Patent Description:
A hot water supply system of a heat pump type is known as a hot water generator. This conventional hot water supply system includes an outdoor unit (i.e., heat source unit) and a hydro unit (i.e., water/heat exchange unit). The hydro unit includes: a housing; an expansion tank that is provided inside the housing that alleviates pressure rise in piping due to hot water having risen in temperature; and a water heat exchanger that exchanges heat between water and a high-temperature refrigerant supplied from the heat source unit.

<CIT> discloses the features of the preamble of the independent claim. Further prior art is disclosed in <CIT>, <CIT>, <CIT>, <CIT> and <CIT>.

The hydro unit of the conventional hot water supply system generally includes a rectangular housing that has a front face, a rear face, a top face, a bottom face, and a pair of left and right side faces. The expansion tank provided in the housing is a cylindrical tank.

The rectangular tank can efficiently utilize the space inside the housing. However, the rectangular tank requires sufficient strength at the corners. Thus, the rectangular tank may be heavier and/or more expensive than the cylindrical tank that does not have a corner.

The cylindrical tank has a larger internal volume per unit weight than the rectangular tank. Thus, the cylindrical tank is cheaper and lighter than the rectangular tank having approximately the same internal volume. However, when the cylindrical tank is housed in a rectangular housing, a gap is generated between the cylindrical tank and the housing. That is, it is difficult for the cylindrical tank to efficiently utilize the space inside the housing as compared with the rectangular tank.

An object of the present invention is to provide a hot water generator that can efficiently accommodate a cylindrical expansion tank in a rectangular housing of its hydro unit.

A hot water generator according to the invention includes an outdoor unit that includes therein a compressor and a heat exchanger configured to exchange heat between a refrigerant and air, a hydro unit including a water heat exchanger that exchanges heat between water and the refrigerant flowing in from the outdoor unit. The hydro unit includes a rectangular housing that has a front face, a rear face, a top face, a bottom face, and a pair of side faces, and an expansion tank that has a cylindrical shape. The expansion tank has length dimension in a centerline direction larger than diameter dimension, and is accommodated in the housing with the centerline directed toward the pair of side faces.

Embodiments of a hot water generator according to the present invention will be described by referring to <FIG>. The same reference signs are given to identical or equivalent components in each figure.

<FIG> is a system configuration diagram of a hot water generator <NUM> according to one embodiment of the present invention.

As shown in <FIG>, the hot water generator <NUM> according to the present embodiment is a heat pump type. The hot water generator <NUM> includes: an outdoor unit <NUM> that is a heat source unit configured to exchange heat between outdoor air and a refrigerant; a hydro unit <NUM> (i.e., water/heat exchange unit) that exchanges heat between the refrigerant and water supplied from the outside of the generator; a remote controller <NUM> that accepts operations by a user as an input device; and a controller <NUM> that controls the outdoor unit <NUM> and the hydro unit <NUM> on the basis of the operations inputted to the remote controller <NUM>.

The hot water generator <NUM> circulates the refrigerant between the outdoor unit <NUM> and the hydro unit <NUM>, and heats water by exchanging heat between the refrigerant and water in a water heat exchanger <NUM> in the hydro unit <NUM> so as to supply hot water at the first temperature (for example, <NUM> degrees Celsius) to the outside of the generator. The hot water at the first temperature is returned to the hydro unit <NUM> through an external heating device (not shown) such as a floor heating system. In other words, water circulates between the hydro unit <NUM> and the external heat radiating device such as a heat radiator of the heating device.

In addition, the hot water generator <NUM> can supply high-temperature hot water at the second temperature (for example, about <NUM> degrees Celsius) to the outside of the generator by applying both of heat exchange between the refrigerant and water as well as heating with the use of a backup heater <NUM> described below. When only the heat exchange between the refrigerant and water is applied, though it depends on the type of refrigerant to be used, the maximum temperature is about <NUM> degrees Celsius in the case of using the R410A refrigerant. The hot water at the second temperature is stored in a hot water storage device outside the generator and then is used. The hot water stored in the hot water storage device is supplied to, for example, a washroom, a kitchen, and a bathroom. Normally, the outdoor unit <NUM> is installed outdoors and the hydro unit <NUM> is installed indoors. The outdoor unit <NUM> and the hydro unit <NUM> are interconnected by crossover pipes <NUM> and <NUM> of refrigerant piping <NUM> and a communication line (not shown). In the hot water generator <NUM> as described above, the water pipe is not laid outdoors, and thus, freezing of water in the water pipe does not occur at low temperature in winter.

