833 results about "Hydraulic brake" patented technology

An electronic control unit for an electronic brake system, and a hydraulic assembly are disclosed. The electronic control unit comprises: a housing having a hydraulic block which is mounted on the front surface thereof and in which a plurality of valves, a flow path, and a pump are provided in order to regulate hydraulic brake pressure transmitted to a plurality of wheel cylinders; a control unit for controlling the plurality of valves and a motor which is accommodated in the housing and provides power to the pump; a first connector provided at the front surface of the housing so that the control unit can be electrically connected to an external device; and a second connector, wherein the first connector is disposed above the position at which the hydraulic block is mounted, and the second connector can be disposed below a reservoir mounted at a first side surface of the hydraulic block.

The invention relates to the technical field of loader brake valves, and discloses a hydraulic brake valve and a hydraulic system thereof.The hydraulic brake valve comprises the hydraulic brake valve, the hydraulic brake valve is composed of a one-way valve, a brake valve set, a brake lamp pressure switch, a low-pressure alarm pressure switch, a shuttle valve, a high-low pressure unloading valve and a throttling hole, and the high-low pressure unloading valve and the throttling hole are integrated; a P port, an A port, a B port, a T port, an LS1 port, an LS port, a low-pressure alarm pressure switch and a brake lamp pressure switch are arranged outside the hydraulic brake valve. A liquid filling valve is omitted, an oil source of the full-hydraulic power braking system is taken from an existing priority valve CF port of equipment, pressure feedback signals are selected through a shuttle valve on a hydraulic braking valve, the pressure feedback signals are transmitted to the priority valve, and liquid filling and energy supplementing of the full-hydraulic power braking system or steering work of a steering system is achieved. The brake has the remarkable advantages of being fast in brake response, low in noise, low in failure rate, high in safety coefficient, compact in structure, low in cost and low in energy consumption.

The present invention discloses a hydraulic brake valve and its exhaust process method. The valve body of the exhaust structure touches and presses the operating mechanism at the top of the valve body component of the valve body. A working spring is installed on the valve plug of the valve body. The valve core is installed in the central hole of the valve body and the central counterbore of the plug. The valve core is inserted into the center of the plug, and the counterbore presses the return spring. The return spring is installed on the spring seat, and the spring seat is installed in the counterbore of the plug. The roller of the operating mechanism touches and presses the plug in the valve body to form action and reaction forces, and promotes the operating mechanism and the valve core to touch and press and move to work. The valve core can slide along the inner wall of the valve body. An exhaust hole is provided on the side wall of the valve core. A plug for blocking the other end of the valve body is provided in the valve body, and a spring seat abutting against the plug is further provided in the plug. A return spring is installed between the spring seat and the valve core. The advantages are: avoiding abnormal noises and cavitation phenomena caused by gas accumulation to the hydraulic brake valve, ensuring the normal transmission and circulation of hydraulic oil in the pipeline, and eliminating potential hazards of the hydraulic braking system.

The application discloses an intelligent electric chassis configuration and a fault-tolerant control method of the intelligent electric chassis, and relates to the technical field of electric chassis. The chassis configuration comprises a front axle centralized motor drive assembly, a rear axle distributed motor drive assembly, a front axle electronic hydraulic brake system, a rear axle electronic mechanical brake system and a chassis domain controller. The front axle centralized motor drive assembly comprises a centralized drive motor, a front wheel speed reducer and a drive half shaft which are sequentially connected. The rear axle distributed motor drive assembly comprises a left rear wheel end drive motor and a left rear wheel speed reducer which are sequentially connected, and a right rear wheel end drive motor and a right rear wheel speed reducer which are sequentially connected. The front axle electronic hydraulic brake system comprises a first main brake unit and a redundant brake unit. The rear axle electronic mechanical brake system comprises a second main brake unit. The chassis domain controller is used for controlling the centralized drive motor, the left and right rear wheel end drive motors, the first main brake unit, the redundant brake unit, the second main brake unit, a front axle steer-by-wire system, an intelligent suspension system and an intelligent tire. The application can improve the chassis safety and fault-tolerant capability to support high-level automatic driving functions.

