Patent Grant
7455199
The present invention relates to a frozen aerated product in a container and valves for dispensing such. The present invention more particularly relates to products commonly referred to as aerosols.
The availability of aerosol creams and toppings has led to their widespread use in customising desserts and beverages. Ice cream and similar frozen aerated products are often used as alternatives to whipped creams and toppings. The lack of such a product in an aerosol form, however, has meant that it is not possible to apply frozen products in such a controlled and convenient manner as whipped creams and thus limits their versatility. In addition, there has long been a need to provide soft-serve ice cream, a popular out-of-home dessert, in a form where it may be dispensed at home directly on removal from the freezer.
Aerosol systems for dispensing frozen aerated products have been proposed in the past. WO 03/096821 discloses such a system wherein the frozen aerated product is provided in a container, the container having at least two compartments and the frozen aerated product containing freezing point depressants in an amount between 20% and 40% w/w and having a number average molecular weight <M>n dependant on the fat level in the frozen aerated product. The container may be provided with a valve having an N value (ratio of the flow rate of a Newtonian fluid and the viscosity to the pressure drop across the valve) of between 5×10^(−11) m3 and 1×10^(−7) m3. Furthermore, embodiments are described with flow rates up to 4.7 g s−1 at −18° C.
Such technology allows for a frozen aerated product that may be dispensed from an aerosol can at the temperature of a domestic freezer (−18 to −22° C.) and represents a significant improvement over prior technologies. We have found, however, that there exists a need for further improvements in aerosol systems for dispensing frozen aerated products. In particular, the rate at which product is dispensed with the existing technology requires the user to hold the valve open for a considerable length of time. In addition, if conventional aerosol valves are used then the actuation force is found to be undesirably high for one-fingered actuation. Thus the products may not be applied to all of the applications for which aerosol whipped creams and toppings are used.
There is thus a need for an improved aerosol system for dispensing aerated products in a convenient manner at a temperature of a domestic freezer.
It has been found that it is possible to achieve such a goal by providing a frozen aerated product in a container equipped with a valve with a flow rate in a specific range. Furthermore, by careful design of the valve it has been found possible to provide valves suitable for dispensing viscous products from aerosol cans at high rates but which have low opening and actuating forces.
Tests and Definitions
Pressure
In the description ‘barg’ means ‘bar gauge’ (i.e., relative to 1 atm) and the pressure was measured at a temperature of −10° C.
Flow Rate
The flow rate of a valve arranged to dispense a frozen aerated product from a container is defined as the mass flow rate at which the frozen aerated product, having a temperature of −18° C., is discharged through the fully open valve to atmospheric pressure.
The flow rate is determined as follows.
Four specimens of a frozen aerated product in a container equipped with a valve and actuator are tempered at −18° C. for 24 hours. The actuator is designed to avoid any restriction of the flow of product following exiting from the valve such that any measurement of flow rate is a true measurement of flow through the valve alone. Each specimen is then taken from the −18° C. store, around 10 g of product dispensed through the valve and actuator and then the specimen returned to the −18° C. store. This pre-test dispensing ensures that the valve and actuator are charged fully with product while the small volume dispensed ensures that the pressure in the container is reduced only by a negligible amount. The cans are stored for a further 24 hours at −18° C. prior to testing.
For testing, a can is removed from the −18° C. store and the valve immediately actuated for a total of 10 s. This actuation is such that the valve is open to its full extent. The product dispensed during this actuation is collected and weighed. The flow rate for a specimen is then calculated by dividing the mass collected by 10 s. The process is then repeated for the other three specimens. The flow rate of the valve is taken to be the mean of the flow rate of the four specimens and the uncertainties quoted are the corresponding 95% confidence intervals.
Definition of Constriction
A constriction is defined as channel or orifice through which a product dispensed through a valve must pass. The cross-sectional area of such a constriction is the area of the channel or orifice, in a plane normal to the direction of flow of the product through the constriction during dispensing.
Opening Force
The opening force of a valve arranged to dispense a frozen aerated product from a container is defined as the minimum force that can be applied directly to the valve in order to open the valve to its full extent at a rate of 100 mm min−1, wherein the frozen aerated product has a temperature of −22° C.
The opening force is determined as follows.
Four specimens of a frozen aerated product in a container equipped with a valve (but not an actuator) are tested. The specimens are tempered at −22° C. for 24 hours prior to testing.
