DE102013011565A1 - Fluid circuit of a motor vehicle - Google Patents

Abstract

The invention relates to a fluid circuit (1) of a motor vehicle, comprising a primary circuit (2) having a fluid pump (3) and a heat consumer (4) and having a secondary circuit (6) which contains a heat accumulator (7) and the primary circuit (2). is fluidically connected in parallel, wherein the secondary circuit (6) has at least one switching valve (12) which releases a flow connection through the secondary circuit (6) in a first switching position and interrupts in a second switching position. It is provided that the secondary circuit (6) via a jet pump (14) is fluidically connected to the primary circuit (2).

Description

The invention relates to a fluid circuit of a motor vehicle, having a fluid pump and a heat consumer having primary circuit and a secondary circuit containing a heat storage and the primary circuit fluidly connected in parallel, wherein the secondary circuit has at least one switching valve in a first switching position a flow connection releases the secondary circuit and interrupts in a second switching position.

The fluid circuit may be any circuit of the motor vehicle in which, at least at times, a fluid circulates for the transport of heat. For example, the fluid circuit is in the form of a cooling circuit, so that a coolant is used as the fluid. The fluid circuit has at least the primary circuit and the secondary circuit, wherein the primary circuit is preferably continuously traversed by the fluid during operation of the fluid circuit. By contrast, the secondary circuit serves to temporarily store heat from the primary circuit, so that it is preferably operated only in sections, in particular for loading and / or unloading the heat accumulator.

The primary circuit has the fluid pump and the heat consumer. The fluid pump serves to circulate the fluid in the primary circuit. The heat consumer, for example, in the form of a heat exchanger, for example, as passenger compartment heating of the motor vehicle. The secondary circuit, however, has the heat storage or is designed as a heat storage. In this case, the secondary circuit or the heat storage of the primary circuit at least partially fluidically connected in parallel. This means that the secondary circuit branches off at a first branch from the primary circuit and opens at a second branch back into it.

It can now be provided, for example, that with the aid of the fluid pump in a first operating mode, the fluid is circulated only in the primary circuit. In a second mode, however, it is provided to direct the fluid through the secondary circuit and thus the heat storage, so that the heat storage is either loaded with the primary circuit heat removed or alternatively the primary circuit supplies heat, that is discharged.

For example, it is provided to interrupt a flow connection through the primary circuit between the first branch and the second branch, so that the fluid does not pass from the first branch through the primary circuit to the second branch, but that it must flow through the secondary circuit or the heat storage , In such an embodiment of the fluid circuit, however, numerous switching valves are necessary. In addition, during the discharge of the heat accumulator or the discharge of the heat stored in the heat accumulator to the primary circuit, a sudden and strong increase in temperature in the primary circuit may occur.

It is an object of the invention to provide a fluid circuit of a motor vehicle, in which the number of switching valves can be reduced and / or the occurrence of the sharp rise in temperature is largely avoided.

This is achieved according to the invention with a fluid circuit having the features of claim 1. It is provided that the secondary circuit is fluidly connected via a jet pump to the primary circuit. By the jet pump is meant a pump in which the pumping action is generated by a jet of fluid. It is provided to operate by means of the fluid pump, the primary circuit such that the jet pump circulating in the primary circuit fluid is supplied as a driving medium. This driving medium is used to generate a negative pressure in the jet pump, whereby the present in the secondary circuit or the heat accumulator fluid is sucked in, provided that a flow connection is released through the secondary circuit.

The jet pump has, for example, a motive nozzle, to which a mixing chamber adjoins in the flow direction of the primary circuit. This mixing chamber has in comparison to the drive nozzle for the driving medium on a larger flow area, so that the driving medium from the drive nozzle enters the mixing chamber in the form of a free jet. The motive nozzle is preferably in the form of a convergent nozzle. However, other nozzle shapes are also realizable, in particular as a function of the fluid or the physical state of the fluid.

Upon the entry of the propellant into the mixing chamber, the suction medium is entrained from the secondary circuit, for example, due to a resulting shear stress. As a result, it is accelerated, so that a negative pressure is created in the mixing chamber, through which the suction medium is conveyed or sucked out of the secondary circuit. To further improve the suction, the mixing chamber may be followed by a diffuser in the flow direction of the primary circuit.

