Abstract:
An apparatus for adding coolant to a cooling system of a motor vehicle includes a cap with a resilient sleeve that expands against the inside wall of a radiator filler neck to provide an air-tight connection. A valve attached to the cap controls the flow of air and coolant through the cap. A gauge on the cap indicates the pressure inside the radiator. A venturi assembly connected to the valve provides a source of vacuum for evacuating air from the cooling system. Thereafter, coolant is drawn through the cap by the vacuum created in the system.

Description:
The present application is a continuation of U.S. patent application Ser. No. 09/496,908, filed Feb. 2, 2000, now U.S. Pat. No. 6,153,193, the entire contents of which are hereby incorporated by reference and relied upon. 
     This application claims benefit of U.S. Provisional Patent Application No. 60/119,961 filed Feb. 12, 1999. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates to apparatus for testing and filling a cooling system of a motor vehicle with coolant. 
     Periodically, it is necessary to replace the coolant in the cooling system for a motor vehicle engine. For this purpose, a stopcock has been provided at the bottom of the radiator. In order to drain the system, the stopcock is opened and a cap at the top of the radiator is removed to allow air to enter the system braking a vacuum which would otherwise prevent the flow of old spent coolant through the stopcock. 
     Years ago a service technician draining the radiator simply allowed the spent coolant to flow to a floor drain in the garage from which it entered the municipal sewer system. With increased concerns about harming the environment, such dumping of coolant chemicals, which often contain heavy metals, into a sewer system has been prohibited. Now the service technician must place a pan beneath the stopcock in which to catch the coolant draining from the engine. The technician must then pour the coolant into a suitable container for proper disposal according to environmental protection regulations. The recovered coolant alternatively may be delivered to a recycling center which removes the contaminants and sells the cleansed coolant. 
     After the spent coolant is removed from the motor vehicle, the cooling system has to be filled with new coolant. This is accomplished by closing the stopcock and pouring the new coolant into the filler neck at the top of the engine that was opened by removal of the radiator cap. When the mechanic is working on the cooling system, often the drained coolant is placed back into the system, if the coolant is relatively fresh and uncontaminated. 
     Simply pouring the coolant into the filler opening is relatively time consuming and prone to coolant being spilled onto the floor of the garage. In addition, this process may not completely fill the cooling system with new coolant, as air which entered during the draining stage becomes trapped with in cavities in upper sections of the engine during refilling. Therefore, the engine often has to be operated for a period of time to flush the air into the upper part of the radiator from which the air can be replaced later with more coolant added to the system. 
     SUMMARY OF THE INVENTION 
     The present invention provides an apparatus for rapidly filling a motor vehicle cooling system with coolant. 
     That apparatus includes a service cap for attachment to the filler neck of the radiator. The service cap comprises a body, a collar, a resilient sleeve and a compression tube. The body has a passage there through and has external threads on an exterior surface. The collar is threaded onto the external threads of the body and has a first aperture. The resilient sleeve abuts the collar and has a second aperture. A head at one end of the compression tube abuts the sleeve with the compression tube extending through the first and second apertures. Another end of the compression tube is secured in the passage of the body. Movement of the collar on the threads of the body draws the compression tube through the collar and compresses the sleeve against the collar. This action produces outward expansion of the sleeve which seals the cap to the inside of the radiator filler neck. 
     In the preferred embodiment of the present invention, a valve is connected to the passage in the body to control flow of air and coolant through the passage. A pressure gauge also can be connected to the passage in the body. 
     The present cap is used to evacuate air from the cooling system by a vacuum source connected to the valve. The vacuum source can constitute a venturi assembly with a suction port connected to the valve, a fluid inlet and a fluid outlet. A muffler may be connected to the fluid outlet. After the evacuation of air, a source of coolant is connected to the valve with the coolant being drawn into the cooling system by the previously created vacuum. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 illustrates an engine coolant replacement apparatus according to the present invention; and 
     FIG. 2 is a cross sectional view through part of the apparatus in FIG.  1 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     With initial reference to FIG. 1, a motor vehicle has a cooling system which includes a radiator  20  with an upper radiator hose  22 . The radiator  20  contains a conventional coolant fluid made up of a mixture of water and additives, such as propylene glycol. Periodic maintenance requires that the coolant be drained from the motor vehicle and replaced with new coolant. For that purpose the radiator  20  has a neck  24  at the top through which coolant can be added. When the motor vehicle is operating the neck  24  of the radiator  20  is closed by an air tight cap (not shown). The standard radiator cap has a spring-loaded pressure relief valve that enables excessive coolant to flow to and from a recovery tank (not shown). 
     Periodic maintenance procedures employ an apparatus  30  for testing and filling the cooling system with the coolant. That apparatus comprises a service cap  32  that replaces the standard cap on the filler neck  24  of the radiator  20  during coolant replacement. Unlike the standard radiator cap, service cap  32  does not have a spring-loaded pressure relief valve. 
