Liquid delivery device and fluid chromatograph

Abstract

A liquid delivery device includes a pump head having a pump chamber provided in the inside, a plunger whose tip is slidably inserted into the pump chamber, and at least one plunger pump having a drive mechanism that reciprocates the plunger in its axial direction. Then, at least one of the plunger pumps is a pressurizing pump that pressurizes a mobile phase including a compressible fluid sucked into the pump chamber and then discharges the mobile phase from the pump chamber, and at least the pump head of the pressurizing pump includes a cooling part that is connected to an outlet channel from the pump chamber, and allows the pump head to absorb heat of the mobile phase discharged from the pump chamber to cool the mobile phase.

Claims

1. A liquid delivery device comprising: at least one or more plunger pumps, wherein the at least one or more plunger pumps each include a pump head having a pump chamber provided in an inside, a plunger having a tip which is slidably inserted into the pump chamber, and a drive mechanism that reciprocates the plunger in an axial direction thereof, at least one of the at least one or more plunger pumps is a pressurizing pump that pressurizes a mobile phase including a compressible fluid sucked into the pump chamber and then discharges the mobile phase from the pump chamber, and at least the pump head of the pressurizing pump includes a cooling part formed by at least one channel connected with an outlet channel of the pump chamber, the cooling part is configured to cause the pump head to absorb heat of a mobile phase that is discharged from the pump chamber and flows into the at least one channel, and is provided to cool the mobile phase.

2. The liquid delivery device according to claim 1, wherein the at least one channel forming the cooling part is a flat plate-shaped channel in which a ratio of an internal surface area to internal capacity is larger than that of the outlet channel.

3. The liquid delivery device according to claim 1, wherein the at least one channel forming the cooling part is a plurality of channels having a smaller cross-sectional area than the outlet channel.

4. The liquid delivery device according to claim 1, wherein the at least one channel forming the cooling part is a plurality of channels having a smaller cross-sectional area than the outlet channel and meander.

5. The liquid delivery device according to claim 2, wherein one wall surface of the at least one channel forming the cooling part is configured to generate an elastic strain in accordance with pressure in the at least one channel, the liquid delivery device further comprising: a strain detection part that detects an amount of strain of the wall surface; and a pressure detection part that detects pressure in the cooling part based on an amount of strain of the wall surface detected by the strain detection part.

6. The liquid delivery device according to claim 1, further comprising a temperature detection part that detects a temperature of the cooling part.

7. The liquid delivery device according to claim 5, further comprising a calorific value calculation part that calculates a calorific value of a mobile phase in the pump chamber based on a change amount of a pressure value detected by the pressure detection part.

8. The liquid delivery device according to claim 6, further comprising a calorific value calculation part that calculates a calorific value of a mobile phase in the pump chamber based on a change amount of a temperature detected by the temperature detection part.

9. The liquid delivery device according to claim 1 comprising an outlet pipe disposed outside the pump head of the pressurizing pump and communicating with the outlet channel, the outlet pipe is covered with a heat insulating member.

10. A fluid chromatograph at least comprising: an analysis channel; a liquid delivery device that includes at least one or more plunger pumps, wherein the at least one or more plunger pumps each include a pump head having a pump chamber provided in an inside, a plunger having a tip which is slidably inserted into the pump chamber, and a drive mechanism that reciprocates the plunger in an axial direction thereof, at least one of the at least one or more plunger pumps is a pressurizing pump that pressurizes a mobile phase including a compressible fluid sucked into the pump chamber and then discharges the mobile phase from the pump chamber, and at least the pump head of the pressurizing pump includes a cooling part formed by at least one channel connected with an outlet channel of the pump chamber, the cooling part is configured to cause the pump head to absorb heat of a mobile phase that is discharged from the pump chamber and flows into the at least one channel, and is provided to cool the mobile phase; the liquid delivery device that delivers a mobile phase in an analysis channel; a sample injection part that injects a sample into the analysis channel; a separation column that is provided downstream of the sample injection part on the analysis channel, and separates a sample injected into the analysis channel by the sample injection part into components; and a detector that is provided downstream of the separation column on the analysis channel and detects the components separated by the separation column.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a schematic cross-sectional view showing an embodiment of a liquid delivery device.