In the described embodiment of the fluid circuit, the number of necessary switching valves can be reduced, because in a preferred embodiment between the first branch and the second branch no switching valve for interrupting the flow connection through the primary circuit is necessary. Rather, the fluid flowing from the first branch to the second branch serves to convey the fluid from the secondary circuit by passing through the jet pump. Also, the occurrence of the abrupt increase in temperature is prevented because subsequent to the confluence of the secondary circuit in the primary circuit, for example, at the second branch, not only fluid from the secondary circuit is present. Rather, in addition to the conveying of the fluid from the secondary circuit necessary fluid of the primary circuit, which is also mixed in the jet pump with the former. Because during discharge of the heat accumulator, the temperature of the fluid of the secondary circuit is usually much higher than the temperature of the fluid of the primary circuit, this mixing brings the temperature to a mixing temperature which is between the two temperatures and the mixing ratio between the fluid of the primary circuit and the fluid of the secondary circuit is determined.

A further embodiment of the invention provides that the secondary circuit opens into the primary circuit at a first branch and at a second branch arranged downstream of the first branch, the two branches being present in the primary circuit upstream of the heat consumer. As already explained above, there are two branches, via which the two circuits are flow-connected to one another. Both in the primary circuit and in the secondary circuit, there is a flow direction from the first branch to the second branch. The two branches are thus flow-connected to one another via the primary circuit as well as via the secondary circuit.

In a first operating mode, only a flow connection via the primary circuit is present between the first branch and the second branch. In contrast, in the second operating mode, the secondary circuit is also released, so that the fluid can flow or flow from the first branch to the second branch both through the primary circuit and through the secondary circuit. In the second mode, depending on the temperatures of the fluid in the primary circuit and the secondary circuit, either loading or unloading of the heat accumulator may be provided.

The heat consumer is provided downstream of the two branches. This means that when unloading the heat storage, the fluid removed from this can enter directly into the heat consumer. In that regard, a high efficiency of the fluid circuit is ensured.

A development of the invention provides that the jet pump is provided at the second branch. The jet pump thus operates as a suction jet pump, wherein the fluid flowing in the primary circuit serves as the driving medium and the present in the secondary circuit or the heat storage fluid is sucked by the vacuum formed in the jet pump and can be referred to as suction medium. For loading or unloading the heat accumulator, the flow connection through the secondary circuit is released, so that the fluid flowing in the primary circuit is split at the first branch into a first fluid flow and a second fluid flow. The first fluid stream flows through the primary circuit in the direction of the second branch and serves there as a propellant of the jet pump. By contrast, the second fluid flow is conveyed by means of the jet pump, in particular starting from the first branch, through the secondary circuit or the heat accumulator.

A particularly preferred embodiment of the invention provides that a motive nozzle of the jet pump is connected to the primary circuit or forms a part of this. The function of the motive nozzle has already been discussed above. The motive nozzle should be fluidly connected to the primary circuit, so that it is flowed through by the fluid present in the primary circuit when the fluid pump is operated to convey the fluid or the fluid is circulated in the primary circuit. Alternatively, the motive nozzle can of course be present as part of the primary circuit, so that the motive nozzle or the jet pump is not present as a separate element, but is integrated into a line of the primary circuit.

A further embodiment of the invention provides that the secondary circuit is connected to a suction port of the jet pump. This suction connection is in direct flow connection to the mixing chamber, so that the negative pressure formed in the mixing chamber also bears directly on the suction connection. Via the suction connection, therefore, the fluid is conveyed from the secondary circuit into the jet pump and mixed there with the fluid of the primary circuit.

In a preferred embodiment of the invention it is provided that the switching valve in the secondary circuit is arranged downstream of the heat accumulator. As already mentioned, the at least one switching valve is provided in the secondary circuit. By means of the switching valve, the flow connection through the secondary circuit can either be enabled or interrupted. In order to prevent that fluid is conveyed from the heat accumulator through the jet pump despite interrupted flow connection, the switching valve is downstream of the heat accumulator and thus fluidly provided between this and the jet pump.

In at least one embodiment of the invention, a further switching valve may be provided in the secondary circuit downstream of the heat accumulator. The further switching valve thus serves to interrupt or release a flow connection between the first branch and the heat accumulator. With its help, it is therefore possible, for example, to prevent fluid from being forced out of the primary circuit into the heat accumulator during operation of the fluid pump despite the switching valve being closed. In a particularly preferred embodiment, therefore, a plurality of switching valves are provided, wherein one of the switching valves downstream of the heat accumulator and the other of the switching valves upstream of the heat accumulator is arranged fluidically.

