FI60075B - ANORDNING VID EN TEMPERATURSKILLNADS- ELLER VAERMEMAENGDSMAETARE INNEHAOLLANDE AOTMINSTONE TVAO TEMPERATURBEROENDE MOTSTAOND - Google Patents

Description

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Jp »C (45) ^ '11 J 1 ^ ^ ^ (51) Kv.ik.3 / int.a.3 G 01 K 17/18 FINLAND — FINLAND (*) Patent application — PatentanaOknlnj 3639/73 (22) Hakemliptlvi - Anaeknlngadag 26.11.73 (13) AlkupUvi — Glltlfhetsdag 26.11.73 (41) Become Public - Bllvlt offentllg 09.06.7b

Patent and registration authorities ...., ,, ,,,. , _ ^, (44) Date of publication and date of publication. -

Patent and registration authorities AnsOkan uthgd och uthskriftM publkerad 31.07.8l (32) (33) (31) Pyydetty etuoikeus-Begird prloritet 08.12.72

Sweden-Sverige (SE) 16037/72 (71) AB Svensk Värmemätning C.B-System, Stälträdsvägen 33, S-lll 31 Bromma,

Sweden s-Sverige (SE) (72) Stig Ingvar Karlsson, Karlskrona, Sweden-Sverige (SE) (7 ^) Oy Kolster Ab (5U) Arrangement in a temperature difference or heat meter with at least two temperature-dependent resistors - Anordning vid en The present invention relates to an arrangement for reducing the load time in temperature difference and heat quantity measuring devices and, more specifically, to an apparatus for carrying out the procedure described in the Swedish hearing. 368 280.

According to this procedure, the load time in the heat measuring device is reduced so that a current (measuring current) which is pulsed is passed through the temperature-dependent resistor in the device. However, one drawback of the embodiment of this publication in the apparatus for performing this interrogation procedure is that it must be connected to an external mains voltage, which to a certain extent limits its range of use to installation locations where mains voltage is available.

The object of the present invention is to provide an arrangement for carrying out the procedure described in the above-mentioned publication, by means of which it is possible to connect it to a mains-independent source of supply voltage, e.g. a battery.

2,60075

The invention, the features of which will become more apparent from the appended claim, will be described in more detail with reference to the accompanying drawings, in which: Fig. 1 shows an embodiment of an apparatus according to the present invention, Fig. 2 shows a block diagram of a heat meter according to the present invention. invention means *

Figure 1 shows a schematic diagram of an embodiment of an apparatus for implementing a procedure according to the above publication. Reference numeral K denotes units in the dashed area, and this unit K corresponds to the pulse generating circuit K, which is also shown in the figure of the above-mentioned publication. By the designation So, as in the above-mentioned patent, I mean the contact part included according to the same drawing of the destination P. According to the present invention, the pulse shaping circuit K is rearranged so that a battery or a similar DC voltage source can be connected to it, as will be shown in more detail in Fig. 2. The pulse generating circuit K contains two different monostable alternators MV1 and Μν2, respectively. in parts (so-called CMOS type) * A time delay column R1, C1 and R2, C2, respectively, are connected to each alternator in a manner known per se, whereby resistors R1 and R2 are connected to the positive terminal of the battery. The trigger input to the alternator MV1 is connected to the output from the contact portion Ke so as to provide a trigger signal when a certain amount of fluid has been measured in the flow meter P, as described in the above-mentioned publication. Each alternator has an inverting and non-inverting output Q1, Q2 and Q1 and Q2, respectively. In the present embodiment, the output Q2 of the second alternator MV2 is connected to the second input of the gate G, as shown in Fig. 2, so that a pulse corresponding to the opening pulse shown in the above-mentioned leg is provided. The inverting output from the alternator MV1 is connected to the trigger input from the alternator MV2, whereby this alternator is triggered when returning to the zero state in the pulse present at the output Q1 when the alternator MV1 is triggered. As can be seen, the pulse times t1 and t2, respectively, can be varied by changing the time constants in the respective time slot circuits R1, C1 and R2, C2, respectively.