For testing, a can is removed from the −22° C. store and immediately secured in a cradle located in the environmental chamber of an Instron™ Universal Testing Machine. The cradle is designed to ensure that the container is static during testing and that the valve is located such that lowering or raising of the cross-head of the Instron™ opens the valve. The environmental chamber is supplied with liquid nitrogen and held at a constant temperature of −22° C. The cross-head is designed to allow full actuation without restricting the flow of product out of the valve. The cross-head is moved until it is around 0.5 mm away from touching the valve stem (or other valve member arranged to open the valve on application of a force) and the force meter on the testing machine is zeroed. The cross-head is then moved at a rate of 100 mm min−1 until the valve is opened to its full extent, the force applied being recorded every 0.1 s−1. The opening force for the specimen is taken to be the maximum force applied during the test. The process is then repeated for the other three specimens. The opening force of the valve is taken to be the mean of the opening force of the four specimens and the uncertainties quoted are the corresponding 95% confidence intervals.
Actuation Force
The actuation force of an actuating member provided to a valve arranged to dispense a frozen aerated product from a container is defined as the minimum force that can be applied directly to the actuating member in order to open the valve to its full extent when the member is moved at a rate of 100 mm min−1, wherein the frozen aerated product has a temperature of −22° C.
The actuation force is determined in an identical manner to that described for determining the opening force with two exceptions. Firstly, the valves are equipped with actuators. Secondly, the cross-head used is a simple cylinder and rather than acting directly on the valve stem (or other valve member arranged to open the valve on application of a force), the cross-head is moved onto the actuator during the test in order to mimic the action of the finger of a user when dispensing the product.
Average Molecular Weight
The average molecular weight for a mixture of freezing point depressants (fdps) is defined by the number average molecular weight <M>n (equation 1). Where wi is the mass of species i, Mi is the molar mass of species i and Ni is the number of moles of species i of molar mass Mi.
Freezing Point Depressants
Freezing point depressants (fpds) as defined in this invention consist in:
Overrun is defined by the following equation
It is measured at atmospheric pressure.
Definition of R Value
For a valve arranged to dispense a pressurised product, which is opened by the application of an opening force to one or other of a valve stem and a first member, a parameter R is defined by the following equation:
R=Am/Ab.
Wherein Ab is the maximum area of a cross-section of the stem bore in a plane normal to the direction of flow of the product during dispensing and Am is the area of an orthographic projection on to a plane normal to the direction of the opening force of those solid portions, on which with the valve in a closed position the pressure of the product acts in a direction opposite to the direction of the opening force, of the one or other of the valve stem and the first member to which the opening force is applied.
It is a first object of the present invention to provide a frozen aerated product in a container, the product being under a pressure of between 4 and 18 barg, the container being provided with a valve; characterised in that the valve has a flow rate of above 6 g s−1, preferably between 10 and 30 g s−1. Such a system is found to be particularly convenient to use directly from a domestic deep freeze, especially in applications normally reserved for aerosol whipped creams and toppings, such as the customisation of beverages and desserts. It also provides a versatile way of delivering individual portions of soft-serve ice cream at home directly on removal from the freezer.
Preferably the valve comprises a constriction having a cross-sectional area of less than 200 mm2, preferably less than 150 mm2. Preferably also the cross-sectional area is greater than 30 mm2. A valve having such a constriction is advantageous as, if the flow of a product through a valve is unconstrained then for a given mass flow rate of product, the linear velocity at which the product is dispensed will be lower than that desirable for applications such as customisation of desserts and beverages.
Preferably the valve has an opening force of less than 300 N, more preferably between 20 and 200 N. Preferably also, the valve is provided with an actuating member having an actuation force of less than 50 N, preferably between 20 to 35 N. We have determined that the use of valves and actuating members which have low opening and actuation forces respectively, allows for more versatile dispensing of frozen aerated products by affording the ability of the user to actuate the valve with a single hand or even a single finger.
In a preferred embodiment the container has at least two compartments (A) and (B), the compartments being gastightly separated from each other by an at least partially movable wall, compartment (A) containing a propellant, compartment (B) containing the frozen aerated product and compartment (B) being provided with the valve. Such a two-compartment system ensures that the product is always adjacent to the valve. This is desirable as the extremely viscous nature of frozen aerated products means that inversion of the container does not overcome the yield stress of the product and the product does not flow to the valve. Also dip tubes are to be avoided as the requirement for the product to flow through a long, narrow tube severely reduces the flow rate of the product.
