GB2127182A

GB2127182A - An arrangement for regulating the flow of heat transfer medium flowing through a heat exchange element

Info

Publication number: GB2127182A
Application number: GB08322211A
Authority: GB
Inventors: Albert Stolz; Wolfgang Biber
Original assignee: Daimler Benz AG
Current assignee: Daimler Benz AG
Priority date: 1982-08-20
Filing date: 1983-08-18
Publication date: 1984-04-04
Also published as: GB8322211D0; SE454577B; DE3231010C2; SE8304522L; SE8304522D0; GB2127182B; DE3231010A1

Abstract

A heat transfer medium, e.g. engine coolant, flows through the heating element 3, 4 of a heating and/or air conditioning system in a motor vehicle. A temperature responsive controlled timing valve 10 controls the flow in response to temperature sensors 12, 13, 14 and set point adjusters 15, 16. A throttle not operatively connected to the valve 10 is varied with the set- point adjusters 15, 16 in such a manner that, starting from a position II in which the set point temperature is easily reached, the throttle cross-section is continuously enlarged until the fully open position of the heating is reached. This makes it possible, particularly if the desired temperature is reached, and without reducing control accuracy, for the proportion of time during which the valve 10 is open to be still high even if there is only a slight flow of heat transfer medium because of the restriction of the throttle. Detrimental pressure surges and cold blowing are thus avoided. <IMAGE>

Description

SPECIFICATION An arrangement for regulating the flow of heat transfer medium flowing through a heat exchange element The invention relates to an arrangement for regulating the flow of heat transfer medium through a heat exchange element of a heating and/or air conditioning system in a motor vehicle, with the aid of a controlled timing valve having a shut-off element, and a throttle.

A controller of this type is known from German Offenlegungsschrift OS 29 26 320, the throttle in this case acting upon a chamber or space which lies above a valve seat and is separated therefrom by a diaphragm clamped on the edge side and which is connected to the outlet chamber via a valve core or insert which can be sealed on the upper side by a plunger, in the form of a needle of an electromagnet and which penetrates the valve disc received by the diaphragm and the valve seal. A hydraulically pilot-controlled valve, which opens particularly smoothly, is created as a result of these measures.

However, pressure peaks of brief duration also occur in the line system and in the heat exchanger during the valve closing operation since it is necessary to restrict a flow of heat transfer medium, which is at a constant level over the entire range of temperature selection, when the heat output required is less than the maximum available.

These pressure peaks accumulate if the set temperature level is reached, the duration of opening time of the valve still amounting to only an infinitely small porportion of total time so that, during the closing times particularly when there is a high rate of air flow through the heat exchanger, it can result in cold blowing which is felt to be unpleasant.

The object of the invention is to ensure by means of simple measures that, particularly if the desired temperature is reached and without reducing control accuracy, the duration of opening time of the valve is always high in relation to the total time even if there is only a slight flow of heat transfer medium, and that detrimental pressure surges do not occur when this flow is moderated.

According to the present invention there is provided an arrangement for regulating the flow of heat transfer medium through a heat exchange element of a heating and/or air conditioning system in a motor vehicle, including a controllable timing valve having a shut-off element for stopping said flow through the heat exchange element, and a throttle for restricting said flow which is operatively independent of the shut-off element, the cross-section of the throttle being selectively variable by a set-point adjuster wherein, from a starting position in which the throttle cross section is not fully closed, the throttle cross-section is continuously enlargable until a fully open position corresponding to a maximum flow of heat exchange medium through the throttle is reached.

Comfortable temperatures are achieved in an appropriate time, even in the event of low outside temperatures, if the throttle is at least half open when the set-point adjuster is in the central position, which corresponds to an interior temperature of approximately 23"C.

A simple and cheap construction for a right/left or separate control system at the front/rear for controlling the intake air and interior temperatures is obtained if at least two throttles are associated with a single timing valve.

A preferred embodiment of the invention will now be described by way of example with reference to the accompanying drawing which shows schematic layout of an arrangement for regulating the flow of heat transfer medium through a heat exchange element in a motor vehicle.

A line 2 leads off the water jacket of an internal combustion engine 1 (not shown in detail) having a water pump and opens into a heat exchange element 5 having two zones 3 and 4 which could also be spatially separated from one another and consequently form separate heat exchange clements. Lines 6, and 7 lead off the zones 3 and 4 and open into a collecting line 8 which is connected again to the water jacket of the internal combustion engine 1 to close the circuit. The heat from the water is used in the element 5 to heat air to be supplied to the interior of the vehicle.

