Low resistance flow regulator

The present teachings provide for a flow restrictor for a coolant line of an internal combustion engine coolant system. The flow restrictor can include a restrictor element and a biasing member. The restrictor element can include a restrictor plate and a tab non-rotatably coupled at an angle. The biasing member can rotationally bias the restricting element to a first position where the restricting plate is substantially parallel to the flow of fluid. The tab can be configured to create a torque on the restricting element to overcome the biasing member and rotate the restricting plate to block a portion of the fluid flow path when the flow exceeds a predetermined flow rate.

FIELD

The present disclosure relates to low resistance flow regulators, such as, low resistance flow regulators for regulating flow of engine coolant.

BACKGROUND

Internal combustion engines, such as gasoline or diesel engines, for example, often have a coolant system to remove heat from the engine that would otherwise have detrimental effects on fuel economy, engine performance, and longevity. Typical coolant systems include at least a pump, a heat exchanger, such as a radiator for example, coolant fluid, and various tubes, hoses, or passages to convey the fluid between the engine and the heat exchanger. Coolant systems can also include a thermostat, which typically blocks coolant flow through the system until the engine warms up to a predetermined operating temperature, and then allows full flow thereafter. The fluid can be pumped through passages in the engine to absorb heat generated by combustion. The heated fluid can then pass through the heat exchanger to release the heat, typically to the atmosphere.

The flow rate of the fluid through the system can be important to ensure optimal cooling of the engine. In order to vary flow rate of the fluid, coolant pumps are typically rotationally driven by a belt connected to a pulley mounted to the engine crankshaft. In this way, the pump speed, and therefore the fluid flow rate, is proportional to the engine speed, i.e. revolutions per minute (RPM). As the engine RPMs increase, the coolant flow rate increases. In some situations, this configuration is preferable in order to roughly correspond cooling capacity with heat production from the engine. However, it has been found that certain high RPM conditions can produce flow rates that exceed the necessary cooling capacity, and/or can be detrimental to various components of the cooling system. Specifically, higher flow rates can lead to increased erosion of the internal passages of the heat exchanger, which can shorten the lifespan of the heat exchanger. The desirable flow rate ranges can vary with application and equipment, but for example some coolant systems have been found to produce flow rates in excess of 450 liters per minute in certain high RPM conditions, while only requiring flow rates in the order of 220 liters per minute.

Prior solutions to regulate coolant flow have typically been complex, costly, or resulted in restricted flow at lower flow rates. For example, some coolant systems use complex valves, other systems use devices that restrict flow at all flow rates, or become closed to flow when certain flow or pressure conditions are exceeded. Other systems are known to decouple the pump operation from the engine speed by utilizing an electrically driven pump. Flow rates of these electric pumps can be controlled based on temperature and flow rate sensors. However, the cost and complexity of such systems can be undesirable. Accordingly, a need exists for an improved internal combustion engine coolant system having low resistance during low RPM conditions, while regulating flow during high RPM conditions.

SUMMARY

The present teachings provide for a flow restrictor for a coolant line of an internal combustion engine coolant system. The flow restrictor can include a restrictor element and a biasing member. The restrictor element can be configured for rotation about a pivot axis within a flow path of the coolant line. The restrictor element can include a first restrictor plate and a tab. The first restrictor plate can extend in a first direction. The tab can extend in a second direction different than the first direction. The biasing member can be configured to generate a first torque about the pivot axis to bias the restrictor element toward a first rotational position. In the first rotational position, the first restrictor plate can be substantially parallel to a central axis of the flow path. A second torque about the pivot axis is generated when a fluid flows through the flow path and contacts the tab. The second torque can be opposite the first torque and can exceed the first torque to rotate the restrictor element to a second rotational position when the fluid flows through the flow path at a flowrate greater than a first predetermined flowrate. The first restrictor plate can be configured to block a portion of the flow path to limit the fluid to a second predetermined flowrate.

