Patent Application
20190101497
The present disclosure relates generally to a device system and method for measuring thermal properties of different types of shoes.
It is a common experience of persons wearing shoes in various environments that the overall perception of comfort of the shoe is significantly influenced by the thermal properties of that particular shoe as well as the size and style etc. When designing a shoe, the manufacturer can design different types of shoes with different thermal properties depending on the purpose of the shoe and the occasion for which the shoe will be worn.
Some shoes are designed to keep the feet warm while others may be designed to avoid trapping heat, particularly if they only partially enclose the foot. To compare various shoe designs, in addition to subjective data from actual human subjects, it is useful to objectively measure a shoe's thermal properties to evaluate the overall thermal comfort it provides.
Manikins having the shape of a human foot have been developed to allow manufacturers to objectively assess the thermal properties of various shoe designs.
It would be appreciated that as a human foot would be generally warmer compared to the surrounding temperature, manikins typically have heating elements to provide this elevated temperature. Typically, temperature measurements of a shoe on the manikin are taken using sensors in the region between the shoe and the foot manikin to quantitatively study the thermal characteristics of the shoe/foot manikin. Alternatively, an indirect way of measuring the thermal characteristics is by measuring the power provided to the heating element required to maintain the foot manikin surface at a predetermined temperature.
Typically, foot manikins are usually rigid and made of heat conductive metal for creating a uniform temperature over the foot manikin's surface. However, the rigidity of these foot manikins can lead to difficulties in fitting into different types of shoes, e.g. athletic shoes and boots. Further, the heavy weight of these prior art metal foot manikins means it can be somewhat difficult to conduct experiments.
Attempts have been made to more closely simulate the non-uniform variation of temperature on a human foot surface, which has slightly different temperatures at various regions of the foot. In U.S. Pat. No. 6,918,695 there is provided a foot manikin with thermally isolated regions allowing independent control on the temperature of each region. However, these thermally isolated regions are still different from the various temperatures that may be present on a human foot. Further, in this arrangement silicone diaphragms are required to thermally isolate the various regions on the foot manikin and independent electrical supplies have to be connected to each region, resulting in a cumbersome and difficult product to manufacture and use.
The present disclosure is therefore intended to obviate or at least alleviate at least one or more of the problems encountered in prior art.
According to a first aspect of the disclosure there is provided a device for measuring the thermal properties of different types of shoes comprising:
Preferably, the at least one heating element may be configured to simulate a non-uniform gradient temperature distribution of at least one corresponding surface portion of a human foot.
The heating element may comprise at least one or more resistive wires arranged in a predetermined configuration on a carrier element.
A non-uniform gradient temperature distribution may be created across the surface upon which the heating element is located by a corresponding non-uniform distribution of the resistive wires on the carrier element.
The at least one or more joints of the foot shaped member may be disposed at a similar location to a metatarsal phalangeal joint of a human foot.
The device may further comprise a flexible compressible layer for enclosing the foot shaped member and the heating element therein.
Optionally, the layer comprises silicone rubber.
The foot shaped member may comprise a thermoplastic material selected from the group comprising acrylonitrile butadiene styrene, polyethylene or polypropylene.
The device may further comprise a control unit regulating the power supplied to the heating element to maintain the predetermined elevated temperature distribution across said surface of the foot shaped member.
The device may further comprise an apparatus for directing an air current flow about the foot shaped member.
According to a second aspect of the disclosure there is provided a method for measuring the thermal properties of at least one shoe type, the method comprising
The at least one heating element may be configured to simulate a non-uniform gradient temperature distribution of at least one corresponding surface portion of a human foot.
The heating element may comprise at least one or more resistive wires arranged in a predetermined configuration on a carrier element
Optionally, a non-uniform gradient temperature distribution may be created across the surface upon which the heating element is located by a corresponding non-uniform distribution of the resistive wires on the carrier element.
The at least one or more joints of the foot shaped member may be disposed at a similar location to a metatarsal phalangeal joint of a human foot
According to a third aspect of the disclosure there is provided a system for measuring the thermal properties of different types of shoes comprising:
Optionally, the at least one heating element may be configured to simulate a non-uniform gradient temperature distribution of at least one corresponding surface portion of a human foot.