A development of the invention provides that the fluid pump is arranged in the primary circuit upstream of the first branch. The fluid pump serves to circulate the fluid in the primary circuit. In such an arrangement, the fluid pump can act on both the first branch and arranged on the second branch jet pump with delivery pressure. In a likewise feasible arrangement of the fluid pump fluidly between the first branch and the second branch, although the second branch and thus the jet pump would be subjected to the delivery pressure, but at the same time fluid would be sucked from the direction of the first branch. This could result in fluid being sucked out of the secondary circuit via the first branch into the primary circuit in the event of a released secondary circuit and inadequate delivery rate of the jet pump, contrary to the flow direction actually provided. Although an arrangement of the fluid pump downstream of both the first and the second branch avoids this as well as the particularly preferred arrangement described above, but due to pressure losses, in particular of the heat consumer, has a lower efficiency than these.

A further embodiment of the invention provides that the heat accumulator is a fluid tank for a fluid used in the fluid circuit or a latent heat accumulator. The fluid tank can thus serve to temporarily store the fluid from the primary circuit. When loading the heat accumulator, for example, warm fluid is removed from the primary circuit and introduced into the heat accumulator so that it is filled with the warm fluid. In a discharge, however, fluid is removed from the heat storage and fed back to the primary circuit. It can be provided that the heat storage fluid is always supplied as it is removed.

Alternatively, it can also be provided to supply the heat storage during loading at least temporarily only fluid without removing fluid. Similarly, it may be provided during unloading, at least temporarily remove only fluid without supplying fluid. In such an embodiment, pressure compensation means are preferably provided to compensate for the differences in pressure caused by different levels of the heat accumulator. The heat accumulator may for example also be designed as a stratified charge storage in which the fluid is present in a temperature-layered manner. Another possibility is to form the heat storage as latent heat storage in which a latent heat storage medium is present, which can either remove heat from the heat storage fluid supplied or this heat.

Finally, it can be provided that the fluid circuit is designed as a cooling circuit or lubricant circuit of an internal combustion engine. It has already been explained in the introduction that the fluid circuit can in principle be designed as desired. However, it is particularly preferred that it serves to control the temperature of a coolant of an internal combustion engine of the motor vehicle and so far exists as a cooling circuit. Alternatively, it can also be used for tempering lubricant, so that it is designed as a lubricant circuit.

The invention will be explained in more detail with reference to the embodiments illustrated in the drawings, without any limitation. The single figure shows a schematic representation of a fluid circuit of a motor vehicle, which has a primary circuit and a secondary circuit.

The figure shows a fluid circuit 1 a motor vehicle, not shown, which is designed for example as a cooling circuit. The fluid circuit 1 has a primary circuit 2 on, which is reproduced here only in a greatly simplified form. The primary circuit 2 has a fluid pump 3 and a heat consumer 4 , In addition, the primary circuit 2 a heat source only indicated here 5 be assigned, which for example, in the form of a drive device, in particular a cooling jacket of the drive device is present. The heat source 5 provides at least temporary heat, which by means of a in the primary circuit 2 provided or circulating fluid in the direction of the heat consumer 4 can be transported. The heat consumer 4 is for example in the form of a passenger compartment heating of the motor vehicle. For example, both the heat consumer 4 as well as the heat source 5 designed as a heat exchanger.

In periods where the heat source 5 Heat supplies, the heat consumer 4 However, this is not needed to caching heat is a secondary circuit 6 intended. Using the secondary circuit 6 or a heat storage associated therewith 7 Heat can be cached. This heat can be used in periods of time in which the heat source 5 no or too little heat supplies, the heat consumer 4 However, heat is needed, the secondary circuit 6 or the heat storage 7 taken and the heat consumer 4 be supplied. For this purpose, the secondary circuit 6 or the heat storage 7 parallel to the primary circuit 2 connected. That means he's at a first turnoff 8th from the primary circuit 2 branches off and at a second branch 9 rejoins him again. The first branch 8th and the second branch 9 are therefore both about the primary circuit 2 or a line 10 of the primary circuit 2 as well as over the secondary circuit 6 or a line 11 of the secondary circuit 6 in terms of flow.

In the secondary circuit 6 or the line 11 is also a switching valve 12 provided, which downstream of the heat accumulator 7 , So fluidly between this and the second branch 9 is arranged. In addition, another switching valve 13 upstream of the heat accumulator 7 , So fluidly between the first branch 8th and this present. Using the switching valves 12 and 13 can each have a flow connection through the secondary circuit 6 or the line 11 released in a first switching position and interrupted in a second switching position.