A brake system for hydraulically actuating a pair of front wheel brakes and a pair of rear wheel brakes includes a master cylinder fluidly connected to a reservoir and operable to provide a brake signal responsive to actuation of a brake pedal connected thereto. The master cylinder is selectively operable during a manual push-through mode by actuation of the brake pedal to generate brake actuating pressure at an output for hydraulically actuating a selected one of the pair of front and rear wheel brakes. A first power transmission unit is configured for actuating the selected one of the pair of front and rear wheel brakes. A second power transmission unit is configured for actuating the other one of the pair of front and rear wheel brakes. A first electronic control unit is provided for controlling at least one of the first and second power transmission units.

The invention discloses an unmanned mining dump truck hydraulic braking system and a control method. The unmanned mining dump truck hydraulic braking system comprises a service brake valve set and a parking brake valve set. The service brake valve group comprises a first hydraulic proportional pressure reducing valve, a second hydraulic proportional pressure reducing valve, a first shuttle valve and a first pressure sensor; the first hydraulic proportional pressure reducing valve and the second hydraulic proportional pressure reducing valve are connected in parallel; oil outlets of the first hydraulic proportional pressure reducing valve and the second hydraulic proportional pressure reducing valve are communicated with an oil inlet of a first shuttle valve; an oil outlet of the first shuttle valve is connected with a first pressure sensor; the parking brake valve group comprises an electromagnetic directional valve, a redundant electromagnetic directional valve and a pressure switch; the electromagnetic directional valve is a normally closed valve, and the redundant electromagnetic directional valve is a normally open valve; the electromagnetic directional valve and the redundant electromagnetic directional valve are connected in series, the electromagnetic directional valve is connected with an oil inlet pipeline, the redundant electromagnetic directional valve is connected with an oil outlet pipeline and a parking brake caliper, and a pressure switch is arranged on the oil outlet pipeline.

The invention discloses a braking energy distribution method and system based on braking noise prediction and electronic equipment. The method comprises the steps that braking noise time sequence data, vehicle speed time sequence data, hydraulic braking torque time sequence data and pedal travel time sequence data of a current vehicle are obtained; inputting the braking noise time sequence data, the hydraulic braking torque time sequence data and the pedal travel time sequence data into a pre-trained braking noise prediction model to obtain a braking noise prediction value of the current vehicle after a preset time step; determining a corresponding braking noise threshold value according to the current working condition and the current driving mode of the current vehicle; and when the braking noise prediction value is larger than the braking noise threshold value, the braking energy distribution proportion is adjusted, so that the energy recovery torque is increased, and the hydraulic braking torque is reduced. According to the method, the braking noise of the vehicle is maintained below the threshold value through dynamic distribution of the braking energy, interference to users in the vehicle is avoided, the driving comfort of the vehicle is improved, and the method can be applied to the technical field of vehicle control.

The invention discloses an enhanced braking system for a mountain railway vehicle, which relates to the technical field of railway vehicle braking control, and comprises the following steps: acquiring a rail position vector and an arc length, calculating a rail curvature and a rail gradient, and combining the current speed and the target speed of the vehicle to solve a braking demand acceleration value and generate a gradient parameter and a curve parameter; according to the braking force distribution proportion, a wheel rail hydraulic braking torque value is adjusted, the meshing depth and the vibration frequency of a rack rail brake are controlled through a rack rail action instruction, and a wheel rail system state report and a rack rail work log are generated; and gradient parameters, actual adhesive force numerical values and toothed rail meshing efficiency in the braking process are extracted from a wheel-rail system state report and a toothed rail work log, and closed-loop optimization is carried out in combination with a terrain braking curve. Self-learning and self-adaptive adjustment are carried out on the braking process through closed-loop feedback and parameter optimization, so that the energy utilization efficiency is improved and the service life of key components is prolonged while the braking efficiency is guaranteed.

The invention belongs to the technical field of vehicle braking control, and provides a vehicle braking system failure auxiliary processing method, system and device and a medium. When the state is a non-failure state, executing a pressure building braking strategy; when the vehicle is in the failure state, an auxiliary processing strategy is executed, and the auxiliary processing strategy comprises the steps that the braking intention is judged based on vehicle braking feedback, and vehicle stability control threshold setting, deceleration distribution of electric braking and hydraulic braking, active adjustment of the braking pressure and active adjustment of the motor torque are sequentially completed based on the judgment result; and the wheel slip rate of the vehicle is monitored in real time, and the steering force of the vehicle is corrected in combination with vehicle braking feedback. While the deceleration of the vehicle meets the requirement of a driver, drifting or rollover of the vehicle due to the fact that the driver suddenly turns the steering wheel can be avoided, so that the stability of the vehicle is ensured.