In another preferred embodiment the frozen aerated product contains freezing point depressants in an amount between 20% and 40% w/w, preferably above 25%, and between 0% and 15% fat, preferably between 2% and 12%, the freezing point depressants having a number average molecular weight <M>n following the following condition:
<M>n=<(330−8*FAT) g mol−1
wherein FAT is the fat level in percent by weight of the product. Frozen aerated products with such a composition are found to be soft and extrudable even at the temperature of a domestic deep freezer.
In a particularly preferred embodiment the valve comprises: a valve stem having one or more apertures therein, the valve stem having a product outlet, a bore extending from the product outlet to the apertures, and a longitudinal axis; a first member having one or more apertures therein; and a resiliently biasable second member; one or other of the valve stem and the first member being slidably and coaxially mountable on or in the other of the valve stem and the first member; the valve stem and the first member being arranged such that on application of an opening force on one or other of the valve stem and the first member, the valve stem and the first member slide relative to each other in a direction parallel to the longitudinal axis of the stem and one or more of the apertures in the first member are brought into fluid communication with one or more of the apertures in the valve stem, the second member being arranged to force the apertures in the first member and the valve stem out of fluid communication when the opening force is released; characterised in that the ratio R is less than 2.0, preferably less than 1.1, more preferably R is less than 0.1. Preferably also, the second member comprises one or more springs.
A survey of known aerosol valves has shown that the ratio R is always much greater than 2. For example, for the valves described in FIG. 4 of U.S. Pat. No. 3,780,913, R is around 11.6; in the valves described in FIG. 1 of U.S. Pat. No. 6,149,077, R is around 10.6. Even in valves designed to allow for high discharge rates, such as the EM8 valve from Coster Aerosol Ltd (Stevenage, UK) which is similar in design to the valve shown in
In another preferred embodiment, the apertures in both the first member and the valve stem which are brought into fluid communication upon application of an opening force are located within the body of the container whilst in fluid communication. The advantage of requiring the apertures to be in fluid communication within the body of the container is that in the event of damage to the externally protruding parts of the valve either in use or in transit, the frozen aerated product should be retained within the container.
In a preferred embodiment, in the absence of the applied opening force, the second member is substantially free from contact with the frozen aerated product in the container. Preferably also, in the presence of the applied opening force, the second member is substantially free from contact with the frozen aerated product in the container. We have determined that in some instances, interaction of a frozen product with the second member can affect the ease with which a valve may be opened, especially when the product has a high viscosity such that it affects the ability of the second member to bias.
In another preferred embodiment the second member is located entirely within the body of the container. Location of the second member in such a way ensures that its performance is not hindered in the event of damage to the externally protruding parts of the valve either in use or in transit.
In yet another preferred embodiment, the valve is provided with an actuating member comprising: a first portion and a second portion, the second portion being hingedly attached to the first portion, the second portion being arranged to apply force to the one or other of the valve stem and the first member on application of a force thereto by a user. Preferably the second portion of the actuating member has a first end and a second end, the first end being attachable to a hinge on the first portion of the actuating member, and the second end being free, wherein the ratio of the distance from the hinge of the actuating member to the free end of the second portion is approximately three to eight times, preferably five to seven times, the distance from the hinge to a central longitudinal axis of the valve stem.
Such an actuating member is particularly advantageous owing to the multiplication of the actuation force resulting from the use of a lever allowing for valves to be used wherein the valve has a high opening force without inconveniencing the user by requiring a high actuation force. The length of the lever should be limited, however, to prevent the actuating member becoming too large and therefore impractical to use and store, especially in applications where the container is held in one hand and the valve actuated with the same hand.
It is a second object of the present invention to provide a valve comprising: a valve stem having one or more apertures therein, the valve stem having a product outlet, a bore extending from the product outlet to the apertures and a longitudinal axis; a first member having one or more apertures therein; and a resiliently biasable second member; one or other of the valve stem and the first member being slidably and coaxially mountable on or in the other of the valve stem and the first member; the valve stem and the first member being arranged such that on application of an opening force on one or other of the valve stem and the first member, the valve stem and the first member slide relative to each other in a direction parallel to the longitudinal axis of the valve stem and one or more of the apertures in the first member are brought into fluid communication with one or more of the apertures in the valve stem, the second member being arranged to force the apertures in the first member and the valve stem out of fluid communication when the opening force is released; characterised in that the ratio R is less than 2.0, preferably less than 1.1. Preferably also the second member comprises one or more springs.
Preferably, with the valve in a closed position, the one or other of the valve stem and the first member to which the opening force is applied is isolated from any pressure higher than atmospheric pressure acting in a direction opposite to that of the opening force, such that R is less than 0.1, more preferably less than 0.05 and optimally less than 0.01.