The number of the included remote controller(s) <NUM> is one or more. For example, one remote controller <NUM> is installed in the hydro unit <NUM> and another remote controller (not shown) is installed indoors (e.g., on a wall surface).

The hot water generator <NUM> includes a refrigeration circuit <NUM>. The refrigeration circuit <NUM> transfers heat from a low temperature portion to a high temperature portion by using outdoor air as a heat source so as to heat water into hot water.

The refrigeration circuit <NUM> includes: a compressor <NUM>; an air heat exchanger <NUM> as an evaporator; an expansion valve <NUM>; the water heat exchanger <NUM> as a condenser; and refrigerant piping <NUM> that connects the compressor <NUM>, the air heat exchanger <NUM>, the expansion valve <NUM>, and the water heat exchanger <NUM> so as to circulate the refrigerant. The refrigeration circuit <NUM> transfers heat from the air heat exchanger <NUM> to the water heat exchanger <NUM> so as to heat the water into hot water in the water heat exchanger <NUM>.

The refrigeration circuit <NUM> further includes: a four-way valve <NUM> that sends the refrigerant having discharged from the compressor <NUM> to one of the air heat exchanger <NUM> and the water heat exchanger <NUM> and returns the refrigerant having passed through the other of the air heat exchanger <NUM> and the water heat exchanger <NUM> back to the compressor <NUM>; and an accumulator <NUM> disposed in the refrigerant piping <NUM> between the four-way valve <NUM> and the compressor <NUM>.

The water heat exchanger <NUM> is housed in the hydro unit <NUM>, and the rest of the other components of the refrigeration circuit <NUM> are housed in the outdoor unit <NUM>.

When the refrigeration circuit <NUM> heats water, the air heat exchanger <NUM> functions as an evaporator (also called a heat absorber) and the water heat exchanger <NUM> functions as a condenser (also called a radiator).

The compressor <NUM> compresses, boosts, and discharges the refrigerant. The compressor <NUM> can change the operating frequency by known inverter control. The amount of heat to be transferred to the high temperature portion increases by increasing the rotation speed of the compressor <NUM> and decreases by decreasing the rotation speed of the compressor <NUM>. In addition, the power consumption of the compressor <NUM> increases along with the increase in the rotation speed of the compressor <NUM>.

The expansion valve <NUM> is, for example, an electronic expansion valve (PMV: Pulse Motor Valve). The expansion valve <NUM> can adjust the valve opening degree. Although it is not shown, the expansion valve <NUM> includes: a valve body having a through hole; a needle that can advance and retreat with respect to the through hole; and a power source for advancing and retreating the needle, for example. When the through hole is closed with the needle, the expansion valve <NUM> stops, i.e., blocks the flow of the refrigerant in the refrigeration circuit <NUM>. At this time, the expansion valve <NUM> is in the closed state and the opening degree of the expansion valve <NUM> is the smallest. When the needle is farthest from the through hole, the flow rate of the refrigerant in the refrigeration circuit <NUM> is maximized and the opening degree of the expansion valve <NUM> is the largest.

The power source of the expansion valve <NUM> is, for example, a stepping motor. The rotation of the stepping motor causes the needle to move forward and backward, which changes the distance to the through hole and thereby changes the opening degree.

The refrigerant piping <NUM> connects the compressor <NUM>, the accumulator <NUM>, the four-way valve <NUM>, the air heat exchanger <NUM>, the expansion valve <NUM>, and the water heat exchanger <NUM>. The refrigerant piping <NUM> includes: a first refrigerant pipe 16a that connects the discharge side of the compressor <NUM> and the four-way valve <NUM>; a second refrigerant pipe 16b that connects the suction side of the compressor <NUM> and the four-way valve <NUM>; a third refrigerant pipe 16c that connects the four-way valve <NUM> and the water heat exchanger <NUM>; a fourth refrigerant pipe 16d that connects the air heat exchanger <NUM> and the water heat exchanger <NUM>; and a fifth refrigerant pipe 16e that connects the air heat exchanger <NUM> and the four-way valve <NUM>.

