Abstract:
A valve arrangement for a hydraulic control apparatus, in particular a hydrostatic steering device, has a priority valve (1). From the priority outlet (CF) thereof a load pressure sensing line (19) extends to a load-pressure sensing point in the control apparatus (3). A pressure control valve (18) which holds the pressure arising at it constant is inserted in the load pressure sensing line (19). In this manner, with the customary priority valve largely being maintained, the stand-by pressure of this priority valve is increased.
Abstract:
A priority valve (1) for a hydraulic control apparatus (3), in particular a hydrostatic steering device, has a slide (10), a first pressure chamber (11) arranged at one end of the slide and connected by way of a first throttle (14) to a priority outlet (CF), and a second pressure chamber (12) arranged at the other end of the slide and having a spring (13). This second pressure chamber is connected by way of a series connection of first throttle (14), first pressure chamber (11) and second throttle (15) to the outlet (CF) and by way of a third throttle (13) to the load pressure connection (LS). In this manner the first pressure chamber (11) has liquid under pressure flowing continuously through it, with the result that operation is improved.
Abstract:
A hydraulic machine (1) is disclosed, having a gearwheel (4), which is arranged on a shaft (2) so that they rotate together and which has a first external toothing (5), a gear ring (7), which has a second external toothing (8) and a first internal toothing (6) which engages with the first external toothing (5), a toothed rim (10), which has a second internal toothing (9) that engages with the second external toothing (8), and having a commutation arrangement for supplying and discharging in the correct order hydraulic fluid in pressure pockets which are formed in the first and/or second toothed coupling in each case between external and internal toothing. It is desirable to be able to improve the operational behaviour of such a machine. For that purpose, on both axial sides of gearwheel (4) and gear ring (7) there is a respective lateral plate (34, 37), which plates are joined axially to one another and move jointly with the gearwheel (4) or the gear ring (7).
Abstract:
An adjustment device (1) for a radiator thermostat is disclosed, having a housing (17, 18, 2) in which a temperature sensor (6) is arranged. In such an adjustment device it is desirable to improve the thermal behaviour. For that purpose the housing (17, 18) is closed at its exterior.
Abstract:
A valve arrangement (9) for hydraulic work motors, especially for steering devices, that are operated by a control device, has an inlet (14) to be connected to a motor line, an outlet (18) to be connected to a tank line and a valve (10, 11) between the inlet and the outlet. The valve (10, 11) is controlled in dependence on the rate of rise of the input pressure and opens when the rate of rise exceeds a predetermined value. In that manner, undesirable acceleration of the work motor can be prevented.
Abstract:
In a stop valve (1) in which the maximum percentage opening is adjustable, the restriction of the valve is carried out by adjustment of a valve rod (3), on which a valve disc (4) is fixed, which cooperates with a valve seat (5) within the valve body (2) of the stop valve. The valve rod (3) consists of two axially movable parts (6, 7) which are adjustable in relation to each other by means of a driver connection, the most inner part (7) supporting the valve disc (4). In order to facilitate the adjustment and simplify the design the axially extreme valve rod part (6) is cylindric and has external threads (8), which cooperate with threads which are fixed in relation to the valve body. When said valve rod part (6) is rotated it moves in axial direction to or away from said valve seat (5). The axially inner valve rod part (7) is inserted in the cylindric extreme valve rod part (6) and the driver connection consists of a friction arrested screw connection (9) connecting the two valve rod parts.
Abstract:
The present invention relates to an ultrasonic flowmeter for measuring flows of liquid or gas through a measuring tube which is equipped with ultrasonic transducers, where the ultrasound is reflected by the tube wall, by focussing reflecting plane. If at least one focussing reflecting plane is ellipsoid, and the transducers are placed in the focal points of the ellipse, a simple and cheap ultrasonic flowmeter can be provided, which can carry out accurate and quick measurings.
Abstract:
The present invention relates to the measuring of phase currents in an inverter, where by pulse width modulation controlled semiconductor switches invert a direct voltage from an intermediate circuit into a three-phase alternating voltage. The phase currents are measured by measuring the intermediate circuit current when an active switch state creates an unambiguous relation between the intermediate circuit current and a phase current. Time shifts in the phase current measuring can be avoided by measuring the value id of the intermediate circuit current in two separate settings ( u 1, u 1; u 6, u 6) of the same active switch state ( u 1; u 6) in a modulation period (TSW) and by creating a resulting mean value of the measured values. The mean values can be related in time to the centre of the modulation period, and the third phase current at the same time can be calculated, because the sum of the phase currents is equal to zero.
Abstract:
A diaphragm-controlled differential-pressure valve has a valve housing (1) which is constructed in one piece with the lower part (5) of a diaphragm capsule (6). The associated cover (9) carries a spring housing (20) accommodating the set-point spring (18). This produces a valve having a very small overall height.
Abstract:
A method for defrosting a refrigeration system (38) makes provison for partial defrosting of the cooling surface (39) to be carried out at relatively short intervals, and for full defrosting to be carried out at longer intervals. To that end an associated control unit (41) has four timers (44 to 47) which determine the switching on and switching off times of the defrosting processes. In this manner the interval between successive full defrostings can be considerably increased.