in allows the environment to flow out, the pressure value of which is selected in accordance with the vapor pressure curve in relation to the temperature limit value. By choosing the opening pressure of the air inlet valve in the outflow direction, a preload pressure can be built up by the supply unit, which is above the steam point for the maximum occurring ambient temperature in one or the other room.

For applications in which temperatures above the steam point are to be expected for the rooms of the supply unit and the consumer unit, for example the crew room and the engine room, in addition to the prestressing of the pressure-resistant storage container in a return line, a prestressed, preferably hermetic, coming from the consumer unit sealing check valve is provided, which closes in the direction of the consumer unit and opens in the opposite direction. The opening pressure of this valve is set to the value of the vapor pressure curve corresponding to the maximum temperature that occurs.

The check valve inserted into the return line in each case can be arranged outside the storage container, preferably in a receiving bore of the supply unit, which has the storage container as a component.

In advantageous exemplary embodiments, a pressure storage unit is arranged between the supply unit and the consumer unit. When the system is at a standstill, the prestressing pressure preventing the evaporation of the liquid in the closed system is available from the pressure storage unit.

The supply unit is designed such that the operation of the pressure built up in a supply line for the consumer unit by means of the supply unit is so high that evaporation of the liquid is prevented.

• - eine Druckversorgungspumpe,
• - einen Leitungsfilter,
• - optional ein vorgespanntes Rückschlagventil,
• - optional ein Lufteinlassventil,
• - ein Sicherheitsventil und/oder ein Druckbegrenzungsventil zur Absicherung der Druckversorgungspumpe.

The supply unit has the following components for this:

• - a pressure supply pump,
• - a line filter,
• - optionally a preloaded check valve,
• - optionally an air inlet valve,
• - A safety valve and / or a pressure relief valve to protect the pressure supply pump.

The consumer unit can have at least one hydraulically actuated working cylinder.

At least one hydraulic accumulator can be provided for the accumulator unit, which can be a bladder accumulator, piston accumulator or an accumulator of another design.

The supply unit and / or the storage unit can be accommodated in a crew compartment of the armored vehicle, while the consumer unit can be located in its engine compartment.

• 1 in Symboldarstellung die hydraulische Schaltung einer ersten Ausführungsform der erfindungsgemäßen hydraulischen Anlage;
• 2 und 3 in Symboldarstellung die hydraulische Schaltung einer zweiten bzw. dritten Ausführungsform der erfindungsgemäßen Anlage;
• 4 in Symboldarstellung die gesondert gezeigte Versorgungseinheit der Ausführungsform von 3; und
• 5 die Dampfdruckkurve für HFC-Fluid.

The invention is explained in detail below with reference to the drawing.
Show it:

• 1 in symbolic representation, the hydraulic circuit of a first embodiment of the hydraulic system according to the invention;
• 2 and 3 the hydraulic circuit of a second or third embodiment of the system according to the invention in symbolic representation;
• 4 in a symbolic representation, the separately shown supply unit of the embodiment of 3 ; and
• 5 the vapor pressure curve for HFC fluid.

The embodiments of the hydraulic system according to the invention shown in the figures each have a supply unit 2 , a consumer unit 4 , a storage unit 6 as well as a control block 8th on. The consumer unit 4 is in a room 10 by a room 12 is spatially separated, in which the supply unit 2 , the storage unit 6 as well as the control block 8th are located. The rooms 10 and 12 , which are the engine room or the crew room of a military vehicle in the present example, can have different ambient temperatures during operation in the spatial separation. In the examples shown in the figures, the consumer unit points 4 hydraulically actuated working cylinders 14 on that through a common work management 16 with the control block 8th are connected, in which HFC fluid flows in the forward or reverse direction for the cylinder actuation. When using the hydraulic system in military vehicles, the supply unit 2 , the storage unit 6 and the control block 8th receiving team room 12 Ambient temperatures up to 80 ° C occur while it is in the engine room 10 can reach maximum temperatures up to 160 ° C. In both rooms 10 and 12 the temperature of the evaporation point of 60 ° C can therefore be exceeded when using HFC fluid.