Because the valve stem and the first member slide relative to each other in a direction parallel to the longitudinal axis the valve provides for efficient filling through the valve, as the direction of flow of a product is then parallel with the movement of the valve during opening.
Preferably the stem has a base portion and the stem bore extends longitudinally through the base portion of the stem. The advantage of having a valve stem with the bore extending through the base portion is that the area of the base portion is minimised such that in situations where the opening force is applied to the stem and where the base portion is in contact with the internal pressure of the container, the area Am is kept to a minimum.
A further object of the present invention is to provide a valve for dispensing a product from a pressurised container, the valve comprising: a first piece which is fixedly attachable to the container; a second piece which is coaxially translatable on or in the first piece; a valve seat disposed between the first and second pieces and defining a closure, the valve seat being within the body of the container; and a bore extending from the seat to a product outlet; the valve being openable by coaxial translation of the second piece on or in the first piece in an opening direction; characterised in that the total surface area (Am) of the second piece on which the internal pressure of the container acts in a direction opposite to the opening direction is less than 30% of the cross-sectional area of the bore (Ab).
Because the valve is openable by coaxial translation, the valve provides for more efficient filling through the valve than rotatable valves, as the direction of flow of a product may be parallel with the movement of the valve during opening.
Preferably, the total surface area (Am) of the second piece on which the internal pressure of the container acts in a direction opposite to the opening direction is less than 10%, more preferably less than 5% and optimally less than 1% of the cross-sectional area of the bore (Ab) as the opening force is then substantially, if not completely, independent of the internal pressure of the container and/or the rheology of the product that the valve is arranged to dispense.
Furthermore, location of the valve seat within the container ensures that in the event of damage to the externally protruding parts of the valve, either in use or in transit, the product should be retained within the container
In a preferred embodiment the valve additionally comprises a resiliently biasable member (e.g. one or more springs) arranged to apply a closing force to the second piece. This arrangement allows for automatic closure of the valve, i.e. without the need for a user to translate the second piece back to a closed position following actuation. Furthermore, it is preferable that the resiliently biasable member is within the body of the container in order that its performance is not hindered in the event of damage to the externally protruding parts of the valve either in use or in transit.
Preferably also, the bore comprises one or more inlet orifices and extends from the inlet orifices to the product outlet. In a particularly preferred embodiment the inlet orifices of the bore are arranged such that the direction of product flow into the bore during dispensing is substantially perpendicular to the opening direction. By “substantially perpendicular” is meant that the direction of product flow is within 20°, preferably within 10° and more preferably within 5° of perpendicular. Such an arrangement allows for the design of the valve seat (and so the area Am) to be varied substantially, if not completely, independently of the flow rate of product into the bore.
It is also preferred that the bore is located within the second piece.
The valve is particularly suitable for dispensing the frozen aerated product in a container as described herein.
The present invention will now be described by way of example with reference to the accompanying drawings in which:
a is a sectioned view of a conventional aerosol valve;
b is a sectioned elevation of the valve stem of
c is an orthographic projection on to a plane normal to the direction of the opening force of the valve stem of
a is a sectioned view of a valve in the closed position in accordance with an embodiment of the invention;
b is a perspective view of the valve of
a is an elevation of a valve stem for use in a valve embodying the present invention;
b is a plan view of the stem of
c is a section through the valve stem of
d is a perspective view of the stem of
a is a plan view of the housing of a valve apparatus in accordance with an embodiment of the invention;
b is an elevation of the housing of
c is a sectioned view of the housing of
d is a perspective view of the housing of
a is a plan view of a component of the valve of
b is a sectioned elevation of the component of
c is a perspective view of the component of
a and 8b are elevations of an actuator for use in accordance with an embodiment of the invention;
c is a plan view of the actuator of
a is a sectioned elevation of an alternative valve in accordance with an embodiment of the invention;
b is a section through the stem of the valve of
c is an orthographic projection on to a plane normal to the direction of the opening force of the valve stem of
d is a perspective view of the valve stem of
The present invention will be further described with reference to the following preferred embodiments and examples.
a shows a conventional aerosol valve (2) having a valve stem (4) slidably and coaxially mounted in a valve housing (6) and fitted with a spring (8) to act on the stem (4). The housing (6) is mounted in a valve cup (10) which, in use, is attachable to an aerosol can (not shown).