     With reference to FIG. 2 the service cap  32  has a cylindrical body  70  with a threaded central aperture  72  extending there through and a transverse aperture  74  extends from on side to the central aperture. The lower external circumferential surface of the body  70  is threaded to fit into a threaded collar  76 , which has an aperture  78  that is aligned with the central aperture  72 . A brass thrust washer  80  abuts the collar  76  and a cup-like, tubular rubber sleeve  82  abuts the washer  80 . A compression tube  84  with a longitudinal aperture  86  extends through the sleeve  82 , washer  80 , collar  76  and has one end  85  threaded into the central aperture  72  of body  70 . The compression tube  84  has a head  88  at the opposite end that contacts the end of the rubber sleeve  82  that is remote from the washer  80 . A small nipple  90  projects from the sleeve  82  around the head  88  of compression tube  84 . 
     When the service cap  32  is applied to the radiator  20 , the rubber sleeve  82  slides into the radiator filler neck  24 . While holding-the cap body  70  stationary, a service technician rotates the collar  76  to unthread the collar from the body. This action pulls the compression tube  84  through the collar  76  compressing the rubber sleeve  82  between the collar  76  and the compression tube head  88 . This causes the sleeve  82  to expand outward against the inner wall of the filler neck  24 . The resiliency of the sleeve  82  provides an air tight seal with the filler neck  24 . 
     Referring again to FIG. 1, the service cap  32  has a pressure gauge  34  attached thereto, which indicates the pressure within the radiator  20  when the service cap is sealed onto the neck  24 . A fitting is inserted into the transverse aperture  74  of the service cap  32  and a manual valve  36  is connected to the fitting thereby providing a closeable fluid passage into the radiator. A standard quick release female hose coupling  38  is attached to the end of the valve  36  that is remote from the service cap  32 . 
     Either a vacuum source  40  or a coolant supply hose  42  may be connected to the quick release female hose coupling  38 . The vacuum source  40  comprises a venturi assembly  44  having a suction pout  45 , a fluid inlet  46  and a fluid outlet  48 . A first quick release male hose coupling  49  is connected to the venturi suction port  45  so that the vacuum source can be attached to the assembly on the radiator  20 . The fluid inlet  46  is coupled to a hose  50  from a compressed air supply, such as an air compressor and tank of the type commonly found in motor vehicle repair garages. A filter may be placed between the hose  50  and the venturi&#39;s fluid inlet  46  to remove any particles in the compressed air which could adversely affect the operation of the venturi. 
     The fluid outlet  48  of the venturi assembly  44  is connected to a sound deadening muffler  52 . The muffler  52  is surrounded by an enclosure  54  with an opening  58  at a remote end. During operation of the apparatus  30 , should any liquid coolant be draw through the venturi  44  and the muffler  52 , the enclosure  54  prevents a liquid stream from being sprayed into the environment of the apparatus. 
     The coolant supply hose  42  has a second quick release male hose coupling  60 . The other end of the coolant supply hose  42  is placed within a supply of coolant. For example as shown in FIG. 1, this end of the hose  42  is within a conventional drain pan  62  that was used to catch the coolant  64  which was drained from the radiator  20 . Alternatively, the remote end of the hose  42  could be placed into a container of new coolant. 
     The old coolant is removed from the radiator  20  by conventional methods. For example, a stopcock (not shown) at the bottom of the radiator  20  is opened and the standard radiator cap is removed from the radiator filler neck  24  to allow air to enter the system braking a vacuum which would otherwise prevent the flow of old spent coolant through the stopcock. After all of the coolant has drained from the cooling system, the stopcock is closed. 
     Then the service cap  32  is tightened onto the filler neck  24  and the vacuum source is attached to the female hose coupling  38  The valve  36  is opened and the air supply hose is connected to a source of compressed air  50 . The air flows through the venturi assembly  44  from the fluid inlet  46  to the fluid outlet  48 . That air flow creates a negative pressure at the suction port  45 . That negative pressure draws air from the cooling system through the service cap  32 , valve  36  and couplings  38  and  49 . Eventually substantially all of the air is evacuated from the cooling system as indicated by the pressure reading on gauge  34 . At that time the valve  36  is closed. 
     The technician then monitors the pressure gauge  34  to observe whether the pressure changes during a period of a few minutes. If the cooling system is properly sealed, the pressure should not change, that is the vacuum produced by the suction from the venturi assembly  40  should be maintained. When that occurs the technician knows that the repairs resulted in a properly sealed cooling system. 
     Then the vacuum source  40  is removed from the female coupling  38  and the coolant supply hose  42  is attached in its place. With the other end of the supply hose  42  submerged in the coolant  64 , the valve  36  is opened. The partial vacuum within the radiator  20  and the rest of the cooling system draws the coolant  64  into the radiator. The technican ensures that there is more coolant  64  in the pan  62  than is needed to completely fill the cooling system. Eventually the technician will observe that additional coolant is not being drawn from the pan  62  which indicates that the cooling system is full. Because substantially all the air was removed from the cooling system before adding the coolant, there were no air pockets that could otherwise prevent the coolant from filling the system completely. 
     At this time the service cap  32  can be removed from the filler neck  24  of the radiator  20  and the standard cap attached thereto completing the filling process.