The accumulator <NUM> is provided on the second refrigerant pipe 16b. The expansion valve <NUM> is provided on the fourth refrigerant pipe 16d.

The four-way valve <NUM> switches the direction of the refrigerant flow in the refrigerant piping <NUM>. When the water is heated into hot water by the refrigeration circuit <NUM>, the four-way valve <NUM> circulates the refrigerant from the first refrigerant pipe 16a to the third refrigerant pipe 16c and circulates the refrigerant from the fifth refrigerant pipe 16e to the second refrigerant pipe 16b (refrigerant flow shown by the solid line in <FIG>).

When water is heated into hot water, the hot water generator <NUM> discharges the compressed high-temperature and high-pressure refrigerant from the compressor <NUM> and then sends the refrigerant to the water heat exchanger <NUM> via the four-way valve <NUM>. The water heat exchanger <NUM> exchanges heat between the water passing through the water heat exchanger <NUM> and the refrigerant passing through the water heat exchanger <NUM>. In this manner, the water is heated and the refrigerant is cooled so as to be in a high-pressure liquid state. That is, when water is heated into hot water, the water heat exchanger <NUM> functions as a radiator. The refrigerant having passed through the water heat exchanger <NUM> passes through the expansion valve <NUM> and is decompressed to become a low-pressure gas-liquid two-phase refrigerant, and then reaches the air heat exchanger <NUM>. The air heat exchanger <NUM> cools the outdoor air by exchanging heat between the outdoor air and the refrigerant passing through the air heat exchanger <NUM>. At this time, the air heat exchanger <NUM> functions as a heat absorber that evaporates the refrigerant into a gaseous state. The refrigerant having passed through the air heat exchanger <NUM> is sucked into the compressor <NUM>.

The refrigeration circuit <NUM> can perform defrosting operation by causing the four-way valve <NUM> to switch the direction of the refrigerant flow in the refrigerant piping <NUM>. When performing the defrosting operation, the hot water generator <NUM> inverts the four-way valve <NUM> such that the flow of the refrigerant is generated in the refrigeration circuit <NUM> in the direction opposite to the flow of the refrigerant heating up the water into hot water. In the case of the defrosting operation, the four-way valve <NUM> causes the refrigerant to circulate from the first refrigerant pipe 16a to the fifth refrigerant pipe 16e and from the third refrigerant pipe 16c to the second refrigerant pipe 16b (refrigerant flow indicated by the broken line in <FIG>). In the case of the defrosting operation, the air heat exchanger <NUM> functions as a condenser and the water heat exchanger <NUM> functions as an evaporator.

Further, the refrigeration circuit <NUM> may be dedicated to heating water without including the four-way valve <NUM>. In this case, the discharge side of the compressor <NUM> is connected to the water heat exchanger <NUM> via the refrigerant piping <NUM>, and the suction side of the compressor <NUM> is connected to the air heat exchanger <NUM> via the refrigerant piping <NUM>.

The hydro unit <NUM> includes: the water heat exchanger <NUM> of the refrigeration circuit <NUM>; an expansion tank <NUM> (i.e., expansion vessel); a water leading pipe <NUM> that leads the water before being heated from the outside of the hydro unit <NUM> to the water heat exchanger <NUM>; a hot-water leading pipe <NUM> that leads the hot water heated by the water heat exchanger <NUM> to the expansion tank <NUM>; a hot-water supplying pipe <NUM> that supplies the hot water heated by the water heat exchanger <NUM> to the outside of the hydro unit <NUM>; a backup heater <NUM> that is disposed in the hot-water supplying pipe <NUM> and heats the hot water to be sent from the expansion tank <NUM> to the outside of the hot-water supplying pipe <NUM> up to a higher temperature; and a pump <NUM> that is disposed in the hot-water supplying pipe <NUM> and sends the hot water from the expansion tank <NUM> to the outside of the hydro unit <NUM>.

The hydro unit <NUM> may be used for circulating hot water between the hydro unit <NUM> and a device outside the hydro unit <NUM> or may be used for heating water outside the hydro unit <NUM> into hot water and supplying the hot water to the outside of the hydro unit <NUM>. The device outside the hydro unit <NUM> is, for example, a heating device (not shown) or a hot water storage device (not shown) that heats water using the circulating hot water and stores the water heated by the hot water.