When mounted in the valve housing (6), the spring (8) forces the end portion (14) of the stem (4) against the base of the stem gasket, which forms a valve seat (26), (17) so that the slits or apertures (16) in the wall of the tubular section (12) of the stem (4) are covered by the stem gasket (17) and any product and/or propellant in the can to which the valve is attached is prevented from escaping.
On application of an opening force the stem (4) is depressed to compress the spring (8) against its natural bias, the slits or apertures (16) in the stem move into the wider diameter section of the bore (19) extending through the housing so that the slits or apertures (16) are uncovered and product may travel up through the housing bore (19) and through the holes and apertures (16) in the stem and through the bore (15) and outlet (18) therein.
The housing (6) may be formed with a dip tube (22) to extend from the valve stem to the bottom of the can to which the valve is attached to allow for dispensing of the product without needing to invert the can.
The valve cup (10) is sealed onto a can in use with a gasket (24) positioned between the outer surface of the valve cup and outer surface of the rim of the bore into which the valve cup is located, to prevent product and propellant from leaking.
In addition to the pressure in the can and the viscosity of the product to be dispensed, the dimensions of the stem (4), such as the length of the stem (4), the diameter of the bore (15) of the stem (4), and the size of the holes or slits (16) determine the rate of flow of the product through the valve in the situation where the housing contains large slits or apertures such that product flow through the housing is not unduly restricted. The larger the area (Ab) of the cross-section of the bore (15) in a plane normal to the direction of flow, the greater the flow rate through the stem (4). The longer the bore (15), the lesser the flow rate. Therefore it is common practice in aerosol valves designed to allow for the dispensing of viscous products to maximise the cross-sectional area Ab.
In conventional aerosol valves such as that shown in
The contribution of the pressure of the product to the magnitude of the opening force is proportional to the area of an orthographic projection Am on to a plane normal to the direction of the opening force, of those solid portions of the stem (4) on which, with the valve in a closed position, the pressure inside of the can acts in a direction opposite to the direction of the opening force.
In manufacture, the propellant would be forced into the lower compartment (38) through a hole (39) in the base of the can (30) sealed by a rubber plug (not shown) and the product to be dispensed, would be forced through the valve (32) into the upper compartment (36) of the can (30).
The stem section (40) has a first substantially straight tubular section (56) which is connected to a second conical section (58). The second conical section (58) increases in diameter to a third section (59) which is substantially cylindrical and has a substantially constant diameter. The first section (56) has a product outlet (64) and a base portion (68). A plurality of apertures (66) are located in the first section (56). A longitudinally extending bore (65) extends from the product outlet (64) to the apertures (66). The third section (59) contains a groove (62) for receiving the second seal (54), which is preferably formed of rubber having a low glass transition temperature such that it is deformable at temperatures of a domestic deep freeze. The glass transition temperature of the rubber is preferably below −40° C., more preferably below −50° C.
The housing (42) comprises a first portion (70) and second portion (72). The first and second portions are comprised of a plurality of coaxial annular sections of varying outer diameters, the inner diameters being substantially constant. The first and second portions (70), (72) are spaced from each other axially and are coaxially aligned. The first and second portions (70), (72) are joined by a plurality of supporting columns (74), for example four columns. The columns (74) are essentially equally spaced in a circular configuration such that apertures or slits (75) are formed between the columns (74). The external surface of the first portion (70) contains a number of grooves (76) for receiving the first seal (48), which is preferably formed of rubber having a low glass transition. The external surface of the second portion (72) is essentially cylindrical at the base of the columns (74) and then increases in diameter in a stepped manner, terminating in a conical section (79) having a diameter which decreases to the base of the housing (80).
The first rubber seal (48) fits over the outside of the first portion (70) to provide a running seal to the tubular section (56) of the stem section (40). The outside of the seal (48) is shaped to seal with the valve cup (50) in which the valve system (32) is retained in use. The second rubber seal (54) provides a seal between the third section of the stem (59) and the second portion of the housing (72).
The base section (44) comprises two cylindrical sections (82), (84), the first cylindrical section (82) forming a disc. Extending around the outer periphery of the first cylindrical section (82) and projecting upwardly from the upper face thereof, is a short tubular section (83). The second section (84) of the base section (44) is coaxially aligned with the first section (82), the second section (84) having a diameter greater than the first section (82). The second section (84) joins the tubular section (83) just below the top edge of the tubular section (83) in such a manner as to form an annular cavity (91). The annular cavity (91) is shaped to receive the third rubber seal (49) which is preferably formed from a rubber with a low glass transition. The second section (84) has a number of equally spaced cut-out sections (86), for example four cut-out sections. Radially outwardly projecting retaining clips (90) extend from the upper peripheral rim of each of the plurality of cut-out sections (86). The tubular section (83) has an axial bore (92) extending therethrough, the bore being closed at one end by the upper surface of the first section (82). A short cylinder section (88) is located centrally on the upper surface of the first section (82).