The supply unit 2 has a reservoir made of an HFC fluid in all embodiments 18th priming motor-pump unit 20th on that through a line filter 22 at a pressure port P provides a supply pressure that prevents evaporation at the maximum temperatures that occur. The pressure port P is via a supply line 24 with the storage unit 6 associated with their home page 26 on the control block 8th connected. The storage unit 6 is constructed in the usual way and has a pressure accumulator 28 on, the oil side via a check valve 30th with the supply line 24 and a check valve 32 with the exit side 26 is connected, the check valves 30th . 32 open in the direction of advance. Via a pressure relief valve forming an overpressure safety device 34 and a manually operated drain valve that enables emptying 36 is the pressure accumulator 28 also with a return line 38 connected to the tank connection T the supply unit 2 and thus via one in the supply unit 2 located tank line 40 in the storage container 18th leads. The exit side 26 the storage unit 6 is via a flow line 44 with one in the control block 8th located switching valve 46 in connection with which also the return line 38 connected is. The switching valve 46 is designed as a 3/2-way valve that can be controlled electromagnetically in order to actuate the working cylinder 14 the lead pipe 44 or the return line 38 over the work management 16 with the cylinders 14 connect to.

The embodiment of 1 is intended for use in which in the room 10 , as the engine room of the vehicle in question, ambient temperatures may prevail that are above the vapor point temperature of 60 ° C of the HFC fluid while in the room 12 than the team room 12 an ambient temperature of 60 ° is not exceeded. In this case, the pretensioner is inserted into the return line 38 inserted valve 42 formed, which is a hermetically sealed check valve that towards the working cylinder 14 closes. Against opening in the return direction, i.e. from the consumer unit 4 to the tank connection T , is the valve 42 biased such that it only opens at a pressure above the pressure at which evaporation occurs at the maximum temperature. This remains, even if the switching valve 46 is switched to return from the supply unit 2 applied pressure as preload pressure in the room 10 receive related system part. The embodiment of FIG 1 through a ventilation line 48 from the reservoir 18th via a ventilation connection B of the supply unit 2 and a ventilation filter 50 leads to the environment. In 1 are two optional ways of arranging the valve 42 shown. The valve 42 can outside the supply unit 2 in the return line 38 can be inserted or the supply unit 2 be assigned, it being in the bore of the T-connection of the tank line 40 can be used.

The second embodiment, as in 2 is shown is intended for use in which in operation in both rooms 10 and 12 the same ambient temperature prevails, which is above the limit for HFC fluid and can be, for example, up to 80 ° C, the highest in the team room 12 occurring ambient temperature. In this case, the fluid reservoir 18th formed by a closed, pressure-resistant container on which an air inlet valve acts as a pretensioning device 52 is connected, that at an opening pressure that is below 1 bar absolute and, for example, 0.5 bar, air through the ventilation filter 50 and the ventilation line 48 free in the closed storage container 18th can flow, if liquid is taken from this, over the supply line 24 to the storage unit 6 and to the consumer unit 4 to pour. With liquid return via the return line 38 and the tank line 40 blocks the inlet valve 52 however, until a selected one is reached, in the storage container 18th built up pressure, which prevents evaporation. The entire system in the rooms 10 and 12 is biased with the same pressure.

The 3 shows a third embodiment, which is designed for applications in which in both rooms 10 and 12 Temperatures above 60 ° C can occur, being in the engine room 10 However, the prevailing temperature in the team room 12 prevailing temperature. In this case, it is not necessary to use the entire system as with 2 , to the maximum temperature of the room 10 to interpret. In other words, it means that the pressure-resistant reservoir 18th in terms of its compressive strength, in terms of wall thickness and weight, it does not have to be designed for a container pressure that corresponds to the pressure value for those in the room 10 possible maximum temperature corresponds, but can be designed for the tank pressure, that of the team room 12 occurring, lower temperature corresponds. For this purpose, is in correspondence to 2 , the closed storage container 18th with the air intake valve 52 provided, which is set to an outlet opening pressure which is the maximum temperature in the crew room 12 is adjusted. However, for the in the engine room 10 to provide a correspondingly higher pretensioning pressure for the system part located with a higher ambient temperature is in the embodiment of 3 , corresponding to the embodiment of 1 , in the return line 38 the preloaded check valve 42 arranged, which is set for a correspondingly higher opening pressure in the return direction, so that, as in the example of 1 by the supply unit 2 provided pressure remains as bias pressure even when the switching valve 46 is switched to reverse. As in the example of 1 , the valve 42 into the supply unit 2 integrated or external to the return line 38 be used.