The invention provides a control method and device which can be applied to the field of intelligent driving. The method comprises the steps that the electric braking recovery torque of a front axle and the electric braking recovery torque of a rear axle of the vehicle are obtained, and the ratio of the electric braking recovery torque of the front axle to the electric braking recovery torque of the rear axle is smaller than a preset distribution ratio; when hydraulic braking torque compensation is triggered, the hydraulic braking torque of the front axle is determined according to the electric braking recovery torque of the rear axle, the braking torque determined according to the preset distribution ratio and the electric braking recovery torque of the front axle; and controlling a hydraulic brake of the front axle to work according to the hydraulic braking torque of the front axle. The embodiment of the invention can be applied to an intelligent automobile or a new energy automobile, and is helpful for preventing the EBD function from being triggered too early in a vehicle braking process.

A hydrostatic rotary machine includes (i) an inner element and an outer element which are coaxial and mounted with the ability to rotate one with respect to the other about an axis of rotation, one of these elements being a rotor and the other of these elements being a stator, (ii) a brake counter-disc which is mounted on the distribution hub, which extends radially around the distribution hub, and which is rotationally coupled to the outer element, (iii) a passive-braking piston designed to activate a brake under the effect of an elastic element and which is mounted with axial mobility with respect to the brake counter-disc, and (iv) a hydraulic brake-release chamber positioned between the brake counter-disc and the passive-braking piston.

The invention relates to the field of tire type walking equipment, and discloses a load-sensitive hydraulic brake valve and a load-sensitive hydraulic system thereof, and the load-sensitive hydraulic system comprises the load-sensitive hydraulic brake valve, a load-sensitive pump, a priority valve, a steering hydraulic system, a working hydraulic system, a shuttle valve and corresponding connecting pipelines; a P port, an A port, a B port, a T port, an LS1 port, an LS port, a low-pressure alarm pressure switch and a brake lamp pressure switch are arranged outside the load-sensitive hydraulic brake valve. According to the system, full-hydraulic dynamic braking can be achieved on equipment without a prefill valve, the equipment efficiency is improved, the installation cost is reduced, the energy consumption is reduced, and the service life is prolonged. Wherein the load-sensitive hydraulic brake valve integrates a brake function, a pressure maintaining function, a high-low pressure switching function, a pressure signal selection function and a pressure alarm function; the invention has the advantages of fast braking response, low noise, low failure rate, high safety coefficient, compact structure, low cost, low energy consumption and long service life.

The invention provides a longitudinal control method and device.The longitudinal control method can be applied to a longitudinal control system composed of an automatic driving controller, a motor controller and a hydraulic braking controller, and the method comprises the steps that the automatic driving controller obtains braking demand torque; the automatic driving controller sends a first instruction to the motor controller and sends a second instruction to the hydraulic braking controller according to the relation between the braking demand torque and the maximum recovery torque of the motor controller; the motor controller controls the driving motor to perform electric braking according to the first instruction; and the hydraulic brake controller controls the hydraulic actuator to execute corresponding operation according to the second instruction. The embodiment of the invention can be applied to an intelligent automobile or an electric automobile, and is helpful for reducing the time delay in the braking process, thereby being helpful for improving the driving safety of a user.

A brake system for a vehicle may include at least two hydraulic brake circuits, each having at least one hydraulically acting wheel brake, at least two pressure supply devices, each of which is driven by an electromotive drive, at least one valve assembly having valves for the wheel-individual adjustment of brake pressures and / or for separating the wheel brakes from, or connecting same to, a pressure supply device, at least one electronic control and regulating unit, one of which is a superordinate central control unit that controls individual control and regulating units of the components of the brake system, as well as at least one additional electric drive motor for at least one axle or wheel of the vehicle. The brake system may use the at least one pressure supply device and / or the at least one electric drive motor for controlling pressure in at least one wheel brake for steering interventions.