(2) FIG. 2 is a perspective view showing an example of a structure of a cooling part of the embodiment.

(3) FIG. 3 is a graph for explaining operation of each plunger pump of the embodiment.

(4) FIG. 4 is a diagram showing an example in which a primary side outlet pipe of the embodiment has a heat insulating structure.

(5) FIG. 5A is a plan view showing another structural example of the cooling part.

(6) FIG. 5B is a plan view showing still another structural example of the cooling part.

(7) FIG. 6 is a schematic cross-sectional view showing another embodiment of the liquid delivery device.

(8) FIG. 7 is a schematic cross-sectional view showing still another embodiment of the liquid delivery device.

(9) FIG. 8 is a schematic block diagram of a channel showing an embodiment of a fluid chromatograph.

DETAILED DESCRIPTION

(10) Hereinafter, a liquid delivery device and a fluid chromatograph according to the present invention will be described with reference to the drawings.

(11) First, one embodiment of the liquid delivery device will be described with reference to FIG. 1.

(12) A liquid delivery device 1 of this embodiment is a liquid delivery device in a series double plunger system in which a plunger pump 2a (hereinafter, the primary side plunger pump 2a) and a plunger pump 2b (hereinafter, the secondary side plunger pump 2b) are connected in series with each other. In pump heads 4a and 4b of the primary side plunger pump 2a and the secondary side plunger pump 2b, pump chambers 6a and 6b, inlet channels 8a and 8b, and outlet channels 10a and 10b are provided, respectively.

(13) A tip of a plunger 12a is slidably inserted in the pump chamber 6a of the primary side plunger pump 2a. The plunger 12a is reciprocated in an axial direction by a drive mechanism 14a. A tip of a plunger 12b is slidably inserted in the pump chamber 6b of the primary side plunger pump 2b. The plunger 12b is reciprocated in an axial direction by a drive mechanism 14b. The drive mechanisms 14a and 14b include, for example, a cam mechanism and a motor for driving the cam mechanism, and a ball screw mechanism and a motor for driving the ball screw mechanism.

(14) The inlet channel 8a of the primary side plunger pump 2a has one end communicating with the pump chamber 6a, and the other end connected to an inlet pipe 18 via a check valve 16a. The check valve 16a is provided to be opened in response to pressure reduction in the pump chamber 6a when the plunger 12a is driven in a suction direction (a direction to be pulled out from the pump chamber 6a), and to be closed in response to pressurization in the pump chamber 6a when the plunger 12a is driven in a discharge direction (a direction to be pushed into the pump chamber 6a).

(15) A cooling block 20 made from a heat conductive material, such as metal, is attached to the pump head 4a of the primary side plunger pump 2a. In the cooling block 20, a cooling part 22, an inflow channel 24, and an outflow channel 26 are provided. One end of the inflow channel 24 leads to the cooling part 22, and the other end of the inflow channel 24 is connected to the outlet channel 10a leading to a tip of the pump chamber 6a via a joint 28. In this manner, the pump chamber 6a and the cooling part 22 communicate with each other via the outlet channel 10a, the joint 28, and the inflow channel 24. One end of the outflow channel 26 communicates with the cooling part 22, and the other end of the outflow channel 26 is connected to a primary side outlet pipe 30.

(16) The inlet channel 8b of the secondary side plunger pump 2b has one end communicating with the pump chamber 6b, and the other end connected to the other end of the primary side outlet pipe 30 via a check valve 16b. The check valve 16b is provided to be opened when pressure in the pump chamber 6a is higher than pressure in the pump chamber 6b, and to be closed when the pressure in the pump chamber 6a is lower than the pressure in the pump chamber 6b. One end of the outlet channel 10b communicates with a tip of the pump chamber 6b, and the other end of the outlet channel 10b is connected to a secondary side outlet pipe 38.