The non-uniform gradient temperature distribution may be created across the surface upon which the heating element is located by a corresponding non-uniform distribution of the resistive wires on the carrier element.
The at least one or more joints of the foot shaped member may be disposed at a similar location to a metatarsal phalangeal joint of a human foot.
The above features and advantages of the present disclosure will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings:
Various embodiments of the disclosure are discussed in detail below. While specific implementations are discussed, it should be understood that this is done for illustration purposes only. A person skilled in the relevant art will recognize that other components and configurations may be used without parting from the spirit and scope of the disclosure.
In one aspect, the present disclosure provides a foot manikin for measuring the thermal properties of various types of shoes. With reference to the figures, the foot manikin 10 comprises a foot shaped member 20 connected to a shin element 50 via an ankle joint 60. The foot shaped member depicted has a metatarsal phalangeal joint 30 connecting a toe portion 40 of the foot shaped member 20 with the rest of the foot shaped member 20. The ankle joint 60 allows pivotal movement of the foot shaped member 20 relative to the shin element 50 about an axis of the ankle joint 60 resembling the ability of the human foot to move around the ankle. Similarly, the metatarsal phalangeal joint 30 allows pivotal movement of the toe portion 40 relative to the rest of the foot shaped member 20 in a way that resembles toe movement about the metatarsal phalangeal joint of the human foot. The movability of the components of the foot manikin 10 relative to each other allows various types of shoes to be put on the foot manikin with ease, as is explained below.
It would be appreciated that the foot shaped member 20 may be made from any suitable thermoplastic material. The foot shaped member 20 may also be made from other materials depending on the desired properties of the foot member, including weight, rigidity and thermal conductivity. Preferably, the foot shaped member 20 may be made from Acrylonitrile Butadiene Styrene (ABS), Polyethylene (PE) or Polypropylene (PP). Preferably, the foot shaped member 20 is made with a flexible and compressible material for fitting of the foot shaped member 20 into shoes of different shapes and sizes.
Due to the capacity for relative movement between the different parts of the foot manikin 10 permitted by the ankle joint 60 and the metatarsal phalangeal joint 30, the foot manikin 10 can be easily fitted into different types of shoes in the same manner as the human foot may be fitted into various shoes. As an example, the foot manikin 10 may be fitted into a high heel shoe and an oxford shoe (as illustrated in
As discussed above, the foot shaped member 20 is preferably made with a flexible and compressible material. This would be advantageous where the foot manikin is to be fitted to a shoe having a shape different from that of the foot shaped member 20. For example, the women's flat shoe as shown in
Generally, the temperature of a human foot is warmer than its surrounding environment and therefore a heating means generating an elevated temperature at the surface of the foot shaped member 20 would be required. Referring to
The resistive wire 120 may take a variety of configurations in which the wire may be uniformly disposed (as illustrated in
As illustrated in
In an alternative embodiment shown in
It would be appreciated that the temperature distribution on the surface of a human foot may vary between different populations and is dependent on a number of factors such as the subject's age, gender, lifestyle and health. To cater for such difference, the resistive wire of the present disclosure may be arranged on or in the carrier element in a variety of non-uniform configurations. A higher density of resistive wire may be arranged at a position where a higher surface temperature is found on a corresponding position of the foot of a target population group, and vice versa. As such, an elevated temperature distribution on the surface of the foot shaped member 20 matching with the non-uniform gradient temperature distribution found on the foot of the target population group may be generated. In addition, as the non-uniform gradient temperature distribution is created by variations in the density of the resistive wire disposed on the carrier element, the non-uniform gradient temperature distribution so created does not suffer from any abrupt change of temperature between two proximal points as would be found in the case of a foot manikin divided into different temperature zones by insulating membranes.
In a further aspect of an exemplary embodiment, an external layer 200 as shown in
In an experiment for measuring the thermal properties of a specific shoe type selected from various different types of shoes, the available shoe to be tested is attached to the external layer 200 enclosing the foot manikin 10 and at least one of the heating elements 100a, 100b, 100c and 100d. Upon activation of the heating element(s), a predetermined elevated temperature distribution across a surface of the foot shaped member 20 is created. Temperature sensors, for example thermistor, thermocouple, resistive temperature detectors or infrared thermal detectors may be provided to monitor the temperature at a location proximal the surface of the foot shaped member 20. The thermal properties of the shoe being tested may be assessed by measuring the rate of heat lost from the surface of the foot shaped member 20, or the amount of power required to be supplied to the heating element(s) to maintain the predetermined elevated temperature distribution across the surface of the foot shaped member 20.
