68results about How to "Achieve linear adjustment" patented technology

The device includes a radio frequency input module, down-conversion module, first loop of analog-digital composite feedback, second loop of digital feedback, feed forward loop, and base band processing module. The device possesses functions of sampling signals under high ratio of S / N by A / D converter module, extending range of variable gain amplifier, keeping power constant of multicarrier signal from receiver to output to base band under large signal dynamic range so as to meet requirement for power of each multicarrier signal by base band, root mean square detection adopted in power detection module to carry out linearization correction for non linearity of gain.

The invention relates to the technical field of flow valves and provides a micro-flow regulating valve, which is high in regulating accuracy and centralized in flow area and comprises a sleeve valve seat and a valve core arranged in the sleeve valve seat. A boss is arranged in a water outlet of the sleeve valve seat, the valve core head is tightly matched with the boss, and a fluid passing through groove with an overflowing area gradually decreased along the water inlet direction is arranged on one side of a valve core head portion. Further, the fluid passing through groove is a triangular groove. The valve core enables the whole flow area to be centralized in the groove from an original annular area and enables a local area to be increased and not to be blocked by small sundries. The overflowing area of the fluid passing through groove is gradually decreased along the water inlet direction so that linear regulating can be achieved. By means of design of the triangular groove, flow regulating can be controlled accurately, processing is easy, the diameter of the valve core can be larger than that of an existing valve core, and processing strength can be ensured.

The invention relates to a high power linear output high voltage stabilizing device and a high power linear output high voltage stabilizing method. The device comprises a chord wave generating circuit, a sine wave amplitude amplifier circuit, a prime power amplifier circuit, a push-pull power amplifier circuit, a boosting transformer, a high voltage rectifier filter circuit, a high voltage direct current (DC) output interface, a current sampling circuit and a voltage sampling circuit which are sequentially connected, wherein the current sampling circuit and the voltage sampling circuit are respectively connected with a micro-programmed control unit (MCU) and an over-voltage and over-current protection circuit; the device also comprises a voltage and current display connected with the MCU. The invention provides the high power linear output high voltage stabilizing device and the high power linear output high voltage stabilizing method which are high in stability and accuracy rate and realize high-power output.

The present invention provides an auto electronic heating / ventilation air condition, including a generator, an electronic cooler / heater, a heat pipe, a water pump and a radiating tank. Kinetic energy generated by auto engine drives engine working, supplies electricity to auto electronic heating / ventilation air condition, and semiconductor refrigeration plate in the electronic cooler / heater cools or heats air in auto by circling water or antifreeze. This system need not refrigerant, has no pollution, small noise and lower efficiency, protects environment and saves energy.

The invention relates to a solenoid type electromagnetic trip, which belongs to the technical field of the low-voltage apparatus. The solenoid type electromagnetic trip comprises a knob, an adjusting rod, a spring, a moving iron core, a static iron core, a coil, a concentrating flux plate and a magnetic yoke and is characterized in that a push rod pivotally arranged at the upper end part of the magnetic yoke is also included, wherein, one end of the spring is connected with the adjusting rod, the other end of the spring is connected with the push rod, and the upper end of the moving iron core is movably connected with the push rod after penetrating the concentrating flux plate. The invention has the advantages that the linear regulation of the current setting value for the short circuit action is realized by adjusting the length of the spring through the knob; since the adjusting screw component is arranged on the magnetic yoke, the magnetic gap can be adjusted finely, the inconsistency of the current setting values of all the trips due to the parts and the assembly is eliminated, and the consistency of the initial states of all the trips is ensured; and at least one hanging hook is arranged on the upper edge of the push rod, so that the specification of the spring is reduced when the multi-gear adjustment is realized.