The resilient member (46), which comprises for example one or more helical springs, is located in the bore (92) of the base section (44) and projects therethrough. The stem section (40) of the valve system (32) is positioned such that it sits coaxially over the base section (44) with the resilient member (46) projecting into the lower end of the stem section (40). The short cylinder section (88) is arranged to locate the one free end of the resilient member (46) centrally within the bore (92) of the tubular section (83). The other end of the resilient member (46) contacts a plurality of fingers (95) extending downwards from the second conical section (58) and/or the base portion (68) of the stem section (40).
The housing (42) sits over the first section (56) of the stem section (40) so that the stem section (40) projects through the bore in the first portion (70) of the housing (42), and the second portion (72) of the housing (42) fits into the annular cavity (91) of the base section (44) so that the conical section (79) formed at the base of the housing (42) clips under the retaining clips (90) of the base section (44). The third rubber seal (49) forms a seal between the base of the housing (80) and the base section (44). The lower portion of the stem section (40) slides inside the second portion of the housing (72) with the second rubber seal (54) forming a running seal between the stem (40) and the second portion of the housing (72). The second conical section (58) of the stem section (40) is pushed against the inner surface of the first seal (48) on the housing (42) by the resilient member (46).
As shown in
In operation, in the closed position, the apertures (66) in the stem (40) are sealed from the product compartment (36) of the container to which the valve assembly (32) is attached by means of the first seal (48), which forms a valve seat (48a). Applying an opening force to the stem (40) slides the stem longitudinally downwards towards the base section (44), causing compression of the resilient member (46) against its natural bias, and moving the second conical section (58) of the stem (40) away from the first seal (48) establishing a fluid communication through the apertures (66) in the stem (40) and the apertures (75) between the columns (74) in the housing (42) allowing the product in the can to pass through the apertures, into the bore (65) in the stem (40) and out of the stem outlet (64).
It will be appreciated that, with the valve in the closed position, the stem section (40) is isolated from the pressure in the can acting in a direction opposite to that of the opening force. Thus the R value for the valve shown in
Owing to the positioning of the second seal (54) and third seal (49) the resilient member (46) is isolated from the product and pressure in the container with the valve in a closed position. In addition, the base portion (68) of the stem section ensures that the resilient member (46) is substantially free from contact with the product at all times. It is, however, desirable that the base portion (68) contains one or more pin holes (69) to avoid problems associated with compression of air under the base portion (68) during opening of the valve. It has been found that two pinholes (69) that are around 0.2 mm in diameter are sufficient to eliminate problems associated with compression of air while being sufficiently small to keep the resilient member (46) substantially free from product in the presence of an applied opening force, i.e., during filling and use.
When the valve is open, pressurised product is in contact with the upper surfaces of the base portion (68) and the conical section (58) of the stem (40) and thus exerts a downward force on the stem (40). This can cause undesirable resistance to closure of the valve and so it is desirable to use a resilient member with a spring constant greater than that of resilient members used in conventional valves. Such a higher spring constant may be achieved, for example, by the use of two helical springs acting in parallel as shown in
In use, when attached to the aerosol can, an actuator is fitted over the valve assembly (32), as shown in
A nozzle (106) extends through the central aperture of the first section (100) and has a bore which is in fluid communication with the product outlet (64) of the stem (40) of the valve assembly (32). When the actuator is fitted over the valve of
In a preferred embodiment, the ratio of the distance from the hinge (103) to the edge of the lever (104) is approximately three to eight times the distance from the hinge (103) to the centre of the valve stem (40), such that the actuation force is one-third to one-eighth the opening force of the valve.
a through
The stem section (240) has a first substantially straight tubular section (256) which is connected to a second conical section (258). The second conical section (258) increases in diameter to a third section (259) which is substantially cylindrical and has a substantially constant diameter. Attached to the third section (259) is a substantially conical fourth section (262) whose diameter decreases such that the conical section tapers to the base portion (267) of the stem section (240). A longitudinally extending bore (265) extends from a product outlet (264) through the four sections (256), (258), (259), (262) and the end portion (267) of the stem section (240). A plurality of apertures (266) are located in the first tubular section (256).