The hydro unit <NUM> further includes: refrigerant pipe connection joints <NUM> and <NUM> that connect the crossover pipes <NUM> and <NUM> of the refrigerant piping <NUM> to the refrigerant piping <NUM> in the hydro unit <NUM>; a water-leading-pipe connection joint <NUM> that connects a water pipe <NUM> outside the hydro unit <NUM> to the water leading pipe <NUM>; and a hot-water pipe connection joint <NUM> that connects a hot-water pipe <NUM> outside the hydro unit <NUM> to the hot-water supplying pipe <NUM>. These connection joints <NUM>, <NUM>, <NUM> and <NUM> are screw-in pipe joints.

The crossover pipes <NUM> and <NUM> of the refrigerant piping <NUM> allow the refrigerant to flow between the outdoor unit <NUM> and the hydro unit <NUM>. The crossover pipe <NUM> is part of the third refrigerant pipe 16c and is laid outside the outdoor unit <NUM> and outside the hydro unit <NUM>. The crossover pipe <NUM> is part of the fourth refrigerant pipe 16d and is laid outside the outdoor unit <NUM> and outside the hydro unit <NUM>. The portion provided in the hydro unit <NUM> as part of the third refrigerant pipe 16c for connecting the refrigerator pipe connection joint <NUM> to the water heat exchanger <NUM> is referred to as a first intra-hydro-unit refrigerant pipe <NUM>. The portion provided in the hydro unit <NUM> as part of the fourth refrigerant pipe 16d for connecting the refrigerant pipe connection joint <NUM> to the water heat exchanger <NUM> is referred to as a second intra-hydro-unit refrigerant pipe <NUM>.

The hot-water pipe <NUM> is a crossover pipe that connects the hydro unit <NUM> and the hot water supply place, and the water pipe <NUM> is a crossover pipe that connects the hydro unit <NUM> and the water supply place. In the case of the circulation type, the hot water supply place and the water supply place are connected.

The hot-water leading pipe <NUM> connects the upstream of the pump <NUM> and the downstream of the backup heater <NUM> in the hot-water supplying pipe <NUM> to the expansion tank <NUM>. The hot-water leading pipe <NUM> leads the warmed and expanded hot water in the hot-water supplying pipe <NUM> to the expansion tank <NUM>. The expansion tank <NUM> has a function of absorbing the expansion (increase in volume) of the warmed hot water.

The hot water, which is heated in the water heat exchanger <NUM> by the refrigerant circulating in the refrigeration circuit <NUM>, is sucked into the hot-water supplying pipe <NUM> by the driven pump <NUM> and then is supplied to the hot water supply place through the hot-water pipe <NUM> outside the hydro unit <NUM>.

<FIG> is a perspective view of the hydro unit <NUM> when viewed from the diagonally right front and from below.

<FIG> is an exploded perspective view of the hydro unit <NUM> when viewed from the diagonally right front and from above.

As shown in <FIG> and <FIG>, the hydro unit <NUM> of the hot water generator <NUM> according to the present embodiment includes a longitudinally elongated rectangular housing <NUM>.

The housing <NUM> has a front face 51f, a rear face 51r, a top face 51t, a bottom face 51b, and a pair of side faces <NUM>. The housing <NUM> includes: a front plate <NUM> that covers the front face 51f; a rear plate <NUM> that covers the rear face 51r, a top plate <NUM> that covers the top face 51t; a bottom plate <NUM> that covers the bottom face 51b; and a pair of side plates <NUM> and <NUM> that cover the respective side faces <NUM>.

The housing <NUM> accommodates the expansion tank <NUM>, the water leading pipe <NUM>, the hot-water leading pipe <NUM>, the hot-water supplying pipe <NUM>, the pump <NUM>, the water heat exchanger <NUM> of the refrigeration circuit <NUM>, the first intra-hydro-unit refrigerant pipe <NUM>, and the second intra-hydro-unit refrigerant pipe <NUM>.

The housing <NUM> further accommodates: a controller accommodation box <NUM> that houses the controller <NUM>; and a controller supporting plate <NUM> that supports the controller accommodation box <NUM> inside the housing <NUM>. The controller accommodation box <NUM> is a box that opens toward the front of the housing <NUM>. In the controller accommodation box <NUM>, a board on which the controller <NUM> is mounted is supported.