In a further embodiment, the system for measuring the thermal properties of a shoes selected from various different types of shoes may further include an apparatus 400 for directing an air current about the shoes. The relative movement between the air and the shoe is aimed to simulate a situation wherein a human foot wearing the shoe moves relative to its environment. This allows for the study on the thermal properties of the shoes when the person wearing the shoe is engaged in various kind of activities, e.g. walking, jogging or running. In a preferred embodiment, the system may further encompass an air flow sensor for measuring the speed of the air current at a location proximal to the shoe.
Thermal Properties of Shoes Tested on Human Feet
The thermal properties of a pair of closed toe slipper, a first pair of sports shoes and a second pair of sports shoes having a mesh-like surface were tested. The shoes were worn by a human subject and infrared thermal images of the shoes were taken in a walking test at 3 km/h after 30 minutes of walking.
The results for the pair of closed toe slipper and the first and second pair of sports shoes are shown respectively in
As seen from the infrared thermal images, the second pair of sports shoes has the best thermal conductivity, probably due to its mesh surface which assists in ventilation of the human feet. Shoes with high thermal conductivity are good at dissipating heat from the feet during exercise and keeping the foot cool in hot weather. On the other hand, the closed toe slipper is the best thermal insulator and would be useful for keep the foot warm in cold weather.
Temperature Distribution on Foot Manikin Assembly
A foot manikin assembly was constructed using the foot manikin 10, a variation of the heating element 100d (wherein the configuration of the resistive wire 120 is modified) and the external layer 200. The external layer 200 enclosed the foot manikin 10. The heating element, at least partially covering the surface of foot shaped member 20, was sandwiched between the external layer and the foot manikin 10.
A direct current power source of 10-20V was connected to the resistive wire 120 of the heating element. Infrared thermal images of the foot manikin assembly were taken 5 minutes after the power source was collected.
Thermal Properties of Shoes Tested With Foot Manikin Assembly
A sports shoe was fitted to the foot manikin assembly of Example 2. A direct current power source of 10-20V was connected to the resistive wire and infrared thermal images of the foot manikin assembly with the sports shoe were taken after 5 minutes. The infrared image is shown in
It would be appreciated that the original infrared thermal images referred to in the above examples were obtained in colour but are reproduced in the present disclosure in grayscale. While the original thermal image uses a scale from red to blue to represent different temperatures, the compression of such colour information into grayscale may result in some loss of information and as a result the gradient temperature transition in the grayscale figures may not be as clear as that in the original colour image. Nevertheless, a skilled person in the art would still appreciate that the device of the present disclosure is capable of generating a non-uniform elevated temperature distribution similar to that found on the surface of human foot.
The foot manikin of the present disclosure is significantly lighter than prior art manikins which enables easier manipulation. Furthermore, the foot manikin may be made from a flexible and compressible material and equipped with joints which functionally reproduce the ankle joint and metatarsal phalangeal joint of the human foot. Such design allows easy fitting of the foot manikin into various types of shoes, including sports shoe, high-heel shoe, oxford shoe and women's flat shoe.
Different forms of heating element may be provided for creating an elevated temperature on the surface of the foot manikin. The resistive wire disposed on the heating element may have various configurations and may be non-uniformly arranged on the heating element. The resistive wire may be configured to generate a gradient temperature distribution on the manikin surface that resembles the temperature distribution on the surface of a human foot.
The foot manikin allows for objective measurement of the thermal properties of a particular shoe type of the many shoe types available. With the interchangeable heating element and variable resistive wire configuration, simulation of the temperature distribution on the foot of a particular human subject selected from any age group and gender is possible, in a wide variety of different shoe types, without requiring different manikins or a variety of manikins.
Although the present disclosure has been explained by way of the examples described above, it should be understood to the ordinary skilled person in the art that the disclosure is not limited to the examples, but rather that various changes or modifications thereof are possible without departing from the disclosure.