(17) Since the liquid delivery device 1 is a liquid delivery device of a series type, as shown in FIG. 3, while the primary side plunger pump 2a performs discharge operation, the secondary side plunger pump 2b performs suction operation at a flow rate smaller than a discharge flow rate of the primary side plunger pump 2a, and the secondary side plunger pump 2b sucks part of the mobile phase discharged from the primary side plunger pump 2a. Therefore, while the primary side plunger pump 2a performs the discharge operation, the mobile phase is delivered at a flow rate obtained by subtracting a suction flow rate of the secondary side plunger pump 2b from a discharge flow rate of the primary side plunger pump 2a through the secondary side outlet pipe 38.

(18) On the other hand, while the secondary side plunger pump 2b performs the discharge operation, the primary side plunger pump 2a performs the suction operation and the pre-compression operation. The “pre-compression operation” is operation to increase pressure in the pump chamber 6a after the suction operation of the primary side plunger pump 2a is completed to the same degree as pressure in the pump chamber 6b of the secondary side plunger pump 2b, that is, the system pressure. During the pre-compression operation, the mobile phase in the pump chamber 6a is compressed to generate heat, and the pressure in the pump chamber 6a rises. That is, in this embodiment, the primary side plunger pump corresponds to a “pressurizing pump” that pressurizes and then discharges a mobile phase.

(19) Here, according to heat transfer engineering, when a fluid flowing in a channel has a temperature difference with a channel wall surface (which is assumed to be isothermal) at an inlet of the channel, the temperature difference is known to be attenuated exponentially with respect to a channel length from the inlet. A characteristic length at which the temperature difference becomes 1/e=37% of the inlet depends on a flow rate, thermal diffusivity of the fluid, and the cross-sectional shape of the channel.

(20) The characteristic length required to cool the mobile phase that generates heat in the pump chamber 6a of the primary side plunger pump 2a will calculated. Assume that a discharge flow rate of the primary side plunger pump 2a is 2 mL/min. The thermal diffusivity of the mobile phase is slightly different between water and an organic solvent, but is typically within the range of 1.0×10.sup.−7 to 1.5×10.sup.−7 m.sup.2/s. The characteristic length required to cool the mobile phase that is calculated by using the above numerical values is about 20 to 30 mm. Note that, the cross-sectional shape of the channel is assumed to be a circular pipe. It is known that this model length does not depend on an inner diameter of the circular pipe. This result means that 37% of generated heat still remains even if the mobile phase that generates heat passes through a channel of about 30 mm in length.

(21) Since a diameter of a pump head of a typical plunger pump is 30 to 50 mm, in a case where an outlet channel is provided vertically from a pump chamber of the pump head, the length of the outlet channel is about 15 to 25 mm. This is similar to or shorter than the characteristic length calculated above and is not sufficient to cool the heated mobile phase. For this reason, in the prior art, the mobile phase in a state where heat generated at the time of the pre-compression operation remains is sucked into the pump chamber of the secondary side plunger pump through the primary side outlet pipe. This complicates and makes it difficult to understand the cooling process, and the effectiveness of the feedforward control of the primary side plunger pump taking into consideration thermal expansion and contraction of the mobile phase is impaired.

(22) Referring back to FIG. 1, the cooling part 22 is provided to cause the pump head 4a to absorb the heat of the mobile phase generated during the pre-compression operation described above. For this reason, the cooling block 20 is thermally integrated with the pump head 4a, and heat absorbed by the cooling block 22 from the mobile phase in the cooling part 22 is released to the pump head 4a. In this manner, the mobile phase which is discharged from the pump chamber 6a and flows into the cooling part 22 is cooled to a temperature at the same level as that of the pump head 4a. Here, being thermally integrated means that, for example, the cooling block 20 and the pump head 4a are in a state of being mechanically fastened under a sufficient contact area as shown in FIG. 1.

