4results about How to "Eliminate backflow" patented technology

The invention relates to the technical field of mine refrigeration and cooling, in particular to a mine refrigeration and cooling pipeline arrangement system. The water outlet end of a main circulation pipeline is connected with the water inlet end of a cooling device to form a closed circulation loop; the main circulation pipeline is laid in the extending direction of the roadway and serves as a liquid supply mother pipe of each refrigerating unit. The branch pipelines of the refrigerating units are respectively led out from different positions on the main circulation pipeline; the negative pressure water return devices are installed on the main circulation pipeline in series, and each negative pressure water return device is located behind the branch pipeline leading-out point of the refrigerating unit corresponding to the negative pressure water return device and in front of the branch pipeline leading-out point of the next refrigerating unit and used for forming an alternate series-connection arrangement structure. Through alternate series arrangement, the dual functions of liquid supply and water return of the main circulation pipeline are achieved, the pipeline layout is greatly simplified, the roadway space occupation is reduced, the installation cost and the leakage risk are reduced, and the system adapts to complex working conditions of mines.

This invention discloses a method for preventing backflow impact in high-altitude simulation tests of solid rocket motors. A bidirectional sealing gate valve is installed between the diffuser and the ejector pipe. At the start of the test, after the ejector system is activated, the gate valve opens, the engine ignites, maintaining a low pressure of 1 kPa within the test chamber and allowing exhaust gases to escape, forming a stable flow field. The gate valve closes at the end of ignition, and nitrogen is injected into the test chamber in stages to restore atmospheric pressure, preventing sudden pressure changes that could damage the engine structure. This invention, through the bidirectional sealing gate valve structure and the nitrogen staged replenishment system, utilizes the sealing and isolation characteristics of the gate valve to solve the backflow impact problem in high-altitude simulation tests of solid rocket motors, maintaining a constant low-pressure environment in the test chamber, completely eliminating exhaust gas backflow, protecting the structural integrity of the engine after the test, and improving the test success rate.

The application relates to the technical field of fire pumps, and provides a pressure-adjustable anti-backflow fire pump which comprises a pump body provided with a water inlet pipe and a water outlet pipe, the water outlet pipe is provided with an anti-backflow mechanism, the water inlet pipe is provided with a pressurizing mechanism, a transmission mechanism is arranged between the anti-backflow mechanism and the pressurizing mechanism, the anti-backflow mechanism at least comprises an anti-backflow pipe and an anti-backflow ring, the anti-backflow ring can move in the anti-backflow pipe, when the anti-backflow ring moves towards the pump body, the pressurizing mechanism can be driven by the transmission mechanism to pressurize the water inlet pipe, and the rotating speed of the impeller of the pump body can be adjusted according to the moving distance of the anti-backflow ring; the application can determine that the backflow phenomenon occurs in the pipeline by detecting the movement of the anti-backflow ring, and can be timely treated and maintained; and when the anti-backflow ring moves, the rotating speed of the impeller is adjusted to offset the force of the reverse water flow, so that the control is stable and convenient.

In order to overcome the technical problem of poor time sequence control precision in the prior art, the invention provides a circuit and a chip for generating a clock signal. The circuit for generating the clock signal comprises a first NAND gate device and a second NAND gate device which are in cross coupling, the first output end of the first NAND gate is connected with the fourth input end of the second NAND gate, the second output end of the second NAND gate is connected with the second input end of the first NAND gate, and a closed-loop cross coupling structure is formed. By means of the connection mode, output signals of the two NAND gates are mutually restricted and triggered, and a time sequence interlocking mechanism is achieved. Namely, when the first NAND gate outputs a high level, the signal is transmitted to the fourth input end of the second NAND gate, and the output of the second NAND gate is a low level. And vice versa. In this way, the overlapping problem that clock signals are low in level at the same time is completely eradicated structurally, and the non-overlapping time sequence precision of the clock signals is greatly improved.