The invention discloses a module assembly of an intelligent electronic halt vehicle system, comprising an exhaust solenoid valve, an intake solenoid valve, a normally open solenoid valve, a normally closed solenoid valve, a halt vehicle relay valve and a pressure sensor which are all arranged on a central controller. Compared with the prior art, the module assembly of the intelligent electronic halt vehicle system disclosed by the invention realizes the regulation for a halt braking force through the exhaust solenoid valve, the intake solenoid valve, the normally open solenoid valve, the normally closed solenoid valve, the halt vehicle relay valve and the pressure sensor, and can also achieve the linear regulation for the halt braking force through a real-time feedback of a voltage signal from the pressure sensor. Due to the linear control function for the halt brake force, the module assembly of the intelligent electronic halt vehicle system can be used as an emergency brake when the braking force of a vehicle does not meet the braking demand. Compared with traditional pneumatic-controlled halt vehicle systems, the module assembly of the intelligent electronic halt vehicle system can avoid the sliding at the beginning of halting on a ramp and the delay at the beginning of starting a vehicle, and can shorten the braking distance in the case of an emergency braking.

The invention relates to a dynamic simulation experiment table for anti-lock braking systems based on magnetic powder clutch, while prior domestic enterprises has no production of automobile anti-lock braking system detection devices, and only sale the products of Japan, Canada and the like. Prior detection devices all adopt roller type and mount anti-lock braking systems on automobiles in test. The dynamic simulation experiment table comprises an energy transmission shaft (1) respectively connected with a flywheel (2), a torque sensor (3), a magnetic powder clutch (4) and a gear (5), and connected with wheels via a transmission flange (6), wherein the wheels are connected with a brake plate (7), and the energy transmission shaft (1) is connected with an iron table via a bearing (8) and abearing base (9). The dynamic simulation experiment table is applied in the performance detection of automobile anti-lock braking systems.

The invention discloses a valve-in-valve applied to the zero power of a turbine low pressure cylinder. The valve-in-valve comprises a first valve seat, a first valve element, a first driving component, a second valve seat, a second valve element and a second driving component. A first circulating hole is formed in the first valve seat, the first valve element is arranged on the first valve seat, and the first driving component is connected with the first valve element in a transmission mode and is used for driving the first valve element to move to make the first valve element open or close the first circulating hole. The second valve seat is arranged on the first valve element, a second circulating hole is formed in the second valve seat, the second valve element is arranged on the secondvalve seat, and the second driving component is connected with the second valve element in a transmission mode and used for driving the second valve element to make the second valve element to open or close the second circulating hole. The first circulating hole is used for carrying out linear mediation on circulation of maximum discharge, the second circulating hole is used for carrying out linear regulation on minimum discharge, and flexible switching of the maximum discharge and the minimum discharge is achieved through alternative opening of the first circulating hole and the second circulating hole.

An anti-blue-light resin lens made from a fluorescent masking agent is manufactured in the following steps of (1) monometer preparation, (2) pouring, solidification, demoulding and stabilization and (3) hardening and film coating according to percentage by weight. According to the anti-blue-light resin lens, the broadband fluorescent masking agent is added into a lens monometer according to a certain ratio and is evenly dispersed, as a result, 99 percent of ultraviolet light, with wave length ranging from 220 nanometers to 380 nanometers, harmful to the human body can be attenuated through absorption, part of purple light and blue light with wave length ranging from 400 nanometers to 480 nanometers is attenuated through absorption in a relatively linear mode at the same time, in this way, original anti-blue-light capacity of a lens is remarkably improved on the premise that high light transmittance of the lens is guaranteed, and the blue light attenuation rate is increased to over 40 percent from originally 10-20 percent after film coating, linear adjustment of blue light frequency attenuation is realized, and the anti-blue-light resin lens has the advantages of being advanced in technology, simple in process, high in practicability and capable of selectively adjusting the blue light frequency attenuation rate.