(23) FIG. 2 shows an example of a structure of the cooling part 22. The cooling part 22 in this example is a flat plate-shaped channel in which a ratio of an internal surface area to internal capacity is larger than that of the outlet channel 10a. As the ratio of the internal surface area to the internal capacity (internal surface area/internal capacity) is larger, the efficiency with which the cooling block 20 absorbs heat from the mobile phase flowing inside the cooling part 22 is more improved. Such a flat plate-shaped channel may have a circular or oval planar shape. A minimum width r in that case is 10 mm or less, more preferably 5 mm or less. Further, a channel depth h is 1 mm or less, more preferably 0.5 mm or less. A ratio of a minimum width to the depth is preferably 2 or more, more preferably 5 or more, and further preferably 10 or more. Internal capacity of the channel having a flat plate shape is preferably 20 uL or less, more preferably 10 uL or less, and further preferably 5 uL or less.

(24) Note that the structure of the cooling part 22 is not limited to the example shown in FIG. 2. The cooling part 22 may be provided with a plurality of parallel channels between the inflow channel 24 and the outflow channel 26 as shown in FIG. 5A, or may be one meandering channel connecting the inflow channel 24 and the outflow channel 26 as shown in FIG. 5B. In a case where the cooling part 22 has the structure shown in FIG. 5A or 5B, the heat quantity of the mobile phase at a typical flow rate of 2 mL/min can be reduced to 37% if the total channel length is 30 mm or more, to (37%).sup.2=14% if the total channel length is 60 mm or more, and to (37%).sup.3=5% if the total channel length is 90 mm or more. If the total channel length is 120 mm or more, the heat quantity can be reduced to (37%).sup.4=2%. The channel depth and the channel width, which do not affect the characteristic length required for cooling, can be typically designed in the range of 0.05 mm to 0.5 mm, and more preferably designed in the range of 0.1 mm to 0.3 mm. The channel depth and the channel width are preferably selected according to the requirements of processing accuracy and internal capacity. The internal capacity is preferably 20 uL or less, more preferably 10 uL or less, and further preferably 5 uL or less.

(25) The structure of the cooling part 22 shown in FIG. 2, FIG. 5A, and FIG. 5B can be manufactured by processing a channel by removal processing, such as machining, etching, sand blast, and electrical discharge machining, and sealing by diffusion bonding, welding, or simply using packing or a gasket.

(26) The mobile phase discharged from the pump chamber 6a is cooled to a temperature similar to that of the pump head 4a in the cooling part 22 and then flows through the primary side outlet pipe 30, and is introduced into the pump head 4b of the secondary side plunger pump 2b. Since the heat capacity of the primary side outlet pipe 30 is smaller than that of the pump head 4a, the primary side outlet pipe 30 is more susceptible to fluctuations in ambient temperature than the pump head 4a, and a temperature of the primary side outlet piping 30 may be different from a temperature of the pump head 4a. In this case, the temperature of the mobile phase cooled to the same level as that of the pump head 4a changes while the mobile phase flows through the primary side outlet pipe 30, which affects the reproducibility of the cooling process of the mobile phase.

(27) In the embodiment of FIG. 4, the stability of a temperature of the primary side outlet pipe 30 is improved by covering the primary side outlet pipe 30 with a heat insulating member 46. Examples of the heat insulating member 46 that covers the primary side outlet pipe 30 include a resin coating, a foamed member, and the like. Note that, in order to obtain an effect similar to that of the heat insulating member 46, the primary side outlet pipe 30 may be accommodated in space thermally isolated from the surroundings by a heat insulating material, or the entire part including the primary side outlet pipe 30 and the primary side pump head 4a of the primary side plunger pump 2a and the pump head 4b of the secondary side plunger pump 2b may be accommodated in such space.

(28) Returning to FIG. 1 and continuing the description, one wall surface 32 of the cooling block 20 that defines the cooling part 22 is configured to be elastically deformed according to the pressure in the cooling part 22. A strain sensor 34 (strain detection part) that detects an amount of strain of the wall surface 32 is attached to the wall surface 32 of the cooling block 20, and a signal of the strain sensor 34 is input to a control part 40 that controls operation of the drive mechanisms 14a and 14b. The control part 40 is implemented by a dedicated computer of the liquid delivery device 1 or a general-purpose personal computer.