The present teachings further provide for a coolant system for an internal combustion engine. The coolant system can include a coolant conduit, a flow restrictor, and a biasing member. The coolant conduit can define a flow passageway configured to circulate a coolant fluid through the coolant conduit. The flow restrictor can be disposed within the flow passageway and can include a pivot member, a first restrictor plate, and a tab. The pivot member can be rotatably coupled to the coolant conduit and configured to rotate about a pivot axis. The first restrictor plate can be fixedly coupled to the pivot member and can extend radially therefrom. The tab can be fixedly coupled to the pivot member and can extend radially therefrom at an angle relative to the first restrictor plate. The biasing member can be configured to bias the pivot member toward a first rotational position. A torque about the pivot axis is generated when the coolant fluid flows through the flow passageway and contacts the tab. When the coolant fluid flows through the flow passageway at a flowrate greater than a predetermined flowrate the torque can overcome the biasing member to rotate the pivot member to a second rotational position. When in the first rotational position, a first area of the flow passageway can be restricted by the tab. When in the second rotational position, a second area of the flow passageway can be restricted by the restrictor plate. The second area can be greater than the first area.

The present teachings further provide for a coolant system for an internal combustion engine. The coolant system can include a heat exchanger, a coolant circuit, a flow restrictor, and a biasing member. The heat exchanger can include an inlet port and an outlet port. The coolant circuit can include a supply conduit and a return conduit. The supply conduit can be coupled for fluid communication with the inlet port and can define a supply passageway configured to convey a coolant fluid from the engine to the heat exchanger. The return conduit can be coupled for fluid communication with the outlet port and can define a return passageway configured to convey the coolant fluid from the heat exchanger to the engine. The flow restrictor can be disposed within one of the supply passageway or the return passageway. The flow restrictor can include a pivot member, a first restrictor plate, and a tab. The pivot member can be rotatably coupled to the one of the supply conduit or the return conduit that the flow restrictor is disposed within and can be configured to rotate about a pivot axis. The first restrictor plate can be fixedly coupled to the pivot member and can extend radially therefrom in a first direction. The tab can be fixedly coupled to the pivot member and can extend radially therefrom in a second direction different than the first direction. The biasing member can be configured to bias the pivot member toward a first rotational position. In the first rotational position, the first restrictor plate can be substantially parallel to a central axis of the one the supply passageway or the return passageway. A torque about the pivot axis is generated when a fluid flows through the one of the supply passageway and the return passageway and contacts the tab. When the coolant fluid flows through the coolant circuit at a flowrate greater than a predetermined flowrate the torque can overcome the biasing member to rotate the pivot member to a second rotational position. When in the first rotational position, a first area of the one of the supply passageway or the return passageway can be restricted by the tab. When in the second rotational position, a second area of the one of the supply passageway or the return passageway can be restricted by the restrictor plate. The second area can be greater than the first area.

DETAILED DESCRIPTION

With reference toFIG. 1, a vehicle10is illustrated as having an internal combustion engine14and a coolant system18. In the example provided the vehicle10is illustrated as a truck, however, it is understood that the vehicle10can be any type of vehicle having an internal combustion engine, such as a passenger car, bus, recreational vehicle, military vehicle, aircraft, or watercraft for example. It is also understood that the coolant system18may be used with an internal combustion engine not disposed in a vehicle, such as a generator, agricultural machinery, industrial machinery, construction equipment, or military equipment for example. In the example provided, the coolant system18is located at a front portion22of the vehicle10, although other configurations or locations can be used.

The engine14can include an engine block26, a crankshaft (not shown), a drive pulley34, and a belt38, for example. It is understood that the engine14can be any type of internal combustion engine, such as a piston-cylinder engine or a rotary engine, for example. The engine block26can define an engine inlet42, an engine outlet46, and at least one engine passage (not shown) extending through a portion of the engine block26. It is understood that the engine passage can pass through other portions of the engine14as well, such as a cylinder head of a piston-cylinder engine for example. The engine passage can be in fluid communication with the engine inlet42and the engine outlet46to allow a coolant fluid (not shown) to flow through the engine block26and absorb heat from the engine14.