The one with its exit page 26 with the flow line 44 connected storage unit 6 provides even when the motor-pump unit is at a standstill 20th a preload pressure is available which prevents the evaporation of the fluid if a correspondingly high ambient temperature occurs. The 4 shows details of the training of the supply unit 2 for embodiments in which the closed storage container 18th has a volume of more than 1 liter, which is usually the case. Then the reservoir must be used at the pre-tensioning pressures that are considered here 18th be designed as a pressure device according to the pressure device line 2014/68 / EU and therefore have a safety valve. As in 4 shown is a pressure relief valve for this 54 on the ventilation line 48 connected. How 4 further shows is another pressure relief valve 56 between the printed page 58 the motor pump unit 20th and the line filter 22 switched, the input side against reverse flow through a check valve 60 is secured. A bypass valve 62 is as a bypass of the line filter 22 intended.

The 5 shows the vapor pressure curve for a special HFC fluid as hydraulic medium in a simplified, not numbered representation. As can be seen, the temperature value of the evaporation is 60 ° C in the absence of a preload pressure. It goes without saying that the temperature value of the evaporation may be different for other HFC liquids used, for example may also exceed the value of 60.degree.

QUOTES INCLUDE IN THE DESCRIPTION

This list of documents listed by the applicant has been generated automatically and is only included for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• EP 0185871 A1 [0002]

Non-patent literature cited

• DIN EN ISO 12922 [0005]

Claims (10)

Hydraulic system, in particular for vehicles used for military purposes, with at least two functional units, one of which represents a supply unit (2) and another represents a consumer unit (4), which, spatially separated from one another, are in part exposed to the same, but in particular different, ambient temperatures that occur at Exceeding a temperature limit lead to the evaporation of a water-based flame-retardant liquid according to its vapor pressure curve, by means of which the hydraulic system can be operated, characterized in that a pretensioning device (42; 52) is present which is used to prevent the liquid from evaporating when the temperature limit is exceeded , the operating pressure in the hydraulic system is increased in accordance with the vapor pressure curve of the liquid. Hydraulic system after Claim 1 , characterized in that the supply unit (2) has a pressure-resistant storage container (18) which, as the pretensioning device, has an air inlet valve (52) with an opening pressure greater than 1 bar absolute, which releases the air when the liquid is removed in the direction of the consumer unit (4) can flow into the container (18) and, when the liquid is returned to the container (18), the air can only flow out into the environment at a predeterminable pressure, the pressure value of which is selected in accordance with the vapor pressure curve, based on the temperature limit value. Hydraulic system after Claim 1 or 2 , characterized in that in a return line (38) coming from the consumer unit (4), the pretensioning device is connected, which has a pretensioned, preferably hermetically sealing check valve (42) which closes in the direction of the consumer unit (4) and opens in the opposite direction . Hydraulic system according to one of the preceding claims, characterized in that the check valve (42) inserted into the return line (38) is arranged outside the storage container (18), preferably in a receiving bore (T) of the supply unit (2) which is used as has a component of the reservoir (18). Hydraulic system according to one of the preceding claims, characterized in that a pressure storage unit (6) is arranged between the supply (2) and consumer unit (4). Hydraulic system according to one of the preceding claims, characterized in that the pressure built up in operation in a supply line (24) for the consumer unit (4) by means of the supply unit (2) is so high that evaporation of the liquid is prevented. Hydraulic system according to one of the preceding claims, characterized in that the supply unit (2) has the following components: - a pressure supply pump (20), - a line filter (22), - optionally a preloaded check valve (42), - optionally an air inlet valve ( 52), - a safety valve and / or a pressure limiting valve (56) for securing the pressure supply pump (20). Hydraulic system according to one of the preceding claims, characterized in that the consumer unit (4) has at least one hydraulically actuated working cylinder (14). Hydraulic system according to one of the preceding claims, characterized in that the storage unit (6) has at least one hydraulic accumulator (28). Hydraulic system according to one of the preceding claims, characterized in that the supply unit (2) and / or the storage unit (6) are accommodated in a crew compartment (12) of the vehicle used for military purposes and the consumer unit (4) in its engine compartment (10).

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