(29) The control part 40 includes a pressure detection part 42 that is configured to obtain a pressure value in the cooling part 22 based on the signal value from the strain sensor 34, and a calorific value calculation part 44 configured to calculate a calorific value of the mobile phase in the pump chamber 6a based on a change amount in the pressure value. The control part 40 is provided with data indicating a relationship between the signal value from the strain sensor 34 and the pressure value in the cooling part 22, and the pressure detection part 42 is configured to determine the pressure value in the cooling part 22 based on the data.

(30) A pressure value in the cooling part 22 obtained by a pressure detection part 42 is used for the pre-compression operation of the primary side plunger pump 2a. The control part 40 is configured to control the drive mechanism 14a, so that the pressure in the cooling part 22 obtained by the pressure detection part 42 has a value similar to that of the pressure (system pressure) in the pump chamber 6b of the secondary side plunger pump 2b when the primary side plunger pump 2a performs pre-compression operation. The control part 40 receives a detection signal from a pressure sensor (not shown) that detects the system pressure.

(31) Further, a temperature sensor 36 that detects a temperature of the cooling part 22 is attached to the cooling block 20, and an output signal of the temperature sensor 36 is also input to the control part 40. Note that although the temperature sensor 36 is not an essential constituent, a temperature of the mobile phase in the pump chamber 6a can be monitored by providing the temperature sensor 36. If a change amount in temperature of the mobile phase in the pump chamber 6a at the time of pre-compression operation of the primary side plunger pump 2a is obtained, a calorific value of the mobile phase in the pump chamber 6a at the time of pre-compression can be determined. Therefore, in a case where the temperature sensor 36 is provided, the calorific value calculation part 44 may be configured to obtain the calorific value of the mobile phase based on a change amount in an output signal from the temperature sensor 36 without using the pressure value obtained by the pressure detection part 42.

(32) Further, both the strain sensor and the temperature sensor described above may be provided. At this time, each of the sensors can be used to calculate the calorific value of the mobile phase as described above. Furthermore, the temperature sensor can also be used to correct temperature characteristics of the strain sensor. In this manner, even in a case where the temperature of the strain sensor changes due to heat generation of the mobile phase, the output of the strain sensor can be corrected using the temperature detected by the temperature sensor, and an accurate pressure can be measured.

(33) The calorific value of the mobile phase in the pump chamber 6a obtained by the calorific value calculation part 44 can be used to control the driving speed of the plunger 12a at the time of the discharge operation of the primary side plunger pump 2a. That is, if the calorific value of the mobile phase in the pump chamber 6a is known, it is possible to obtain the size of a loss amount of the liquid delivery flow rate caused by the thermal expansion of the mobile phase due to the heat generation and the subsequent thermal contraction due to cooling in the cooling part 22. Accordingly, by driving the plunger 12a so as to guarantee the loss amount, the stability of the liquid delivery flow rate can be maintained.

(34) Note that the liquid delivery device according to the present invention is not limited to one having the configuration of the embodiment described above.

(35) Hereinafter, another embodiment of the liquid delivery device will be described using FIGS. 6 and 7.

(36) A liquid delivery device 100 of the embodiment of FIG. 6 is a liquid delivery device of a series double plunger type, as similar to the liquid delivery device 1 of FIG. 1. A primary side plunger pump 102a and a secondary side plunger pump 102b are connected in series to each other, and perform the operation shown in FIG. 3 like the liquid delivery device 1. That is, the primary side plunger pump 102a performs suction operation and pre-compression operation during discharge operation of the secondary side plunger pump 102b, and corresponds to the “pressurizing pump” that pressurizes and then discharges the mobile phase in a pump chamber 106a.

(37) The pump chamber 106a and a suction and discharge channel 108a are provided in a pump head 104a of the primary side plunger pump 102a. The suction and discharge channel 108a has one end communicating with a tip of the pump chamber 106a and is provided to extend from the tip of the pump chamber 106a in an axial direction of a plunger 112a.