A shut-off element 8 (not shown in detail) of an electromagnetically operated timing valve 10 is fitted into the collecting line 8, the control commands for the valve 10 being derived from a controller 11 and being responsive to temperature sensors 12-14 and set-point adjusters 1 5 and 1 6 to supply different input quantities. The temperature sensor 1 2 detects the air exit temperature of the zone 3, whilst the temperature sensor 1 3 serves to detect the air exit temperature of the zone 4.

The vehicle interior temperature is detected by the temperature sensor 14. Different temperatures can be preselected for the left and righthand passenger spaces by means of the setpoint adjusters 1 5 and 16, the rotation of an associated knob 1 7 or 1 8 causing the pivoting of an associated throttle 1 9 which is fitted in the line 6 and 7. The adjusting movement can be transmitted mechanically or with the aid of servo-controlled adjusting means.

The knobs 1 7 and 1 8 are shown in a position which serves to create the maximum heating capacity. The flap-shaped throttles 1 9 are each fully open and markings 20 on the knobs 1 7 and 1 8 indicate the position I of the scales or dials 21 and 22. If, for example, the knob 1 7 is now moved in an anticlockwise direction, the marking 20 moves to position II which corresponds to the 'cold' position and in which the associated throttle 1 9 is not fully closed. The throttle 1 9 can therefore be designed in the form of a butterfly valve which is relatively cheap to manufacture.

When set points are below the maximum value, there is consequently a slower flow of heating medium than at the highest set point so that the pressure peak which occurs in the system when the timing valve 10 is closed is also lower. As a result of the throttling action, the period over which the timing valve 10 is open in relation to the cycle time is increased simultaneously, whereby troublesome cold blowing is prevented during the now short closing times, particularly when heat outputs are low.

Thus, for set points lower than the maximum, by restricting the flow of the heating medium by means of the throttle 19, a relatively low degree of heat transfer takes place so that the valve 10 can remain open for a longer period of time, during which warm air is supplied, and shut for a relatively short time. This is in contrast to allowing an unrestricted rate of flow with a consequent high rate of heat transfer which would result in the valve 10 being shut for a longer period of time with the consequent risk of cold air being blown into the vehicle interior.

In the illustrated embodiment the set-point adjusters 1 5 and 1 6 can be set to different positions, despite using only one downstream timing valve 10, a different quantity of heating medium flows through the two zones 3, 4 during the opening time of this valve.

The fact that, on account of the throttle 1 9 not being fully closed in position 11, the associated zone 3 or 4 is easily heated up if the other set-point adjuster 1 5 or 1 6 is turned in the direction of position I is virtually of no importance since great temperature variations between the passenger spaces on the left and right-hand sides are in any case undesirable.

In order to prevent these temperature differences becoming too great, a total evaluation of the signals from the set-point adjusters 1 5 and 1 6 takes place. This means that the maximum possible stream of heating medium only flows if both set-point adjusters 1 5 and 1 6 are fully set at "hot", and that the timing valve 10 is closed while both set-point adjusters 1 5 and 1 6 are fully set at "cold'.

In order that a comfortable inside temperature may be achieved within an appropriate time when set points are below the maximum value itself and when outside temperatures are extremely low, the adjusting movement of the set-point adjusters 1 5 and 1 6 is transmitted to the throttles 19, within the temperature range of approximately 1 6"C to approximately 30"C, in such a manner that at least half the maximum possible stream of heating medium flows. In the case of suitable motor vehicle heat exchangers, already 80% of the maximum heating capacity is achieved thereby, but the pressure peak which is determined by the square of the heating medium flow rate is considerably moderated.

Claims

1. An arrangement for regulating the flow of heat transfer medium through a heat exchange element of a heating and/or air conditioning system in a motor vehicle, including a controllable timing valve having a shut-off element for stopping said flow through the heat exchange element, and a throttle for restricting said flow which is operatively independent of the shut-off element, the crosssection of the throttle being selectively variable by a set-point adjuster wherein, from a starting position in which the throttle crosssection is not fully closed, the throttle crosssection is continuously enlargable until a fully open position corresponding to a maximum flow of heat exchange medium through the throttle is reached.

2. An arrangement according to Claim 1, wherein the throttle is at least half open when the set point adjuster is in a central position, which is, in operation, equivalent to a vehicle interior temperature of approximately 23"C.

3. An arrangement according to Claim 1 or 2, wherein at least two throttles are associated with a single timing valve.

4. An arrangement for regulating the flow of heat transfer medium through a heat exchange element of a heating and/or air conditioning system in a motor vehicle, substantially as described herein with reference to and as illustrated in the accompanying drawings.