The inverting outputs of both alternators MV1 and MV2 are each connected to their ram input from the pulse shaping circuit PP. This includes transistors T1 and T2 with their respective base resistors R3 And R4 · Each emitter! these transistors are connected to the positive terminal of the battery in the case that the transistors are of the PNP type as in Fig. 1. A collector of transistor T1 is connected via resistor F5 to a cover 6006 of a third transistor T3 of NPN type The co-connection point forms the output of the pulse generating circuit. A pulse transformer Tr having an implementation similar to that of the above-mentioned patent transformer Tr in Fig. 3 is connected in its primary winding to the output of the pulse generating circuit and to the ground voltage. As in the embodiment according to the above-mentioned patent, this transformer has two secondary windings L1 and L2 connected to temperature-dependent resistors.

When flashing MV1 is fired from the contact part Ko, the outputs Q1 and Q1 are activated so that a pulse is generated over both of them according to the figure. At the end of the inverted pulse, the alternator MV2 is also triggered, so that pulses are generated at the outputs Q2 and Q2 according to Fig. 1. When a pulse P1 of length t1 occurs at the input to the pulse generating circuit PF, the transistor T1 is conducted after being blocked (as is the transistor T3) and the output P becomes negative (voltage equal to the negative voltage of the battery). This situation takes about a teaspoon. When the pulse P1 stops, the pulse P2 enters the output Q2 in the alternator MV2 and the transistor T1 is blocked in the same way as the transistor T3 · However, the transistor T2 will conduct current, whereby the output of the pulse generating circuit now switches to the positive voltage of the battery. Thus, two successive pulses of opposite polarity are provided at said output, which will be referred to below as a pre-pulse and a measuring pulse, respectively, whereby the measuring pulse starts at the same time as the opening pulse for the gate G present at the output Q2. Thus, a pre-pulse of different polarity compared to the measuring pulse is obtained via the transformer and the temperature-dependent resistors are thus pre-magnetized by this pre-pulse of the transformer Tr. Thus, a value of zero is obtained as the average of the magnetizing current, and the output pulses from the transformer Tr are, on average, independent of the magnetizing current. Thus, no current consumption occurs in the transformer between measurement times, which makes the procedure suitable for battery operation. The pre-pulse can be selected so that the time integral of its voltage is equal to that of the measuring pulse, for example the same amount of voltage ptiolet so long.

Figure 2 shows the connection of the battery to the pulse generating circuit K and the differential circuit D, from the analog to digital transformer AD and to the flow meter P. The same reference numerals as those used in the above-mentioned patent have also been used in this case. Battery B is thus used as a bias voltage source for these units as unit SD was used in the embodiment according to that patent (compare Figure 1 in this case). In addition, in the present embodiment, the contact part Ke has a

Claims (1)

4,60075 sa P connected to the battery B. The contact part Ke can thus be realized as a transistor line, which is controlled to conduct via the determiner P. By using monostable alternators as an integrated embodiment as described above, the pulse generating circuit K can be implemented, enabling a quiescent current which is practically zero (of the order of nA). The differential circuit D, the analog-to-digital converter AD and the port G are already provided in the embodiment according to the above-mentioned patent so that they have no quiescent current. Using a period divider of the electronic calculator E, which is of the integrated CMOS type, a quiescent current of the order of nA is obtained for the entire measuring equipment. Claim: Apparatus in a temperature difference or heat meter comprising at least two temperature-dependent resistors arranged to sense the temperature in a fluid flowing at at least two points, a separation circuit indicating a difference current forming a measure of the temperature difference in that fluid, converting it from analog to digital differential current pulses having a period proportional to the difference current, a gate whose first input is connected to the output of the transformer and the second input is connected to the output of a pulse generating circuit controlled by a counter 11a, characterized in that the pulse generating circuit (K) connected to the output of a meter (P), a second monostable alternator (MV2) whose trigger input is connected to the second output of the previously mentioned monostable alternator (MV1) and which the second output is connected to the second input from the above-mentioned port (G) and as a pulse shaping circuit (PF) with two inputs and outputs, each of these inputs being connected to the same output of said alternators so that its output produces two consecutive poles of opposite polarity the pulses being arranged to be supplied to a primary winding in a transformer (Tr) comprising two secondary windings connected to the above-mentioned temperature-dependent resistors, each alternator having its own time delay circuit (R1, C1 and R2, C2, respectively) and the above-mentioned pulse shaping circuit (P? ) connected to a constant bias voltage.