The crankshaft can be rotatably mounted within the engine block26and configured to be coupled to a prime mover element (not shown) within the engine block26. The prime mover element can be any type of prime mover element configured to translate combustion energy into rotation of the crankshaft, such as a piston of a piston-cylinder engine, or a rotor of a rotary engine for example. The drive pulley34can be non-rotatably coupled to the crankshaft to rotate therewith. The drive pulley34can be coupled to the belt38to rotatably drive the belt38.

The coolant system18can include a heat exchanger54, a supply conduit58, a return conduit62, a pump66, and a flow restrictor70. The coolant system18can further include a thermostat74. The heat exchanger54can be any type of heat exchanger, such as a radiator, or a parallel plate heat exchanger for example, for example.

In the example provided, the heat exchanger54is a radiator having a radiator body78, a plurality of tubes82, a plurality of fins (not shown). The radiator body78can have a first face90and a second face (not shown) opposite to the first face90, and can define a radiator inlet98and a radiator outlet102. In the example provided, the radiator body78is generally rectangular in shape, although other configurations can be used.

The tubes82can extend through the radiator body78and be configured to allow the coolant fluid to flow through the tubes82. The radiator inlet98and radiator outlet102can be in fluid communication with opposite ends of the tubes82to allow the coolant fluid to pass from the radiator inlet98, through the tubes82, and to the radiator outlet102. The tubes82can be arranged in the radiator body78such that air can flow through the first face90and pass over the tubes82before exiting the radiator body78through the second face.

The air passing over and between the tubes82can absorb heat from the coolant fluid to dissipate the heat to the atmosphere. The coolant fluid can be any type of coolant liquid such as anti-freeze, or water for example. In the example provided, the tubes82are parallel and horizontally oriented with regard to the radiator body78, although other configurations can be used, such as vertical tubes or serpentine tubes, for example. The fins can extend between the tubes82to assist in the dissipation of heat from the coolant fluid as it passes through the tubes82. In the example provided, the heat exchanger54dissipates heat to the atmosphere, although other configurations can be used, such as dissipating heat to inside a passenger compartment of the vehicle10, or to a secondary coolant system (not shown) via a second coolant fluid (not shown), for example. While the natural airflow passing through the radiator body78, between the fins and tubes82, can carry heat away from the heat exchanger54, a fan (not shown) can be used to force air through the radiator body78. In the example provided, the heat exchanger54is located toward the front22of the vehicle10, although other locations can be used.

The supply conduit58can have a first end106and a second end110. The first end106can be proximate to the engine14and coupled for fluid communication with the engine outlet46. The second end110can be proximate to the heat exchanger54and coupled for fluid communication with the radiator inlet98. The return conduit62can have a third end114and a fourth end118. The third end114can be proximate to the heat exchanger54and coupled for fluid communication with the radiator outlet102. The fourth end118can be proximate to the engine14and coupled for fluid communication with the engine inlet42. Thus the supply conduit58and return conduit62can form a coolant circuit122for circulating the coolant fluid from the engine14, through the supply conduit58, to the heat exchanger54, and back to the engine14through the return conduit62. It is understood that some of the coolant fluid can be diverted to, and returned from, other components not shown, such as a heater core for a heating, ventilation, and air conditioning (HVAC) system for example.

The pump66can be any type of pump for pumping the coolant fluid through the coolant circuit122, such as an impeller pump for example. The pump66can be inline with the coolant circuit122and configured to circulate the coolant fluid through the supply conduit58, the return conduit62, the engine14, and the heat exchanger54. The pump66can be mounted to the engine14and drivingly coupled to the engine14. The pump66can have a pump pulley126that can be coupled to the belt38to be rotatably driven by the crankshaft by way of rotation of the belt38. Rotation of the pump pulley126can cause the pump66to circulate the coolant fluid within the coolant circuit122. In the example provided, the pump66is inline with the return conduit62, between the fourth end118and the engine inlet42, but other locations along the coolant circuit122can be used, such as inline with the supply conduit58for example.