(38) In this embodiment, a cooling block 120 is mounted on a tip of the pump head 104a of the primary side plunger pump 102a. The cooling block 120 is equivalent to the cooling block 20 in the liquid delivery device 1 of FIG. 1 and includes a cooling part 122, an inflow channel 124, and an outflow channel 126 in the inside. The other end of the suction and discharge channel 108a communicates with the cooling part 122 via the inflow channel 124, and the cooling part 122 further communicates with an inlet channel 150 via the outflow channel 126.

(39) The inlet channel 150 is a channel provided in an inlet block 148 provided on the cooling block 120 on the opposite side to the pump head 104a. One end of the inlet channel 150 is connected to an inlet pipe 118 via a check valve 116a, and the other end of the inlet channel 150 is connected to a primary side outlet pipe 130 via a check valve 116b. The check valve 116a is opened when the plunger 112a is driven in a suction direction by a drive mechanism 114a, and is closed when the plunger 112a is driven in a discharge direction. On the other hand, the check valve 116b is closed when the pressure in a pump chamber 106b is higher than the pressure in the pump chamber 106a, and is opened when the pressure in the pump chamber 106a is higher than the pressure in the pump chamber 106b.

(40) Note that, in this embodiment, the primary side outlet pipe 130 is covered with the heat insulating member 146. However, the heat insulating member 146 is not an essential component.

(41) In the liquid delivery device 100, the mobile phase flows through the cooling part 122 in either the suction operation or the discharge operation of the primary side plunger pump 102a. In this manner, the temperature of the mobile phase sucked into the pump chamber 106a of the primary side plunger pump 102a can be made similar to that of the pump head 104a, and, even in an environment where the temperature of the sucked mobile phase fluctuates due to a room temperature fluctuation, the temperature of the delivered mobile phase can be stabilized more, and the stability of the liquid delivery flow rate can be further improved.

(42) The configuration of the secondary side plunger pump 102b of the liquid delivery device 100 is similar to that of the secondary side plunger pump 2b of the liquid delivery device 1 of FIG. 1, and the pump heads 4b and 104b, the pump chambers 6b and 106b, the inlet channel 8b and 108b, the outlet channels 10b and 110b, the plungers 12b and 112b, the drive mechanisms 14b and 114b, and the outlet channels 38b and 138b correspond to each other.

(43) Like the wall surface 32 of the cooling block 20 of the liquid delivery device 1 of FIG. 1, one wall surface 132 of the cooling block 120 of the liquid delivery device 100 is configured to be elastically deformed in accordance with the pressure in the cooling part 122. Then, a strain sensor 134 that detects an amount of strain of the wall surface 132 is attached to the cooling block 120, and the pressure in the cooling part 122 can be detected based on the amount of strain of the wall surface 132. Note that the configuration of the wall surface 132 and the strain sensor 134 are not essential constituents.

(44) A liquid delivery device 200 of the embodiment of FIG. 7 is a liquid delivery device of a parallel type double plunger type in which two plunger pumps 202a and 202b are connected in parallel. The plunger pumps 202a and 202b alternately perform suction operation and discharge operation, and while one plunger pump is performing the discharge operation, the other plunger pump performs the suction operation and pre-compression operation. That is, in this liquid delivery device 200 of a parallel type, both the plunger pumps 202a and 202b correspond to the “pressurizing pump” which discharges after pressurizing the mobile phase in pump chamber 206a, 206b.

(45) Since both of the plunger pumps 202a and 202b correspond to the “pressurizing pumps”, cooling blocks 220a and 220b are attached to both of these plunger pumps 202a and 202b. The cooling blocks 220a and 220b are equivalent to the cooling block 20 in the liquid delivery device 1 of FIG. 1, and include cooling parts 222a and 222b for cooling the mobile phase discharged from the pump chambers 206a and 206b of the plunger pumps 202a and 202b in the inside.

(46) In a pump head 204a of the plunger pump 202a, the pump chamber 206a, an inlet channel 208a, an outlet channel 210a, and an post-cooling outlet channel 211a are provided. A tip of a plunger 212a is slidably accommodated in the pump chamber 206a, and is configured to reciprocate in an axial direction by a drive mechanism 214a.