The housing (242) comprises a first portion (270) and second portion (272). The first and second portions (270), (272) are joined by a plurality of supporting columns (274), for example four columns, extending between the two portions (270), (272). The columns (274) are essentially equally spaced in a circular configuration such that apertures or slits (275) are formed between the columns (274).
The first rubber seal (248) fits over the outside of the first portion (270) to provide a running seal to the tubular section (256) of the stem section (240). The outside of the seal (248) is shaped to seal with the valve cup (250) in which the valve system is retained in use.
A plurality of fingers (294) are located in a bore (292) of a central post in the base portion (244) and are arranged to retain the one free end of the resilient member (246). The cylindrical second seal (254) extends around the outer periphery of the central post on the base portion (244). The resilient member (246), which may be for example a helical spring, is located in the bore (292) of the base section (244) and projects therethrough. The stem section (240) is positioned such that it sits over the base section (244) with the resilient member (246) projecting into the lower end of the stem section (240). The lower portion of the stem section (240) slides over the seal (254) on the base section (244) such that the seal (254) and the central post of the base section (244) are located within the bore (265) of the stem section (240). The other end of the resilient member (246) contacts a plurality of fingers (295) extending into the bore (265) of the stem section (240) from the second conical section (258) and/or the third cylindrical section (259), towards the base of the stem section (240).
The housing (242) sits over the first section (256) of the stem section (240) so that the stem section (240) projects through the bore in the first portion (270) of the housing (242), and the second portion (272) of the housing (242) fits into the base section (244) so that the base of the housing (280) clips under the retaining clips (290) of the base section (244). The second conical section (258) of the stem section (240) is pushed against the inner surface of the seal (248) on the housing (242) by the resilient member (246).
In operation, in the closed position, the apertures (266) in the first tubular section (256) of the stem (240) are sealed from the pressurised product which the valve is arranged to dispense by means of the seal (248), which forms a valve seat (248a). Depressing the stem (240) towards the base section (244), causes compression of the resilient member (246) against its natural bias, and moves the second conical section (258) of the stem (240) away from the seal (248) establishing a fluid communication through the apertures (266) in the stem (240) and the apertures (275) between the columns (274) in the housing (242) allowing the product in the can to pass through the apertures, into the bore (265) in the stem (240) and out of the stem outlet (264).
c shows an orthographic projection of the stem (240) onto a plane normal to the direction of the opening force. The area Am is the area in the orthographic projection of those solid portions of the stem (240), namely the fourth conical section (262) and the base portion (267), on which with the valve in a closed position the pressure of the product to be dispensed acts in a direction opposite to the direction of the opening force. The ratio R for the valve shown in
A further alternative embodiment of a valve according to the invention is shown in
In use, the sheath (327) is held against the cap (350) by the spring (344) and the sheath (327) covers the aperture (324) in the stem (300) thereby preventing product from flowing through and out of the stem (300). A rubber o-ring (326) forms a seal between the stem (300) and sheath (327), thus providing a valve seat (326a). Depression of the lever (340) forces the sheath to slide down the stem (300) against the bias of the spring (344) so that the aperture (328) of the sheath (327) coincides with the outlet (324) in the stem (300) and product is able to flow therethrough. When the lever (340) is released, the spring (344) returns the sheath (327) to its rest position, closing the outlet (324) in the stem (300) and preventing further flow of product.
In the embodiment shown in
In a preferred embodiment of the valve shown in
Preferred examples of the dimensions for the various sections illustrated in
Stem Section
Housing
Base Section
It is thus considered that the above described valves may be used advantageously to dispense a frozen aerated product, such as a soft-serve ice cream, even in the typical temperature range of a domestic freezer, for example, between −18 to −22° C.
The embodiments of the valve systems shown in
Variations to the embodiments described above are possible which are within the scope of the invention. For example, the dimensions of the components of the valve assembly given above are preferred dimensions, but any one or more of these dimensions may be varied.
Furthermore, the valve systems illustrated in
Freezing point depressants in an amount of between 20% and 40% w/w, preferably above 25%, and between 0% and 15% fat, preferably between 2% and 12%, the freezing point depressants having a number average molecular weight <M>n following the following condition:
<M>n=<−8 FAT+330
wherein FAT is the fat level in percent by weight of the product.
The freezing point depressants may be made at least a level of 98% (w/w) of mono, di and oligosaccharides. In a preferred embodiment, the frozen aerated product contains less than 0.5% (w/w) glycerol, preferably less than 0.25% (w/w), even more preferably less than 0.1% (w/w).