An electric hydraulic brake includes: wheel brakes configured to braking force to wheels of a vehicle; a reservoir storing brake oil; a master cylinder connected to the reservoir, and operated in conjunction with a main brake motor to generate pressure of the brake oil; a first controller configured to control the main brake motor; a hydraulic controller including a pump configured to form pressure of the brake oil in conjunction with an auxiliary brake motor, and a hydraulic block configured to selectively transmit the pressure of the brake oil formed in the master cylinder or the pump to the wheel brakes; and a second controller configured to control the auxiliary brake motor when the master cylinder or the first controller malfunctions. The hydraulic controller is provided with an auxiliary flow path to transmit the brake oil from the reservoir to the pump directly through the auxiliary flow path.

Braking system with: a hydraulic brake device for generating a friction braking force comprising a pedal (16), at least one brake caliper (21a - 21d) a main pressure generating device (200) with a main cylinder (212) and a piston (251) which pressurizes the main cylinder (212), a wheel pressure generating device (300) for generating a hydraulic pressure in the at least one brake caliper (21a - 21d); and a regenerative braking device (18) and a brake control device (100) for calculating a braking force distribution between friction brakes and regenerative braking, wherein the braking system is configured to adjust a total braking force (Ft) based on a pedal reaction force and a displacement amount of the piston (251) that pressurizes the master cylinder (212), or adjust the total braking force (Ft) based on the pedal reaction force and the generated hydraulic pressure in the at least one brake caliper (21a - 21d) to keep the total braking force (Ft) at a constant level when transitioning from regenerative braking to friction braking in response to a reduction in vehicle speed.

The utility model discloses an electronic pedal structure for brake-by-wire, which comprises a pedal support and a pedal arm rotationally connected to the pedal support through a pedal shaft, and further comprises a pedal simulator arranged below the pedal arm, the pedal simulator is provided with a central axis, and the pedal simulator can stretch out and draw back in the extending direction of the central axis. The two ends of the pedal simulator in the telescopic direction are flexibly connected with the pedal arm and the pedal support respectively, the pedal support is provided with a mounting face, the included angle between the mounting face and the central axis ranges from 80 degrees to 100 degrees, and projections of the pedal shaft and the pedal simulator on the plane where the mounting face is located are staggered. The height of the pedal support in the electronic pedal structure is small, so that the structural size of the pedal support is small; in addition, the electronic pedal structure and an original hydraulic brake pedal can be installed on an automobile in a replaceable mode, and therefore the transition requirement of the hydraulic pedal and the electronic pedal is met in stages.

A brake traction control system (BTCS) using a redundancy braking system includes a main braking force adjusting device configured to control a hydraulic brake of a vehicle, a sensor unit configured to detect a driving state of the vehicle, an electronic brake electrically operating and configured to generate braking force for at least one driving wheel, and an auxiliary braking force adjusting device configured to control the hydraulic brake and the electronic brake when a failure occurs in the main braking force adjusting device, wherein the auxiliary braking force adjusting device is configured to adjust the braking force of the electronic brake provided on at least one wheel on left and right sides of the vehicle based on a detected value of the sensor unit.

A method, a device, a controller, and a computer program product for comfortable braking are disclosed. The method includes (i) determining a comfortable braking force based on an openness of a brake pedal of a vehicle, (ii) obtaining a current hydraulic braking force of the vehicle, (iii) requesting a drive force from a vehicle control unit in response to the hydraulic braking force being greater than the comfortable braking force, and (iv) performing comfortable braking on the vehicle based on the hydraulic braking force and the drive force. The above method enables the realization of the comfortable braking function with the participation of hydraulic brakes, which improves the flexibility of the comfortable braking by simultaneously utilizing the hydraulic braking force and the drive force, and expands the application scene of the comfortable braking, thereby improving the ride experience of drivers and passengers.

Provided are a vehicle control method and system, and a vehicle and a storage medium. The vehicle control method comprises: in response to the fact that a vehicle enables a comfort stop function, acquiring a longitudinal acceleration and a requested braking force of the vehicle; on the basis of the longitudinal acceleration, determining a parking braking force of the vehicle; in response to the fact that the parking braking force is greater than the requested braking force, acquiring a current vehicle speed; and in response to the fact that the current vehicle speed is less than a first preset vehicle speed threshold value, outputting a first control signal to control the vehicle, wherein the first control signal is used for controlling a hydraulic braking force of the vehicle to ramp down according to a preset slope and controlling an electric-motor braking force to replace the hydraulic braking force according to the preset slope. By replacing the hydraulic braking force with the electric-motor braking force, the vehicle can be stably parked, and thus the problem of vehicle jerking when the vehicle is braked for parking can be solved.