The invention discloses a copper processing cooling water pressure automatic control device, comprising a cooling water inlet pipe, a cooling water outlet pipe and a cooling water storage tank, wherein the cooling water inlet pipe is communicated with the cooling water storage tank, the cooling water storage tank is internally provided with a liquid level adjusting piston and a water storage inputpipe, the water storage input pipe is located above a joint between the cooling water inlet pipe and the cooling water storage tank, the liquid level adjusting piston is located below the joint between the cooling water inlet pipe and the cooling water storage tank, the bottom of the liquid level adjusting piston is connected to a piston driving connecting rod, and the bottom of the piston driving connecting rod extends out of the cooling water storage tank and is in transmission connection with a lifting drive mechanism. The copper processing cold water pressure automatic control device canrealize the linear correlation adjustment of cooling water pressure, thereby ensuring the accurate adjustment of cooling water pressure, improving the stability of production quality of an upward continuous casting machine. A water pressure regulation system has a simplified structure.

The invention relates to a spiral tube type adjustable electromagnetic release which comprises a rotary knob, an adjustable lever, a movable iron core, a static iron core, a support, a coil, a draw bar, a supporting frame and a base, wherein the coil is sheathed on a coil frame; the static iron core is arranged in a coil frame and is fixed with the support; the movable iron core is arranged above the static iron core; the upper end of the movable iron core is connected with the draw bar; the upper end of the base is fixedly provided with the supporting frame; the adjustable lever is arranged in the supporting frame by a revolute pair; the draw bar is arranged in the base by the revolute pair; a hanger is arranged at the lower side of the adjustable lever along the radial direction of the adjustable lever in a stretching way; a spring is connected between the hanger and the draw bar; a contact arm is arranged at the upper side of the adjustable lever; an adjustable surface with the variable radius is arranged on the outer wall of the rotary knob; and the adjustable surface is contacted with the end surface of the contact arm. The adjustable lever is contacted with the adjustable surface formed by Archimedes spiral curved surfaces on the rotary knob; when the rotary knob is rotated, the adjustable lever can be rotated; the rotation of the adjustable lever drives the upper end of the spring to move, thereby adjusting the length of the spring and realizing the linear adjustment of the setting value of short-circuit action currents.

The invention discloses an LED dimming circuit which comprises an adjusting control module and a voltage stabilizing module. The adjusting control module comprises a current detecting potentiometer which is connected with an LED loader and used for adjusting the brightness of the LED loader. The voltage stabilizing module comprises a voltage comparer U1 and a voltage stabilizing control chip U2, wherein the normal phase input end of the voltage comparer U1 is connected with the current detecting potentiometer, the output end of the voltage comparer U1 is connected with the voltage stabilizing control chip U2 to be used for feeding adjustment of the current detecting potentiometer back to the LED loader through the voltage stabilizing control chip U2, and the voltage stabilizing control chip U2 is used for adjusting and stabilizing voltage at the two ends of the LED loader according to the electrical level of the output end of the voltage comparer U1. The invention further discloses an LED lamp. The LED dimming circuit can stably adjust the brightness of the LED loader, meets various requirements of people, guarantees that a light source is stable and free of flickering when being adjusted, reduces energy loss caused by resistance heating and improves energy utilization rate.

The invention provides a graphene based passive depolarizer which is used to adjust the polarization degree of laser. The depolarizer is characterized by comprising a condensation unit and a polarization adjustment unit, the polarization adjustment unit is arranged in an optical path of the condensation unit, and separated from the condensation unit; and the polarization adjustment unit includes a garnet film in which graphene grows. The invention also provides a method for preparing the passive depolarizer. The method is characterized in that the garnet film in which graphene grows is prepared via a chemical vapor deposition method, and serves as the polarization adjustment unit. According to the passive depolarizer provided by the invention, the distance between the condensation unit and polarization adjustment unit is adjusted to adjust the polarization degree of laser linearly, the adjustment range is wide, and the adaptability is high; and according to the preparation method of the passive depolarizer, preparation can be completed via common materials and fewer steps, the cost is low and preparation is easy.