The thermostat74can have a thermostat body130, a valve (not shown) and a sensing element (not shown). The thermostat body130can be inline with the coolant circuit122at any location within the coolant circuit122to prevent flow of the coolant fluid through the coolant circuit122, as will be described below. In the example provided, the thermostat body130is inline with the supply conduit58, between the first end106and second end110, though other configurations can be used, such as between the engine outlet46and first end106, mounted to the radiator inlet98or radiator outlet102, inline with the return conduit62, between the fourth end118and the engine inlet42, or inline with the engine passage, for example.

The valve can be disposed in the thermostat body130and can be configured move between a closed position and an open position. In the closed position, the valve blocks flow of the coolant fluid through the thermostat body130, to prevent flow through the heat exchanger54. In the open position, the valve allows flow of the coolant fluid through the thermostat body130to allow flow through the heat exchanger54. The sensing element can be configured to move the valve between the open and closed positions. The sensing element and valve can be configured such that the valve is in the closed position when the temperature of the coolant fluid is below a predetermined temperature. The sensing element and valve can be configured such that the valve is in the open position when the temperature of the coolant fluid is at or above the predetermined temperature. The predetermined temperature can correspond to a minimum recommended operating temperature of the engine14. In this way, the thermostat74prevents the coolant system18from removing heat from the engine14until the engine14reaches a desired minimum operating temperature.

The thermostat74can be operated mechanically, such that the sensing element can physically change states, or position, based to the temperature of the coolant fluid, causing the valve to be opened or closed, as is known in the art. For example, the sensing element can include a substance (not shown), typically a wax, within the thermostat74that can melt at the predetermined temperature, which can cause the valve to open. When the temperature of the coolant fluid drops below the predetermined temperature, the substance can reconstitute back to its original form to cause the valve to close. The thermostat74can be configured to generally be either fully open or fully closed. The thermostat can alternatively be operated by an electro-mechanical actuator (not shown), and the sensing element can be configured to send an electrical signal to the electro-mechanical actuator to move the valve between the open and closed positions based on the temperature of the coolant fluid relative to the predetermined temperature. Thermostats are generally either fully open or fully closed, and operate based on temperature, not based on flow rate.

The flow restrictor70can be inline with the coolant circuit122. In the example provided, the flow restrictor70is inline with the supply conduit58, between the first end106and the second end110, although other configurations can be used. For example, the flow restrictor70can be inline with the return conduit, or mounted to the radiator inlet98, or radiator outlet102for example. The flow restrictor70can also be mounted to, or integrally formed with the thermostat body130.

With reference toFIGS. 2-4, the flow restrictor70can have a main body210, a restricting element214, and a biasing member218. The main body210can have an upstream end222and a downstream end226, an exterior230, and can be generally hollow to define a flow path234between the upstream end222and downstream end226. The main body210can also have a stop element238and can define a pivot aperture242that can extend through the main body210between an inner surface250and the exterior230.

The main body210can be configured to allow the coolant fluid to flow in a flow direction246through flow path234. The flow path234can be a generally cylindrical shape defined by the inner surface250and having a central axis254parallel to the flow direction246. While the flow path234of the present example is generally cylindrical, other configurations may be used.

The restricting element214can include a pivot rod258, a restricting plate262, and a tab266. The pivot rod258can extend between opposite sides270,274of the flow path234(or opposing portions of the inner surface250), and can be perpendicular to the central axis254. The pivot rod258can be centered in the main body210such that the pivot rod258intersects the central axis254. The pivot rod258can be pivotally mounted to the main body210for rotation within the flow path234about a pivot axis278. The pivot axis278can be perpendicular to the central axis254and can intersect the central axis254.