The front plate <NUM> has an operation window <NUM> for disposing the remote controller <NUM>. The back side of the front plate <NUM> is provided with a controller supporting plate <NUM> that supports the remote controller <NUM> disposed in the operation window <NUM>. The controller supporting plate <NUM> has a function of a lid that covers the controller accommodation box <NUM>.

The front plate <NUM>, the rear plate <NUM>, the top plate <NUM>, the bottom plate <NUM>, the side plates <NUM> and <NUM>, the controller accommodation box <NUM>, the controller supporting plate <NUM>, and the controller supporting plate <NUM> are processed sheet metal products.

The water leading pipe <NUM>, the hot-water leading pipe <NUM>, the hot-water supplying pipe <NUM>, the pump <NUM>, the water heat exchanger <NUM> of the refrigeration circuit <NUM>, the first intra-hydro-unit refrigerant pipe <NUM>, and the second intra-hydro-unit refrigerant pipe <NUM> are disposed in the space that is sandwiched between the rear plate <NUM> and the controller supporting plate <NUM>. The expansion tank <NUM> is disposed in the space that is above the controller supporting plate <NUM> and sandwiched between the front plate <NUM> and the rear plate <NUM>.

As shown in <FIG>, the rear plate <NUM> of the housing <NUM> in the hot water generator <NUM> according to the present embodiment supports the expansion tank <NUM> and the water heat exchanger <NUM> of the refrigeration circuit <NUM>.

The expansion tank <NUM> has a cylindrical shape in which the length L in the direction of the centerline C is larger in dimension than the diameter D. The expansion tank <NUM> is housed in the housing <NUM> such that the centerline C is oriented in the direction toward the pair of side faces <NUM>. In other words, the length L of the expansion tank <NUM> is smaller in dimension than the width of the housing <NUM>. Further, the diameter D of the expansion tank <NUM> is smaller in dimension than the height and the depth of the housing <NUM>. The expansion tank <NUM> is disposed at the uppermost part of the housing <NUM>. The expansion tank <NUM> includes a cylindrical body 31a and a pair of end plates 31b and 31c that close both ends of the body 31a. The expansion tank <NUM> is fixed to the rear plate <NUM> by a saddle-shaped tank fixing band <NUM> extending on the body 31a. The tank fixing band <NUM> fixes the expansion tank <NUM> to the rear plate <NUM> like a saddle band used for fixing pipes. That is, the tank fixing band <NUM> is bent along the body 31a from the upper part to the lower part of the body 31a so as to fix the expansion tank <NUM> to the rear plate <NUM> of the housing <NUM>.

The water leading pipe <NUM>, the hot-water leading pipe <NUM>, the hot-water supplying pipe <NUM>, the pump <NUM>, the water heat exchanger <NUM> of the refrigeration circuit <NUM>, the first intra-hydro-unit refrigerant pipe <NUM>, and the second intra-hydro-unit refrigerant pipe <NUM> are disposed below the expansion tank <NUM>.

The water heat exchanger <NUM> is disposed directly under the expansion tank <NUM> and near the side plate <NUM> on one of the left and right sides of the housing <NUM> (on the left side, in this case). The backup heater <NUM> is disposed directly under the expansion tank <NUM> and near the side plate <NUM> on the other of the left and right sides of the housing <NUM> (on the right side, in this case). The backup heater <NUM> is fixed to the rear plate <NUM>. Under the circumstances where the outside temperature is so extremely low that heating the water into hot water by the refrigeration circuit <NUM> is difficult, the backup heater <NUM> is used for assisting the heating of water and for further heating the hot water that is already heated by the refrigeration circuit <NUM> into hotter water.

The pump <NUM> is disposed below the expansion tank <NUM>, directly in front of the backup heater <NUM>, and on the bottom plate <NUM> of the housing <NUM>. Directly below the pump <NUM>, the hot-water pipe connection joint <NUM> is provided. The hot-water pipe connection joint <NUM> protrudes toward the outside of the housing <NUM>. The hot-water pipe connection joint <NUM> protrudes downward from the bottom plate <NUM> so as to be exposed to the outside of the housing <NUM>.