The invention discloses a self-adapting rotary electric air door control method for a refrigerator and relates to the technical field of refrigerator control. The self-adapting rotary electric air door control method comprises the following steps that firstly, when the refrigerator starts to refrigerate, the opening size of a rotary electric air door is 50% of the opening size in the fully openedstate; secondly, the cold chamber temperature T1 when the rotary electric air door of the refrigerator is opened and the cold chamber temperature T2 after a period of time t are detected and recorded,and the change amount delta T of the two temperatures is calculated, wherein delta T is equal to T1-T2; and thirdly, the delta T value is compared with the target value T, and the maximum opening size of the rotary electric air door is determined. According to the self-adapting rotary electric air door control method for the refrigerator, the maximum opening value of the rotary electric air dooris controlled by detecting the temperature variation of a cold chamber, so that the rotary electric air door can be installed in refrigerators with different capacity sections and meet the refrigeration requirements of the refrigerators with different capacity sections, and the standardization and generalization of the structural design of the refrigerator are improved; meanwhile, the cold air isreasonably distributed, the utilization rate of the cold air is increased, and thus the purpose of saving energy is achieved.

The invention relates to an adjustable constant current source integrated chip and a manufacturing method. The adjustable constant current source integrated chip comprises a monocrystalline silicon N-type polished wafer which serves as an N-doped region, an N+ heavily doped region is arranged on the back of the N-doped region, a triode Q2, a current regulative diode (CRD), a triode Q1 and a resistor R are arranged on the front of the N-doped region, one end of an N+ doped region of the resistor R is connected with an N+ doped region of the triode Q2, meanwhile, the N+ doped region of the resistor R serves as the cathode of the constant current source integrated chip, the other end of the N+ doped region of the resistor R is respectively connected with an N+ doped region of the triode Q1 and a P doped region of the triode Q2, a P doped region of the triode Q1 is respectively connected with a P doped region of the CRD, the P doped region of the triode Q2 and an N doped region of the triode Q2, an N doped region of the CRD is respectively connected with the P doped region and a second N+ doped region of the CRD, and the N+ heavily doped region serves as the anode of the constant current source integrated chip.

The invention discloses a current linear control circuit for a constant current source. the circuit comprises a triode Q1, a first field effect transistor U1, a second field effect transistor U2, an operational amplifier U3, a first resistor R1, a second resistor R2 and a third resistor R3. The output end of the operational amplifier is connected with the grids of the two field effect transistors, and then the sources of the two field effect transistors are connected with the second input end of the operational amplifier. In this way, a closed-loop negative feedback is formed. Through adjusting the voltage of a third network node and applying a high level on a first network node, a second network node is enabled to output a current of a certain value. In this way, the current linear adjustment of the current source is realized. The current value is convenient to adjust and stable in adjustment process, while the sudden rapid change of the circuit is avoided. Through arranging the above two field effect transistors, the current is prevented from getting too large to damage electrical devices. The circuit is high in safety, stable in performance, simple in design, low in cost and wide in application range, so that the circuit can be widely applied to simple constant current sources.

The invention discloses portable fault indicator detection equipment, belonging to detection equipment. The portable fault indicator detection equipment comprises a UPS power supply, an ammeter, a singlechip, a touch screen and an internal control circuit, wherein the internal control circuit comprises a transformer T1, a transformer T2, a switch NO1, a switch NO3, a mutual inductor Q, an induction coil L and a current regulating branch; the current regulating branch circuit comprises a switch NO2, a current measuring range switching switch S2, an adjustable resistor R1 and a resistor R2; theammeter is connected with the UPS power supply; the switch NO3 and the transformer T2 are connected in series between a tested fault indicator and a power supply output end of the UPS power supply; and the singlechip is connected with the touch screen. By the adoption of the portable fault indicator detection equipment, voltage and current waveforms of various faults can be simulated, a pluralityof faults and anti-misoperation functions can be tested; the UPS power supply is provided so that a fault indicator test can be carried out in a field environment with power supply or power failure; and circuit faults are simulated in a state sequence mode of voltage and current to test whether the fault indicator can work normally or not, the fault indicator is guaranteed to be in a reset state after the test is finished, and a network can be hung in time.