An oil pressure brake with a double-sealing structure comprises a brake pump body, a brake handle and an oil pipe assembly. The brake pump body is provided with a pressure cylinder and an oil storage cylinder, a piston push rod assembly acted by the brake handle is arranged in the pressure cylinder, and the pressure cylinder is communicated with the oil storage cylinder through an oil pressure adjusting hole. The piston push rod assembly comprises a front piston rod and a rear piston rod, a pushing cavity is formed in the rear piston rod, and the front piston rod can enter the pushing cavity; the front piston rod is provided with an oil guide cavity and an oil overflow hole; the front piston rod is further sleeved with a one-way piston oil seal, the one-way piston oil seal abuts against the inner wall of the pressure cylinder, and the one-way piston oil seal is located on the front side of the oil overflow hole. The hydraulic brake has the advantages that a new oil way is formed through the oil guide cavity and the oil overflow hole formed in the front piston rod, so that only one oil pressure adjusting hole is reserved between the pressure cylinder and the oil storage cylinder, only one one-way piston oil seal is used on the piston push rod assembly, and the brake use function can be achieved.

A brake system may include a plurality of wheel speed sensors respectively installed in a plurality of wheels of a vehicle, a plurality of hydraulic brake modules related to braking of the plurality of wheels, and a first controller configured to perform braking control on the plurality of hydraulic brake modules in response to at least one of a pedal displacement signal, which corresponds to a movement of a brake pedal, and wheel speed signals outputted from the wheel speed sensors, in which when a failure of the first controller is identified, a second controller, which is provided in a steering system of the vehicle, performs braking control on an electronic parking brake, which is provided in at least one of the plurality of wheels, in response to at least one of an operating signal of an EPB switch, the pedal displacement signal, and the wheel speed signals outputted from the wheel speed sensors.

The invention provides a vortex hydraulic segmented disc brake, and belongs to the technical field of brakes. The brake disc is rotatably mounted on the brake frame, and one end of the brake disc is used for being connected with a roller of the belt conveyor; the brake assembly comprises an electromagnetic induction brake part and a hydraulic brake part and is arranged at the two ends of the brake disc; when the brake brakes, and the rotating speed of the brake disc is higher than a first preset rotating speed, the electromagnetic induction brake part performs electromagnetic eddy current braking on the brake disc; when the rotating speed of the brake disc is lower than the first preset rotating speed and higher than the second preset rotating speed, the electromagnetic induction brake part and the hydraulic brake part jointly brake the brake disc; and when the rotating speed of the brake disc is lower than a second preset rotating speed, the hydraulic brake part performs friction braking on the brake disc. Sparks and abrasion generated during traditional friction braking are reduced, the service life of the brake disc and the service life of the brake block are prolonged, and the safety of underground operation of the mining belt conveyor is remarkably improved. The invention further provides a belt conveyor.

The utility model relates to a mechanical and electrical integrated brake caliper. According to the technical scheme, the mechanical and electrical integrated brake caliper comprises a caliper body, two hydraulic brake pads and two motor brake pads. A mounting groove is formed in the calipers; the two hydraulic brake pads are slidably mounted on the two sides of one end of the mounting groove correspondingly. A hydraulic driving module is arranged on the calipers; the output end of the hydraulic driving module abuts against the two hydraulic brake pads. A motor driving module is further arranged on the calipers; one motor brake pad is fixedly mounted on one side of one end, far away from the hydraulic brake pad, of the mounting groove; the other motor brake pad is slidably mounted on the other side of the end, away from the hydraulic brake pad, of the mounting groove and abuts against the output end of the motor driving module. The brake caliper is stable in overall structure and convenient to install, a hydraulic caliper structure and an electronic caliper structure can be combined into a mechanical and electrical integrated brake caliper, and the integrated structure is higher in stability and safety; the space is saved, and meanwhile the parking effect is reserved.

A braking system for a motor vehicle has a plurality of hydraulic brake units for braking each braking one wheel of the motor vehicle and a first electric parking brake actuator for braking a first wheel and a second electric parking brake actuator for braking a second wheel. A first control device comprises a first hydraulic controller which is designed and set up to drive the plurality of hydraulic brake units. In order to ensure parking brake redundancy, the first control device has a driver for driving the first parking brake actuator. A second control device is also provided, which comprises a driver for driving the first parking brake actuator and a driver for driving the second parking brake actuator.