(47) The inlet channel 208a has one end communicating with the pump chamber 206a, and the other end connected to an inlet pipe 218 via a check valve 216a. The inlet pipe 218 is also connected to an inlet channel 208b of the plunger pump 202b via a check valve 216b.

(48) The outlet channel 210a has one end communicating with a tip of the pump chamber 206a and the other end connected to an inlet channel 224a communicating with the cooling part 222a via a joint. The post-cooling outlet channel 211a has one end connected to an outlet channel 226a of the cooling block 220a via a joint, and the other end connected to an outlet pipe 238 via a check valve 217a. The outlet pipe 238 is also connected to a post-cooling outlet pipe 211b of the plunger pump 202b via a check valve 217.

(49) As in the wall surface 32 of the cooling block 20 of the liquid delivery device 1 of FIG. 1, one wall surface 232a of the cooling block 220a is configured to be elastically deformed in accordance with the pressure in the cooling part 222a. Then, a strain sensor 234a that detects an amount of strain of the wall surface 232a is attached to the cooling block 220a, and the pressure in the cooling part 222a can be detected based on the amount of strain of the wall surface 232a. Note that the wall surface 232a and the strain sensor 234a are not essential constituents.

(50) The plunger pumps 202b has the same configuration as the plunger pump 202a, and parts corresponding to constituents of the plunger pump 202a are assigned the same numbers, where only signed attached after those numbers are different between “a” and “b”.

(51) As in the above-described embodiment, in the liquid delivery device 200 of a parallel type double plunger type, by providing the cooling parts 222a and 222b for the pump heads 204a and 204b of the plunger pumps 202a and 202b respectively, the mobile phase that has generated heat at the time of pre-compression operation can be cooled to a temperature similar to that of the pump heads 204a and 204b before being delivered. In this manner, the reproducibility of the cooling process of the mobile phase sucked by each plunger pumps 202a and 202b is improved.

(52) Note that, although not particularly shown in FIG. 7, for a pipe provided outside the pump heads 204a and 204b, such as the outlet pipe 238, through which the mobile phase discharged from the plunger pumps 202a and 202b flows, measures may be taken to prevent the influence of a temperature fluctuation in the surrounding environment, in such a manner as covering with a heat insulating member, as in the case of the outlet pipe 38 in FIG. 4.

(53) FIG. 8 is a channel configuration diagram of a liquid chromatograph which is one embodiment of a fluid chromatograph including the liquid delivery device 1, 100, or 200 demonstrated above.

(54) The liquid chromatograph of this embodiment includes an analysis channel 302, the above-described liquid delivery device 1, 100, or 200, a sample injection part 304, a separation column 306, a column oven 308, and a detector 310. The liquid delivery device 1, 100, or 200 is provided to deliver the mobile phase in the analysis channel 302. The sample injection part 304 is an autosampler that automatically injects a sample into the analysis channel 302. The separation column 306 is provided downstream of the sample injection part 304 on the analysis channel 302, and is for separating the sample injected by the sample injection part 304 into components. The separation column 306 is housed in the column oven 308 and has a temperature controlled at a set temperature. The detector 310 is provided downstream of the separation column 306 on the analysis channel 302 and is for detecting a sample component separated in the separation column 306.

(55) In the liquid chromatograph of this embodiment, the liquid delivery device 1, 100, or 200 is configured to deliver a single mobile phase to the sample injection part 304. As another embodiment, different mobile phases delivered by a plurality of liquid delivery devices may be mixed and delivered to the sample injection part 304. Such a configuration is generally known as a “high pressure gradient”. Further, as another different embodiment, a plurality of mobile phases may be mixed and supplied to the liquid delivery device 1, 100, or 200 via a mobile phase switching valve or a proportional valve, and delivered to the sample injection part 304. Such a configuration is generally known as a “low pressure gradient”. The liquid delivery device 1, 100, or 200 disclosed in the present invention can also be applied to liquid chromatographs of various channel configurations other than the embodiment shown in FIG. 8.

(56) Note that, although FIG. 8 shows the liquid chromatograph as an embodiment of a fluid chromatograph, the present invention can be similarly applied to a supercritical fluid chromatograph.