The invention provides a carpet yarn twister, and relates to the field of textile machinery. The carpet yarn twister comprises a rack, a yarn frame device, an electric spindle device, an overfeeding device and a winding device, in the electric spindle device, a hollow spindle rod is fixedly connected with a motor, the motor drives the hollow spindle rod to rotate, and a twisting disc and a yarn storage disc are fixedly connected with the hollow spindle rod, and rotate with the hollow spindle rod; the yarn storage disc is provided with a yarn discharge hole communicated with a yarn channel inside the hollow spindle rod; a spindle jar used for accommodating an internal yarn winding package is connected with the hollow spindle rod through a spindle rod bearing, and the yarn jar is fixed. By means of the scheme that the motor directly drives a spindle, the scheme in the prior art of drive through a spindle tape is replaced, the spindle can obtain a higher rotation speed, the rotation speed is increased from 4,000-6,000 rpm currently to 7,000-1,0000 rpm, and the twisting efficiency of carpet yarn is improved.

The invention discloses a screen levelness adjusting mechanism and a projection display device, relates to the technical field of display, and aims to solve the problems of complex structure, large occupied space and disadvantage in the thinning design of a screen of a conventional screen levelness adjusting mechanism. The screen levelness adjusting mechanism comprises a reference part, a support shaft, a cam, a positioning hole, a locking pin and a support plate, wherein the reference part and the support shaft are arranged on the back surface of a screen; the cam is arranged on the support shaft in a sleeving way; a plurality of locking holes are formed in the cam, and are formed at intervals in a circular arc taking the shaft center of the support shaft as the circle center; the positioning hole is formed in the back surface of the screen, and can correspond to any one locking hole; the locking pin is inserted into one locking hole and the positioning hole to lock the cam; the support plate is arranged on a screen support body; the upper surface of the support plate is in contact with the contour surface of the cam to support the cam. The screen levelness adjusting mechanism is used for regulating the levelness of the screen when the screen is suspended on the screen support body.

The invention provides a butterfly valve with an adjustable inner bypass self. The butterfly valve comprises a butterfly valve body; the interior of the butterfly valve body is divided into two regions including a valve body inner cavity A and a valve body inner cavity B; a valve seat of the valve body inner cavity A is provided with a butterfly plate A in a matching manner; a valve seat of the valve body inner cavity B is provided with a butterfly plate B in the matching manner; the butterfly plate A is connected with a valve rod A; the butterfly plate B is connected with a valve rod B; the valve rod A and the valve rod B are arranged in a nested manner; and the valve rod A rotates in the valve rod B to realize adjustment of an opening degree of the butterfly valve. For a provided novel butterfly valve structure with the inner bypass adjusting characteristic self, a special valve rod form is controlled through two different sets of executing mechanisms, and flow linear adjustment of the butterfly valve under a small opening degree can be realized. The device is simple in structure and reliable in performance and is suitable for wide-range popularization and use.

The invention provides a current-constant driving light modulation circuit of an LED of a single-stage power supply. A power supply module and a power supply control module are connected with a primary coil of a transformer, the power supply control module is connected with an on-off control module and a PWM transmission module via a control module, the control module is also connected with the primary coil of the transformer, and the on-off control module is connected with the PWM transmission module via a signal conversion module; the control module receives a switch signal output by the on-off control module and then sends a control signal to the power supply control module, and receives a PWM signal output by the PWM transmission module and then sends a corresponding light modulation signal to the power control module; the signal conversion module converts the input voltage value into the corresponding PWM signal and outputs the PWM signal to the PWM transmission module; and the PWM transmission module amplifies the input PWM signal and transmits the amplified PWM signal to the control module. The circuit efficiency is improved, the light modulation cost is reduced, and energy is saved.