Disclosed are a hydraulic brake device, a hydraulic brake actuation device, and a two-wheeled vehicle. The hydraulic brake device comprises a cylinder body, a pushrod piston, and a return spring. One end of the pushrod piston moves back and forth within the cylinder body, overcoming the elastic force of the return spring. A pushrod head is provided at the other end of the pushrod piston.The hydraulic brake actuation device comprises a carrier, an actuating lever and the hydraulic brake device, wherein the actuating lever is rotatably connected to the carrier; the hydraulic brake device is symmetrically constructed and provided within the carrier; a drive rod is arranged on the carrier, wherein the head end of the drive rod is in contact with the actuating lever and the rear end of the drive rod is in contact with the hydraulic brake device; the drive rod serves to receive a drive force from the actuating lever.

The invention provides an energy recovery control method and device, a vehicle and a storage medium, and the method comprises the steps: monitoring the current driving working condition of the vehicle, and obtaining vehicle operation parameters, the current hydraulic braking force of vehicle braking and the current feedback braking force of a vehicle motor when the current driving working condition is a braking working condition; and the vehicle operation parameters, the current hydraulic braking force and the current feedback braking force are subjected to torque prediction through a pre-trained prediction model, target recovery torque is obtained, and a vehicle motor and a vehicle brake are controlled to output braking torque to a vehicle power system according to the target recovery torque. According to the method, it is monitored that the vehicle is in the braking working condition, the target recovery torque matched with the vehicle running parameters, the hydraulic braking force and the feedback braking force is rapidly and accurately predicted by combining the prediction model with the real-time vehicle running condition in time, cooperative control is conducted on a motor and braking through the recovery torque, and energy recovery with the maximum vehicle efficiency is achieved.

Disclosed are a bicycle hydraulic brake control device and a bicycle. The bicycle hydraulic brake control device includes: a control main body connected to a handlebar of a bicycle; a brake lever pivotally connected to an end of the control main body; a hydraulic cylinder connected to the control main body; a piston rod connected to the hydraulic cylinder; and a trigger member hinged to the control main body, wherein the trigger member includes a pressing portion and a pushing portion. In the brake control device, the piston rod is pushed by means of the rolling member to do a piston motion, so that hard friction between the trigger member and the piston rod is prevented to reduce the friction force between the trigger member and the piston rod and achieve a smooth hand feeling of braking, the braking effect is improved, and a rider's braking experience is also improved.

The stretching linkage equipment comprises a traction machine and the tension machine, the traction machine comprises a traction machine frame, a traction winding drum and a guide mechanism, the traction winding drum is installed on the traction machine frame, and the guide mechanism is arranged on the traction machine frame; the tension machine comprises a tension machine frame, an output shaft and a tension winding drum, the tension winding drum is rotationally arranged on the tension machine frame, and the output shaft is fixedly connected to the tension winding drum; a hydraulic resistance braking mechanism is fixedly arranged on the tension rack, and the hydraulic resistance braking mechanism is arranged on the output shaft in a sleeving manner; the tension machine further comprises a gear motor, and the gear motor is arranged on the tension machine frame. The hydraulic resistance braking mechanism comprises a liquid disc, a closed liquid cavity filled with magnetorheological fluid is arranged in the liquid disc, a resistance wheel set is arranged in the liquid cavity, and the resistance wheel set comprises a rotatable resistance blade and a motor; and a magnetic field regulation and control mechanism is arranged outside the liquid disc. The technical problem that hydraulic braking of existing stretching equipment fails is solved by integrating the hydraulic resistance braking mechanism and the magnetic domain regulation and control mechanism through the tensioner.

A hydraulic brake system for activating the wheel brakes of an aircraft landing gear assembly includes a hydraulic fluid supply line and an associated return line. There is a valve which separates a source of hydraulic fluid from a portion of the return line and an associated leak path associated with the valve that in use maintains the pressure and / or volume of hydraulic fluid in the portion of the return line above a minimum acceptable level. The leak path may be provided by a hole drilled in a part (e.g. the poppet) of a non-return check valve.