The water-leading-pipe connection joint <NUM> is provided behind the obliquely left side of the hot-water pipe connection joint <NUM>. The water leading pipe <NUM> connected to the water-leading-pipe connection joint <NUM> bends toward the water heat exchanger <NUM> at the portion that enters the back side of the housing <NUM> from the bottom plate <NUM> of the housing <NUM>, extends in the vicinity of the bottom plate <NUM> in parallel to the bottom plate <NUM>, and is connected to the back side of the lower end of the right side-face of the water heat exchanger <NUM>. The hot-water supplying pipe <NUM> is connected to the back side of the upper end of the right side-face of the water heat exchanger <NUM>. The hot-water supplying pipe <NUM> extends from the water heat exchanger <NUM> toward the side plate <NUM> of the housing <NUM>, bends at an intermediate position between the water heat exchanger <NUM> and the backup heater <NUM> toward the bottom plate <NUM> of the housing <NUM>, hangs directly downward so as to extend in parallel to the bottom plate <NUM> at a portion reaching the lower end of the backup heater <NUM>, and is connected to the lower end of the left side-face of the backup heater <NUM>. The hot-water leading pipe <NUM> branches from the hot-water supplying pipe <NUM> via a cross-shaped branch at the upper end of the front face of the backup heater <NUM>, rises toward the top face plate <NUM> of the housing <NUM>, reaches substantially the same height as the centerline C of the expansion tank <NUM>, and bypasses the front of the expansion tank <NUM> so as to be connected to the end plate 31b on the left side of the expansion tank <NUM>.

The hot-water supplying pipe <NUM> extends downward from the cross-shaped branch so as to reach the pump <NUM>. That is, the pump <NUM> is connected to the outlet end of the hot-water supplying pipe <NUM>.

The first intra-hydro-unit refrigerant pipe <NUM> and the second intra-hydro-unit refrigerant pipe <NUM> enter the housing <NUM> through a refrigerant-pipe insertion hole <NUM> provided on the bottom plate <NUM> of the housing <NUM>.

The first intra-hydro-unit refrigerant pipe <NUM> extends on the right side of the water heat exchanger <NUM> toward the expansion tank <NUM>, bends toward the water heat exchanger <NUM> near the front of the upper end of the right side-face of the water heat exchanger <NUM>, and is connected to the water heat exchanger <NUM>. The first intra-hydro-unit refrigerant pipe <NUM> rises and extends almost directly in front of the hanging portion of the hot-water supplying pipe <NUM>. The refrigerant pipe connection joint <NUM> is provided at the end of the first intra-hydro-unit refrigerant pipe <NUM> disposed outside the housing <NUM>.

The second intra-hydro-unit refrigerant pipe <NUM> rises in parallel to the first intra-hydro-unit refrigerant pipe <NUM> in the vicinity closer to the water heat exchanger <NUM> than the first intra-hydro-unit refrigerant pipe <NUM>, bends toward the water heat exchanger <NUM> near the front of the lower end of the right side-face of the water heat exchanger <NUM>, and is connected to the water heat exchanger <NUM>. The refrigerant pipe connection joint <NUM> is provided at the end of the second intra-hydro-unit refrigerant pipe <NUM> disposed outside the housing <NUM>.

Next, the fixing structure of the expansion tank <NUM> will be described.

<FIG> is a longitudinal cross-sectional view of the hot water generator according to the present embodiment.

As shown in <FIG> in addition to <FIG> and <FIG>, the expansion tank <NUM> of the hot water generator <NUM> according to the present embodiment includes at least one convex part <NUM> that protrudes outward in the radial direction of the cylindrical body 31a and extends in the circumferential direction of the body 31a.

The convex parts <NUM> annularly circle the body 31a and are connected in a row. The number of the convex parts <NUM> is two or more including the first convex part 81a and the second convex part 81b. The convex parts <NUM> are, for example, joint parts that join two members to form an integrated body 31a or holding parts that hold diaphragms (not shown) in the expansion tank <NUM> on the inner circumferential face of the body 31a. The plurality of convex parts 81a and 81b are separated from each other in the direction of the centerline of the expansion tank <NUM> and are arranged in parallel.

The convex parts <NUM> may be provided in the body 31a annularly and discretely (i.e., discontinuously or at intervals).