The invention relates to the technical field of intelligent riding equipment, and provides a power calculation method of intelligent riding equipment, which can realize accurate adjustment of the power of a riding platform without additionally arranging various measuring equipment such as a torque sensor on the riding platform. By controlling the relative position, namely the displacement amount, between the permanent magnet in the magnetic force resistance increasing device and the inertia wheel of the riding table, the relative induction area and the magnetic induction flux between the magnet and an aluminum sheet on the inertia wheel are changed, the torque of the inertia wheel is correspondingly affected, linear adjustment of the power is achieved, corresponding specific steps are given, and the reliability of the riding table is improved. The output power data is more stable and reliable, and the accuracy of power output is improved. Meanwhile, the invention further provides intelligent riding equipment, the stepping motor is arranged to control the lead screw to rotate, namely, the displacement amount of the permanent magnet is correspondingly controlled, the displacement amount can be precisely and linearly adjusted by setting the specific numerical value of the screw pitch of the lead screw, and the stability and accuracy of power output are ensured.

The invention relates to a solenoid type electromagnetic trip, which belongs to the technical field of the low-voltage apparatus. The solenoid type electromagnetic trip comprises a knob, an adjusting rod, a spring, a moving iron core, a static iron core, a coil, a concentrating flux plate and a magnetic yoke and is characterized in that a push rod pivotally arranged at the upper end part of the magnetic yoke is also included, wherein, one end of the spring is connected with the adjusting rod, the other end of the spring is connected with the push rod, and the upper end of the moving iron coreis movably connected with the push rod after penetrating the concentrating flux plate. The invention has the advantages that the linear regulation of the current setting value for the short circuit action is realized by adjusting the length of the spring through the knob; since the adjusting screw component is arranged on the magnetic yoke, the magnetic gap can be adjusted finely, the inconsistency of the current setting values of all the trips due to the parts and the assembly is eliminated, and the consistency of the initial states of all the trips is ensured; and at least one hanging hook is arranged on the upper edge of the push rod, so that the specification of the spring is reduced when the multi-gear adjustment is realized.

The invention relates to the technical field of flow valves and provides a micro-flow regulating valve, which is high in regulating accuracy and centralized in flow area and comprises a sleeve valve seat and a valve core arranged in the sleeve valve seat. A boss is arranged in a water outlet of the sleeve valve seat, the valve core head is tightly matched with the boss, and a fluid passing through groove with an overflowing area gradually decreased along the water inlet direction is arranged on one side of a valve core head portion. Further, the fluid passing through groove is a triangular groove. The valve core enables the whole flow area to be centralized in the groove from an original annular area and enables a local area to be increased and not to be blocked by small sundries. The overflowing area of the fluid passing through groove is gradually decreased along the water inlet direction so that linear regulating can be achieved. By means of design of the triangular groove, flow regulating can be controlled accurately, processing is easy, the diameter of the valve core can be larger than that of an existing valve core, and processing strength can be ensured.

The plug valve comprises a valve body and a valve element, the valve body is provided with a valve cavity, an inlet and an outlet, the inlet and the outlet are communicated with the valve cavity, and a first ventilation opening and a second ventilation opening which are communicated with the outlet are formed in the valve cavity; the valve element is rotatably arranged in the valve cavity, an adjusting groove communicated with the inlet is formed in the valve element, the adjusting groove is opposite to the first ventilation opening and the second ventilation opening in the circumferential direction of the valve element, the valve element is provided with a first position and a third position, and the adjusting groove of the valve element is completely communicated with the first ventilation opening and staggered from the second ventilation opening at the first position; the valve element is staggered with the first ventilation opening in the third position adjusting groove and is completely communicated with the second ventilation opening, and the total communication area of the valve element, the first ventilation opening and the second ventilation opening is gradually reduced from the first position to the third position adjusting groove. By applying the technical scheme, linear adjustment of firepower can be achieved, and the adjustment range and the adjustment accuracy of the middle firepower are increased.