The biasing member218can rotationally bias the restricting element214toward a first rotational position A, shown inFIG. 3. The biasing member218can be a torsional spring having a first end282coupled to the main body210and a second end286coupled to the pivot rod258. The pivot aperture242can extend through one of the sides270,274of the main body210and can be coaxial with the pivot axis278. In the example provided, an end290of the pivot rod258extends through the pivot aperture242beyond the exterior230of the main body210, and the first end282of the biasing member218is mounted to the exterior230of the main body210. It is understood that the biasing member218can alternatively be located within the main body210and the pivot aperture242need not extend fully through the main body210to the exterior230. The restricting plate262and tab266can be non-rotatably, or fixedly coupled to the pivot rod258for rotation therewith.

With specific reference toFIG. 3, the flow restrictor70is shown with the restricting element214in the first rotational position A. The flow of the coolant fluid is generally indicated by arrows294. In the first position A the restricting plate262can extend from the pivot rod258toward the upstream end222, substantially parallel to the central axis254. In the example provided, the restricting plate262is generally semi-circular in shape, although any other suitable shape can be used, such as an elliptical, rectangular, or irregular shape, for example. In the example provided, the restricting plate262extends a length substantially equal to the radius of the flow path234. However, the restricting plate262can be longer or shorter than the radius of the flow path234.

The tab266can extend from the pivot rod258at an attack angle298relative to the restricting plate262. The attack angle298can be greater than zero degrees and less than one hundred and eighty degrees, for example. The attack angle298can also be between 180° and 360° relative to the restricting plate262. In the example provided, the tab266has a generally rectangular shape, although any other suitable shapes can be used, such as an elliptical, semi-circular, or irregular shape, for example.

In the example provided, the tab266is spaced apart from the sides270,274of the flow path234, such that the coolant fluid can flow around the sides of the tab266, between the tab and the flow path234. However, the tab266can alternatively extend the entire width of the flow path234, from side270to side274. The tab266can have a significantly smaller surface area than the restricting plate262, such that in the first position A, the coolant fluid is free to flow through the flow path234with little restriction, and the flow is only restricted by the width of the pivot rod258and the relatively small surface area of the tab266.

The biasing member218provides an opening torque302on the pivot rod258to bias the restricting element214toward the first rotational position A. The dynamic fluid pressures of the coolant fluid acting on the tab266create a closing torque306on the pivot rod258. When the flow of the coolant fluid is less than a predetermined flow rate, the closing torque306is insufficient to overcome the opening torque302of the biasing member218. Thus, with the exception of minor fluctuations, or deviations, the restricting element214is held generally in the first position A when the coolant fluid flows through the flow path234at a flow rate less than the predetermined flow rate.

With specific reference toFIG. 4, the flow restrictor70is shown in a second rotational position B. In the second rotational position, the flow of the coolant fluid is generally indicated by arrows310. When the flow rate of the coolant fluid exceeds the predetermined flow rate, the closing torque306overcomes the opening torque302provided by the biasing member218. Once the closing torque306is greater than the opening torque302, the pivot rod258begins to rotate about the pivot axis278. Rotation of the pivot rod258causes rotation of the restricting plate262off of central axis254and into an intermediate position (not shown) between the first position A and the second position B which the restricting plate262is at an angle314relative to the central axis254, and thus also relative to the flow310of the coolant fluid. When in the intermediate position, the angle314is greater than zero degrees and less than ninety degrees. As the angle314increases, the dynamic fluid pressure of the coolant fluid acting on the restricting plate262sharply increases, further increasing the closing torque306, and causing the pivot rod258to rotate into the second rotational position B. As the pivot rod258rotates, and the angle314increases, the restricting plate262rotates into the flow path234to block, or restrict the flow310of the coolant fluid without fully blocking all of the flow310through the flow path234. In the second rotational position B, the coolant fluid can be generally free to flow through the portion of the flow path234not blocked by the restricting plate262. While the example provided shows the restricting plate262blocking half of the flow path234, the restricting plate262can be configured to allow some flow through that half, such as through apertures (not shown) in the restricting plate262, or where the restricting plate262has a radius less than the radius of the flow path234, for example.

