| 摘要 |
<p>1511639 Temperature control S OKUHARA 9 Sept 1976 [12 Sept 1975 3 March 1976] 37416/76 Heading G3R A motor or motors for opening and closing of a ventilation window or windows of a greenhouse are controlled in dependence on the greenhouse interior temperature. In general, there will be a motor for each window, but operation of a plurality of windows by a single motor is not precluded. In Fig. 1, each of the motors M1 to Mn is controlled by a corresponding unit B1 to Bn, in response to three inputs representing respectively the greenhouse temperature at 2, a reference temperature pre-set in respective units A1 to An and a signal derived from respective potentiometers P1 to Pn whose setting is varied either by the windows Gl to Gn or by the shafts of the associated motors M1 to Mn. These input signals are so combined as to cause the window opening to diminish as the temperature rises. The circuitry Figs. 2 to 5 (not shown), is such that the motors cannot be moved beyond the positions in which the windows are fully open or fully closed. If the temperature continues to fall once the windows are fully closed, a heating system 7 is switched on. If the external wind speed exceeds a selected "strong wind" value, the automatic control is over-ridden by units 5 and 6 which effect closure of all the windows. Provision is also made for a manually-operated override. The automatic control may be such as to provide a "dead" temperature zone within which the windows remain closed (or open) until a certain threshold value of temperature error has been exceeded. The temperature-sensing means 2 consists of a temperature-sensitive silicon diode connected in a bridge circuit.</p> |