The invention discloses a copper processing cooling water pressure automatic control device, comprising a cooling water inlet pipe, a cooling water outlet pipe and a cooling water storage tank, wherein the cooling water inlet pipe is communicated with the cooling water storage tank, the cooling water storage tank is internally provided with a liquid level adjusting piston and a water storage inputpipe, the water storage input pipe is located above a joint between the cooling water inlet pipe and the cooling water storage tank, the liquid level adjusting piston is located below the joint between the cooling water inlet pipe and the cooling water storage tank, the bottom of the liquid level adjusting piston is connected to a piston driving connecting rod, and the bottom of the piston driving connecting rod extends out of the cooling water storage tank and is in transmission connection with a lifting drive mechanism. The copper processing cold water pressure automatic control device canrealize the linear correlation adjustment of cooling water pressure, thereby ensuring the accurate adjustment of cooling water pressure, improving the stability of production quality of an upward continuous casting machine. A water pressure regulation system has a simplified structure.

The invention discloses a double-frequency adjustable Helmholtz silencing cavity of a vehicle engine. The double-frequency adjustable Helmholtz silencing cavity comprises a rotary sleeve mounted on the outer side of a hole penetration pipe in a sleeving mode and an outer pipe mounted on the outer side of the rotary sleeve in a sleeving mode and arranged eccentric to the rotary sleeve. An eccentricring cavity is formed between the rotary sleeve, the outer pipe, an outer pipe front end cover and a rear end cover. The middle portions of the hole penetration pipe and the rotary sleeve are provided with corresponding holes. The outer circumferential surface of the rotary sleeve is provided with two blade grooves. The blade grooves extend to the two ends of the rotary sleeve in the axial direction. An expansion blade is arranged in each blade groove. An included angle theta is formed between the two expansion blades. The eccentric ring cavity is divided into an acute-angle ring cavity and an obtuse-angle ring cavity through the two expansion blades. A volume adjusting device is connected with the rotary sleeve. According to the double-frequency adjustable Helmholtz silencing cavity, therotary sleeve is driven to rotate through the volume adjusting device to change the sizes of the acute-angle ring cavity and the obtuse-angle ring cavity so as to achieve the noise elimination frequency adjustability of a silencer. The double-frequency adjustable Helmholtz silencing cavity of the vehicle engine is simple in structure, quick in response and wide in covering working condition, andthe inertia of the volume adjusting structure is small.

The invention provides a power tester of a power source. The test comprises an electronic load module, an analog-to-digital conversion module, a microprocessor module, a serial port communication module and a switching power source module. A field effect transistor is combined with an operational amplifier to form a negative feedback circuit to further control a constant current, the current is adjusted linearly, the current stability is high, sudden and rapid change is avoided, the safety is improved, a microprocessor sets the current magnitude via a DA chip of 12-bit precision, reads the digital voltage value of an analog-to-digital conversion chip of the 12-bit precision and calculates the output power, a higher test precision is ensured, a host monitors a test result via a serial portremotely, convenience is provided for intelligent test, and the power tester is simple in structure, low in cost, flexible in use and especially suitable for testing the power of multiple power sources.

The invention discloses a cylinder cover capable of controlling the flow of an oil pump, which comprises an engine lubricating system oil passage and a cylinder cover rear-end oil way which are arranged in the cylinder cover, the tail end of the engine lubricating system oil passage is communicated with the cylinder cover rear-end oil way, the cylinder cover rear-end oil way is communicated with an oil pan, and an electromagnetic valve is arranged on the cylinder cover rear-end oil way. The electromagnetic valve is connected with the ECU; the electromagnetic valve changes the rotation angle to change the engine oil drainage amount according to an ECU instruction; the ECU linearly and dynamically adjusts the rotation angle of the electromagnetic valve according to the real-time working condition data of the engine. The flow-adjustable oil pump has the advantages of reducing fuel consumption, prolonging the service life of the oil, reducing the transmission noise of the oil pump and the like.