The stop element238can have a stop body318configured to engage the restricting element214when the restricting element214is in the second rotational position B to prevent the restricting element214from rotating further due to the closing torque306. In the example provided, the stop body318is coupled to the main body210within the flow path234, and extends from the main body210, radially inward toward the central axis254to engage the restricting plate262. The stop body318can alternatively, or additionally, be configured to engage the tab266or pivot rod258to prevent the closing torque306from rotating the restricting element214past the second rotational position B. It is understood that the stop body318can alternatively be coupled to the main body210in other locations, such as within the pivot aperture242, or on the exterior230of the main body210, to engage the pivot rod258. Although the example illustrated shows angle314between the restricting plate262and the central axis254at the second rotational position B, as being ninety degrees, the stop element238can be positioned to stop rotation of the restricting element214such that the angle314is less than ninety degrees, in order to allow some flow around the restricting plate262.

With additional reference toFIG. 7, the relationship between flowrate of the coolant fluid and engine speed (RPM) is shown. The flowrate in the coolant system18without the flow restrictor70in the coolant circuit122is generally indicated by dashed line718. The flowrate718can generally be directly proportional to the engine speed, such that the flowrate increases steadily as engine speed increases. The flowrate of the coolant system18with the flow restrictor70is shown as solid line722. The flowrate722can be generally proportional to the engine speed until a predetermined flowrate726is reached. Once the predetermined flowrate726is reached, the restricting element214of the flow restrictor70moves to the second rotational position, as discussed above, to limit the flowrate722to the predetermined flowrate726. The predetermined flowrate726can be a flowrate such that erosion within certain components of the coolant circuit122is minimized, such as the tubes82of the heat exchanger54for example.

With reference toFIGS. 5 and 6, the flow restrictor70is shown having a restricting element510of another configuration in a first rotational position C (FIG. 5) and a second rotational position D (FIG. 6). Restricting element510is similar to restricting element214, and includes a pivot rod514, a first restricting plate518, and a tab522, unlike the restricting element214, the restricting element510can further include a second restricting plate526. The tab522can extend from the pivot rod514at an attack angle530relative to the first restricting plate518, similar to attack angle298. The pivot rod514, first restricting plate518, and tab522can be substantially similar to pivot rod258, restricting plate262, and tab266, and their descriptions are incorporated herein by reference.

The second restricting plate526can be non-rotatably coupled to the pivot rod514for rotation therewith. The second restricting plate526can extend from the pivot rod514at a straight angle, or 180°, relative to the first restricting plate518. In the first position C, the second restricting plate526extends substantially parallel to the central axis254and toward the downstream end226of the main body210. In the example provided, the first restricting plate518and the second restricting plate526are substantially similar in size and shape, although other configurations can be used. In the example provided, the first restricting plate518and second restricting plate526each have a semi-circular shape with a radial length less than the radius of the flow path234, to allow flow around the first and second restricting plates518,526when in the second position D. However, the first restricting plate518and second restricting plate526can alternatively have a radial length substantially equal to the radius of the flow path234, while allowing flow through orifices (not shown) formed in the first and second restricting plates518,526, when in the second position D. The orifices can be designed to minimize or control turbulence downstream of the restricting plates518,526.