Preferably, the frozen aerated product has an overrun of less than 150%, more preferably less than 140%, and preferably more than 80%. In an alternative preferred embodiment, the frozen aerated product has an overrun of more than 150%, and preferably more than 170%.
The average molecular weight is preferably below 250, more preferably below 230.
In one particularly preferred embodiment, the frozen aerated product is contained in a container of the type shown in
The types of container suitable for use in the present invention include those known as piston cans, bag-in-cans and bag-on-valve cans.
All concentrations are % (w/w).
Specialist materials were as follows:
The valves used in this example were similar to that shown in
The stem section (40) was injection moulded from POM (polyoxymethylene; Hostaform™ C27021 supplied by Ticona GmbH, Frankfurt, Germany). The housing (42) was injection moulded from PP (polypropylene) containing 20% glass fibre (Piolen® P G20 CA67 supplied by Pio Kunststoffe GmbH, Freiburg, Germany). The end section (44) was injection moulded from POM (Hostaform™ C9021). The first seal (48) was moulded from TPE (thermoplastic elstomer; Santoprene® 271-55EU supplied by Advanced Elastomer Systems, Akron, Ohio) having a glass transition temperature below −60° C. The second and third seals (54), (49) were formed from standard food grade silicone rubber.
The resilient member (46) comprised two helical steel springs acting in parallel as illustrated in
Container
Aluminum aerosol cans of the piston-type (Cebal, Barcelona, Spain) were used (686 ml brim-fill capacity, 18 bar buckle pressure). These cans had a wall-wiping piston (150 ml volume, giving a maximum product volume of 536 ml) and hole to accommodate a bottom-plug. Prior to use, an adhesive insulating label was applied to the body of each can. The labels used were of the expanded-polystyrene type [FoamTac II S2000 (Avery Dennison Group, Pasadena, Calif., USA)] and had a thickness of around 150 μm and a thermal conductivity of around 0.03 W m−1 K−1 at 273 K.
Process
Mixing
All ingredients except from the fat and emulsifiers were combined in an agitated heated mix tank. The fat was melted and emulsifiers added to the liquid fat prior to pouring into the mix tank. Once all of the ingredients were blended together, the mix was subjected to high shear mixing at a temperature of 65° C. for 2 minutes.
Homogenisation and Pasteurisation
The mix was passed through a homogeniser at 150 bar and 70° C. and then subjected to pasteurisation at 83° C. for 20 s before being rapidly cooled to 4° C. by passing through a plate heat exchanger.
Ageing
The mix was held at 4° C. for 5 hours in an agitated tank prior to freezing.
Gassing
Before attaching the valves, a positive air pressure was applied to the bottom hole of each can to ensure that the piston was pushed to the top. The valves were then clinched onto the cans in the usual manner to give a gas-tight seal. The cans were then bottom gassed to 1.8 barg with compressed air and simultaneously plugged using a Pamasol P593 X two-chamber propellant filler (DH Industries, Laindon, Essex, UK).
Freezing
The formulation was frozen using a typical ice cream freezer (scraped surface heat exchanger, SSHE) operating with an open dasher (series 80), a mix flow rate of 150 l/hour, an extrusion temperature of −9° C. and an overrun (at atmospheric pressure) of 135%.
Filling
From the freezer, the ice cream was fed directly into an aerosol-dosing chamber (DH Industries, Laindon, Essex, UK) at a line pressure of 10.5 barg. When full, the dosing chamber was then pressurised to 60 barg (by means of an intensifier) and a known volume of ice cream injected through the valve into the can. The volume injected was around 512 ml at the line pressure of 10.5 barg, giving a final can pressure of around 10 barg at −10° C. Each valve was then equipped with an actuator as illustrated in
Storage
Cans were stored at −25° C. for 1 week and then tempered at either −18° C. or −22° C. for 24 hours before use.
Final Product
The flow rate of the valve was 15.2±0.8 g s−1. The opening force of the valve was 155±12 N, which, when equipped with an actuator gives an actuation force of around 25 N. This system was easy to use with a single hand and was found to be ideal for applying the frozen aerated product to desserts and beverages directly on removal from a domestic deep freeze.
A frozen aerated product in a container was prepared with an identical formulation and in an identical manner to that described in Example 1 with the exception that a different valve was used.
The valves used in this example were similar to that shown in
| Number | Date | Country | Kind |
|---|---|---|---|
| 0404715.5 | Mar 2004 | GB | national |
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| Number | Date | Country | |
|---|---|---|---|
| 20050193744 A1 | Sep 2005 | US |