A fluidic connection between the primary circuit 2 and the secondary circuit 6 is in particular via a jet pump 14 produced. This is at the second branch 9 intended. That means a motive nozzle 15 the jet pump 14 to the primary circuit 2 namely to the line 10 connected. The secondary circuit 6 or the line 11 is on the other hand to a suction connection 16 the jet pump 14 connected, which in direct flow communication with a mixing chamber 17 the jet pump 14 stands. The motive nozzle 15 is in the direction of flow of the primary circuit 2 designed as a convergent nozzle, so that at an opening point of the motive nozzle 15 into the mixing chamber 17 a cross-sectional enlargement is present.

Will now use the fluid pump 3 Fluid through the primary circuit 2 or the line 10 promoted, so arises in the mixing chamber 17 and at the suction port 16 a negative pressure. Is the flow connection through the secondary circuit 6 using the switching valves 12 and 13 released, this negative pressure causes fluid from the heat storage 7 from the jet pump 14 is sucked. This sucked fluid is with the through the line 10 provided fluid mixed and in the form of the mixture the heat consumer 4 fed. This is for this purpose downstream of the jet pump 14 in front.

Using such a fluid circuit 1 may preferably the flow connection between the first branch 8th and the second branch 9 , hence the line 10 , valve-free, in particular check valve-free, be configured. It is therefore not necessary to provide a switching valve or a check valve at this point. Also is for the secondary circuit 6 no separate pump necessary. Another advantage of the presented fluid circuit 1 results from the fact that for conveying the fluid from the heat storage 7 the jet pump 14 Fluid from the primary circuit 2 is supplied, which usually has a lower temperature than that in the heat storage 7 stored fluid. In that regard, when unloading the heat storage 7 , So a removal of the fluid, no sudden increase in temperature in the range of the heat consumer 4 occur because always the cooler fluid from the primary circuit 2 with the fluid from the heat storage 7 is mixed.

LIST OF REFERENCE NUMBERS

1

Fluid circuit

2

Primary circuit

3

fluid pump

4

heat consumer

5

heat source

6

Secondary circuit

7

heat storage

8th

1. branch

9

2nd branch

10

management

11

management

12

switching valve

13

switching valve

14

jet pump

15

propelling nozzle

16

suction

17

mixing chamber

Claims (10)

Fluid circuit ( 1 ) of a motor vehicle, with a fluid pump ( 3 ) and a heat consumer ( 4 ) having primary circuit ( 2 ) as well as with a secondary circuit ( 6 ), a heat storage ( 7 ) and the primary circuit ( 2 ) is connected in parallel in terms of flow, the secondary circuit ( 6 ) at least one switching valve ( 12 ), which in a first switching position a flow connection through the secondary circuit ( 6 ) releases and interrupts in a second switching position, characterized in that the secondary circuit ( 6 ) via a jet pump ( 14 ) fluidically to the primary circuit ( 2 ) connected. Fluid circuit according to claim 1, characterized in that the secondary circuit ( 6 ) at a first branch ( 8th ) and at a downstream of the first branch ( 8th ) arranged second branch ( 9 ) in the primary circuit ( 2 ), the two branches ( 8th . 9 ) in the primary circuit ( 2 ) upstream of the heat consumer ( 4 ) are present. Fluid circuit according to one of the preceding claims, characterized in that the jet pump ( 14 ) at the second branch ( 9 ) is provided. Fluid circuit according to one of the preceding claims, characterized in that a motive nozzle ( 15 ) of the jet pump ( 14 ) to the primary circuit ( 2 ) or forms part of this. Fluid circuit according to one of the preceding claims, characterized in that the secondary circuit ( 6 ) to a suction port ( 16 ) of the jet pump ( 14 ) connected. Fluid circuit according to one of the preceding claims, characterized in that the switching valve ( 12 ) in the secondary circuit ( 6 ) downstream of the heat accumulator ( 7 ) is arranged. Fluid circuit according to one of the preceding claims, characterized in that a further switching valve ( 13 ) in the secondary circuit ( 6 ) upstream of the heat accumulator ( 7 ) is provided. Fluid circuit according to one of the preceding claims, characterized in that the fluid pump ( 3 ) in the primary circuit ( 2 ) upstream of the first branch ( 8th ) is arranged. Fluid circuit according to one of the preceding claims, characterized in that the heat accumulator ( 7 ) a fluid tank for a in the fluid circuit ( 1 ) used fluid or a latent heat storage is. Fluid circuit according to one of the preceding claims, characterized in that it is designed as a cooling circuit or lubricant circuit of an internal combustion engine.

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