In the first position C, the flow of the coolant fluid is generally indicated by arrows534. The coolant fluid is free to flow through the flow path234with little restriction, and the flow is only restricted by the width of the pivot rod514and the relatively small surface area of the tab522. The biasing member218can be coupled to pivot rod514substantially similarly to pivot rod258, to provide an opening torque538on the pivot rod514to bias the pivot rod514toward the first position. The dynamic fluid pressures acting on the tab522create a closing torque542on the pivot rod514. When the flow of the coolant fluid is less than a predetermined flow rate, the closing torque542can be insufficient to overcome the opening torque538of the biasing member218. Thus, with the exception of minor fluctuations, or deviations, the restricting element510is held generally in the first position C when the coolant fluid flows through the flow path234at a flow rate less than the predetermined flow rate.

In the second position D, the flow of the coolant fluid is generally indicated by arrows546. When the flow rate of the coolant fluid exceeds the predetermined flow rate, the closing torque542is greater than the opening torque538provided by the biasing member218. Once the closing torque542is greater than the opening torque538, the pivot rod514begins to rotate. Rotation of the pivot rod514causes rotation of the first and second restriction plates518,526off of central axis254into an intermediate position (not shown) where the first restricting plate518is at an angle550relative to the central axis254, and thus relative to the flow546of the coolant fluid. When in the intermediate position, the angle550is greater than zero degrees and less than 90°.

As the angle550increases, the dynamic fluid pressure acting on the first restricting plate518sharply increases, further increasing the closing torque542. The dynamic fluid pressure acting on the second restricting plate526causes the opening torque538to increase. Since the second restricting plate526trails in the direction of the fluid flow546, and the first restricting plate518leads in the direction of the fluid flow546, the velocity of the coolant fluid between the first restricting plate518and the flow path234is relatively lower than the velocity of the coolant fluid between the second restricting plate526and the flow path. Thus, the dynamic fluid pressure acting on the first restricting plate518is higher than the dynamic fluid pressure acting on the second restricting plate526, which causes the closing torque542to increase greater than the opening torque538, and the pivot rod514is rotated into the second rotational position.

In the second position D, the dynamic forces acting on the first and second restricting plates518,526can balance with the opening torque538of the biasing member218. The amount of the opening torque538created by the biasing member218can be relatively minor compared to the closing torque542created by the balancing dynamic fluid pressures of the fluid acting on the first restricting plate518and the second restricting plate526when the first and second restricting plates518,526are in the second rotational position, or perpendicular to the flow path234, resulting in a quick transition between the first rotational position C and the second rotational position D.

As the pivot rod514rotates and the angle550increases, the first and second restricting plates518,526rotate into the flow path234to block or restrict the flow546of the coolant fluid, without fully blocking all of the flow546through the flow path234. In the example provided, the restricting plates518,526are illustrated in a vertical orientation, perpendicular to the central axis254, due to the relatively small force of the biasing member218relative to the dynamic fluid pressures on the first and second restricting plates518,526. It is understood that the exact orientation will depend on the surface areas of the first and second restricting plates518,526and the spring rate of the biasing member218. For example, the first and second restricting plates518,526may be balanced at a position where the angle550is less than 90° relative to the central axis254. Such a position can be designed to reduce turbulence downstream of the restricting plates518,526. In the second rotational position, the coolant fluid can be generally free to flow through the portion of the flow path234not blocked by the first and second restricting plates518,526. While the example provided shows the first and second restricting plates518,526blocking less than the full radius of the flow path234, the first and second restricting plates518,526can be configured to extend the full radius of the flow path234while allowing some flow through apertures (not shown) in either or both of the first and second restricting plates518,526.

The stop body318of the stop element238can engage the restricting element510when the restricting element510is in the second rotational position D to prevent the restricting element510from rotating further due to the closing torque542, similarly to the restricting element214. In the example provided, the stop body318is coupled to the main body210, and extends radially inward towards the central axis254to engage the first restricting plate518. The stop body318can also be configured to engage the pivot rod514, tab522, or second restricting plate526for example, as described above with respect to restricting element214. The operation of the coolant system18with restricting element214and restricting element510can be substantially similar with regard to flowrates and engine speed, as that discussed above with regard toFIG. 7.