The tank fixing band <NUM> may be in a shape of hexagonal saddle as shown in <FIG>, may be in a shape of polygonal saddle such as triangular, rectangular, and pentagonal saddles, or may be in a shape of arc-shaped saddle. The hexagonal saddle-shaped tank fixing band <NUM> has: a first part 66a that is in contact with the top of the expansion tank <NUM> and is fixed to the rear plate <NUM>; a second part 66b that is continuous with the first part 66a and slopes down toward the front of the expansion tank <NUM> while partially contacting the expansion tank <NUM>; a third part 66c that is continuous with the second part 66b and is located in front of the expansion tank <NUM> while partially contacting the expansion tank <NUM>; a fourth part 66d that is continuous with the third part 66c and slopes down toward the bottom of the expansion tank <NUM> while partially contacting the expansion tank <NUM>; a fifth part 66e that is continuous with the fourth 66d and is fixed to the rear plate <NUM> so as to be in contact with the bottom of the expansion tank <NUM>.

The tank fixing band <NUM> has at least one hole <NUM> that is interdigitated with the convex part <NUM>. The respective holes <NUM> are provided at positions where the convex parts <NUM> can be fitted from one end to the other end of the tank fixing band <NUM>. The plurality of holes <NUM> are arranged and include: a first hole 82a into which the first convex part 81a is fitted; and a second hole 82b into which the second convex part 81b is fitted. The plurality of holes 82a and 82b are separated from each other in the band width direction of the tank fixing band <NUM> and are arranged in parallel.

In the polygonal saddle-shaped tank fixing band <NUM>, the holes <NUM> are preferably provided discretely (i.e., discontinuously or at intervals) so as to avoid the vertices as shown in <FIG>. In this case, the tank fixing band <NUM> can readily obtain sufficient strength for supporting the expansion tank <NUM>. In the hexagonal saddle-shaped tank fixing band <NUM>, the holes <NUM> are discretely provided from the first part 66a to the fifth part 66e of the tank fixing band <NUM> and are interrupted at the ridges connecting the respective parts 66a to 66e.

The rear plate <NUM> includes: a band fixing hole <NUM> provided above the expansion tank <NUM>; a band fastening hole <NUM> provided below the expansion tank <NUM>; and a pair of anti-rolling stoppers <NUM> that prevents the expansion tank <NUM> from rolling against the rear plate <NUM>.

The band fastening hole <NUM> is provided in the flange 53a for fixing the top plate <NUM> to the rear plate <NUM>.

The pair of anti-rolling stoppers <NUM> are disposed below the band fixing hole <NUM> and above the band fastening hole <NUM> and have a convex shape extending in a direction parallel to the longitudinal direction of the expansion tank <NUM>. The expansion tank <NUM> is in contact with the rear plate <NUM> at the portion sandwiched between the pair of anti-rolling stoppers <NUM>. It is preferred that the expansion tank <NUM> is also in contact with the pair of anti-rolling stoppers <NUM>.

The tank fixing band <NUM> has: a folded part 66f that is inserted into the band fixing hole <NUM> of the rear plate <NUM>; and a flange <NUM> that is fixed to the band fastening hole <NUM> by a fastening member <NUM>. The folded part 66f is provided at the upper end part of the tank fixing band <NUM>, i.e., at the root part of the first part 66a. The folded part 66f is a cut-up formed on the tank fixing band <NUM>, which is a processed sheet metal product, and is formed by bending a material of this sheet product. The flange <NUM> is provided at the lower end of the tank fixing band <NUM>, i.e., at the root part of the fifth part 66e.

In addition to or instead of the folded part 66f, a fastening member may be used for fixing the root part of the first part 66a of the tank fixing band <NUM>, which has the folded part 66f, to the flange 53a of the rear plate <NUM>.

As shown by the two-dot chain line in <FIG>, when the expansion tank <NUM> is housed in the housing <NUM> in such a manner that the centerline C of the cylindrical expansion tank <NUM> matches the up-and-down direction of the housing <NUM>, the height dimension of the housing <NUM> significantly increases.

The depth dimension of the housing <NUM> depends on the diameter dimension D of the expansion tank <NUM> and does not change substantially regardless of whether the accommodation state of the expansion tank <NUM> in the housing <NUM> is an upright state or a lying state. Since the width dimension of the housing <NUM> depends on the size and disposition of devices in the housing <NUM> excluding the expansion tank <NUM>, when the expansion tank <NUM> is housed in the housing <NUM> in the upright state, a large-capacity space in which no device is placed, i.e., so-called dead space is generated in the housing <NUM>. When the expansion tank <NUM> is housed in the housing <NUM> in the state of being laid down, the width dimension of the housing <NUM> can be effectively utilized as shown in <FIG>. That is, when the expansion tank <NUM> is accommodated in the housing <NUM> in the lying state, the height dimension of the housing <NUM> can be suppressed and the hydro unit <NUM> can be miniaturized. Further, when the expansion tank <NUM> is accommodated in the housing <NUM> in the lying state, the length L of the expansion tank <NUM> is extended to the extent that the expansion tank <NUM> fits within the width dimension of the housing <NUM>, and thus, the internal volume of the expansion tank <NUM> is expanded.

As described above, the hot water generator <NUM> according to the present embodiment includes the cylindrical expansion tank <NUM> that has the length L in the direction of the centerline C larger in dimension than the diameter D and is housed in the housing <NUM> with its centerline C directed toward the pair of side faces <NUM> of the housing <NUM>. Hence, the hot water generator <NUM> can accommodate the cylindrical expansion tank <NUM>, which is cheaper and lighter than a rectangular tank having almost the same internal volume, and can efficiently utilize the space in the housing <NUM>. As a result, the hydro unit <NUM> of the hot water generator <NUM> can be small and lightweight that provides a satisfactory appearance, high workability at the time of installation, and small occupation space in the installed state.

In addition, the hot water generator <NUM> according to the present embodiment includes the expansion tank <NUM> disposed in the uppermost part of the housing <NUM>. Thus, in the hot water generator <NUM>, the size of the hydro unit <NUM> can be reduced while the expansion tank <NUM> and other devices to be housed in the housing <NUM> can be efficiently disposed.

Further, the hot water generator <NUM> according to the present embodiment includes the tank fixing band <NUM> that has the holes <NUM> to be interdigitated with the convex parts <NUM> of the expansion tank <NUM> and fixes the expansion tank <NUM> to the rear plate <NUM> of the housing <NUM> by extending on the body 31a of the expansion tank <NUM> from above to below the body 31a. Hence, the hot water generator <NUM> can reliably fix the expansion tank <NUM> at a predetermined position and prevent the installation position of the expansion tank <NUM> from shifting.

Moreover, the hot water generator <NUM> according to the present embodiment includes: the pair of anti-rolling stoppers <NUM> that prevents the expansion tank <NUM> from rolling against the rear plate <NUM>; and the tank fixing band <NUM> that has the folded part 66f to be inserted into the band fixing hole <NUM> of the rear plate <NUM> and the flange <NUM> to be fixed to the band fastening hole <NUM> of the rear plate <NUM> by the fastening member <NUM>. Thus, the hot water generator <NUM> can readily and firmly fix the expansion tank <NUM> to the rear plate <NUM>.

Claim 1:
A hot water generator (<NUM>) comprising:
an outdoor unit (<NUM>) that includes therein a compressor (<NUM>) and a heat exchanger (<NUM>), the heat exchanger (<NUM>) being configured to exchange heat between a refrigerant and air; and
a hydro unit (<NUM>) including
a water heat exchanger (<NUM>) that exchanges heat between water and the refrigerant flowing in from the outdoor unit,
a rectangular housing (<NUM>) that has a front face (51f), a rear face(51r), a top face (51t), a bottom face (51b), and a pair of side faces (<NUM>), and
an expansion tank (<NUM>) that has a cylindrical shape, the expansion tank (<NUM>) having a length dimension in a centerline direction larger than diameter dimension, and being accommodated in the housing (<NUM>) with the centerline directed toward the pair of side faces (<NUM>), characterized in that
the expansion tank (<NUM>) includes a cylindrical body (31a), and a convex part (<NUM>) that protrudes outward in a radial direction of the cylindrical body (31a) and extends in a circumferential direction of the cylindrical body (31a), and in that
the hot water generator (<NUM>) further comprises a fixing band (<NUM>) that has a hole (<NUM>) configured to be interdigitated with the convex part (<NUM>), and fixes the expansion tank (<NUM>) to a rear plate (<NUM>) that forms the rear face (51r) of the housing (<NUM>), in a manner that the fixing band (<NUM>) extends on the cylindrical body (31a) from above to below the cylindrical body (31a).